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Tosi M, Fiori L, Tagi VM, Gambino M, Montanari C, Bosetti A, Zuccotti G, Verduci E. Glycomacropeptide-Based Protein Substitutes for Children with Phenylketonuria in Italy: A Nutritional Comparison. Nutrients 2024; 16:956. [PMID: 38612990 PMCID: PMC11013192 DOI: 10.3390/nu16070956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/21/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024] Open
Abstract
Advancements in food science technology have allowed the development of new products for the therapeutic management of inherited metabolic diseases such as phenylketonuria (PKU). Glycomacropeptide (GMP), a peptide derived from casein, is naturally low in phenylalanine (Phe) and, thus, adequate for protein substitutes (PSs) for the management of PKU in children. This review aims primarily to analyse the differences in the nutritional composition of GMP-based protein substitutes in different formulations (ready to drink, powdered, and bars), and secondarily to assess the quality of these products, comparing their nutritional composition with that of standard amino acid (L-AA) mixtures. Thirty-five GMP-based PSs produced by six different companies were included in this review: twenty-one powdered PSs, eight ready to drink, and six bars. The analysis revealed great heterogeneity not only among the different formulations (powdered, ready to drink, and bars) but also within the same group, in terms of energy content and nutritional composition. GMP-based PSs were shown to have higher contents of sugars and saturated fatty acids compared to L-AA PSs, especially in ready-to-drink formulations and bars. The latter also provided the highest amounts of energy among the GMP-based products. This finding may be related to a higher risk of developing overweight and obesity. The greater palatability of these GMP-based PSs, combined with improved nutritional quality, could not only improve adherence to diet therapy but also reduce the incidence of obesity-related comorbidities in PKU.
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Affiliation(s)
- Martina Tosi
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
- Department of Health Sciences, University of Milan, 20146 Milan, Italy
| | - Laura Fiori
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
| | - Veronica Maria Tagi
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
- Department of Biomedical and Clinical Science, University of Milan, 20157 Milan, Italy
| | - Mirko Gambino
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
| | - Chiara Montanari
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
- Department of Biomedical and Clinical Science, University of Milan, 20157 Milan, Italy
| | - Alessandra Bosetti
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
| | - Gianvincenzo Zuccotti
- Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy; (M.T.); (L.F.); (V.M.T.); (M.G.); (C.M.); (A.B.); (G.Z.)
- Department of Biomedical and Clinical Science, University of Milan, 20157 Milan, Italy
| | - Elvira Verduci
- Department of Health Sciences, University of Milan, 20146 Milan, Italy
- Metabolic Diseases Unit, Department of Pediatrics, Vittore Buzzi Children’s Hospital, University of Milan, 20154 Milan, Italy
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2
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Ang T, Mason SA, Dao GM, Bruce CR, Kowalski GM. The impact of a single dose of whey protein on glucose flux and metabolite profiles in normoglycemic males: insights into glucagon and insulin biology. Am J Physiol Endocrinol Metab 2023; 325:E688-E699. [PMID: 37877796 DOI: 10.1152/ajpendo.00182.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/26/2023]
Abstract
Protein ingestion concurrently stimulates euglycemic glucagon and insulin secretion, a response that is particularly robust with rapidly absorbing proteins. Previously, we have shown that ingestion of repeated doses of rapidly absorbing whey protein equally stimulated endogenous glucose production (EGP) and glucose disposal (Rd), thus explaining the preservation of euglycemia. Here, we aimed to determine if a smaller single dose of whey could elicit a large enough glucagon and insulin response to stimulate glucose flux. Therefore, in normoglycemic young adult males (n = 10; age ∼26; BMI ∼25), using [6,6-2H2] glucose tracing and quantitative targeted metabolite profiling, we determined the metabolic response to a single 25 g "standard" dose of whey protein. Whey protein ingestion did not alter glycemia, but increased circulating glucagon (peak 4-fold basal), insulin (peak 6-fold basal), amino acids, and urea while also reducing free fatty acid (FFA) and glycerol concentrations. Interestingly, the postprandial insulin response was driven by both a stimulation of insulin secretion and marked reduction in hepatic insulin clearance. Whey protein ingestion resulted in a modest stimulation of EGP and Rd, both peaking at ∼20% above baseline 1 h after protein ingestion. These findings demonstrate that the ingestion of a single standard serving of whey protein can induce a euglycemic glucagon and insulin response that stimulates glucose flux. We speculate on a theory that could potentially explain how glucagon and insulin synergistically provide hardwired control of nitrogen and glucose homeostasis.NEW & NOTEWORTHY Protein ingestion concurrently stimulates glucagon and insulin secretion. Here we show that in normoglycemic males, ingestion of a single "standard" 25 g serving of rapidly absorbing whey protein drives a sufficiently large glucagon and insulin response, such that it simultaneously increases endogenous glucose production and glucose disposal. We speculate on a novel theory that could potentially explain how the antagonistic/synergistic actions of glucagon and insulin simultaneously provide tight control of glucose and nitrogen homeostasis.
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Affiliation(s)
- Teddy Ang
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
| | - Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
| | - Giang M Dao
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia
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3
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Dassoff E, Shireen A, Wright A. Lipid emulsion structure, digestion behavior, physiology, and health: a scoping review and future directions. Crit Rev Food Sci Nutr 2023:1-33. [PMID: 37947287 DOI: 10.1080/10408398.2023.2273448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Research investigating the effects of the food matrix on health is needed to untangle many unresolved questions in nutritional science. Emulsion structure plays a fundamental role in this inquiry; however, the effects of oil-in-water emulsion structure on broad metabolic, physiological, and health-related outcomes have not been comprehensively reviewed. This systematic scoping review targets this gap and examines methodological considerations for the field of relating food structure and health. MEDLINE, Web of Science, and CAB Direct were searched from inception to December 2022, returning 3106 articles, 52 of which were eligible for inclusion. Many investigated emulsion lipid droplet size and/or gastric colloidal stability and their relation to postprandial weight-loss-related outcomes. The present review also identifies numerous novel relationships between emulsion structures and health-related outcomes. "Omics" endpoints present an exciting avenue for more comprehensive analysis in this area, yet interpretation remains difficult. Identifying valid surrogate biomarkers for long-term outcomes and disease risk will be a turning point for food structure research, leading to breakthroughs in the pace and utility of research that generates advancements in health. The review's findings and recommendations aim to support new hypotheses, future trial design, and evidence-based emulsion design for improved health and well-being.
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Affiliation(s)
- Erik Dassoff
- Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Arshia Shireen
- Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Amanda Wright
- Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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4
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Philbert SA, Xu J, Scholefield M, Patassini S, Church SJ, Unwin RD, Roncaroli F, Cooper GJS. Extensive multiregional urea elevations in a case-control study of vascular dementia point toward a novel shared mechanism of disease amongst the age-related dementias. Front Mol Neurosci 2023; 16:1215637. [PMID: 37520429 PMCID: PMC10372345 DOI: 10.3389/fnmol.2023.1215637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/26/2023] [Indexed: 08/01/2023] Open
Abstract
Introduction Vascular dementia (VaD) is one of the most common causes of dementia among the elderly. Despite this, the molecular basis of VaD remains poorly characterized when compared to other age-related dementias. Pervasive cerebral elevations of urea have recently been reported in several dementias; however, a similar analysis was not yet available for VaD. Methods Here, we utilized ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to measure urea levels from seven brain regions in post-mortem tissue from cases of VaD (n = 10) and controls (n = 8/9). Brain-urea measurements from our previous investigations of several dementias were also used to generate comparisons with VaD. Results Elevated urea levels ranging from 2.2- to 2.4-fold-change in VaD cases were identified in six out of the seven regions analysed, which are similar in magnitude to those observed in uremic encephalopathy. Fold-elevation of urea was highest in the basal ganglia and hippocampus (2.4-fold-change), consistent with the observation that these regions are severely affected in VaD. Discussion Taken together, these data not only describe a multiregional elevation of brain-urea levels in VaD but also imply the existence of a common urea-mediated disease mechanism that is now known to be present in at least four of the main age-related dementias.
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Affiliation(s)
- Sasha A. Philbert
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, School of Medical Sciences, Centre for Advanced Discovery and Experimental Therapeutics, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Jingshu Xu
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, School of Medical Sciences, Centre for Advanced Discovery and Experimental Therapeutics, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Melissa Scholefield
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, School of Medical Sciences, Centre for Advanced Discovery and Experimental Therapeutics, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Stefano Patassini
- Faculty of Science, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Stephanie J. Church
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, School of Medical Sciences, Centre for Advanced Discovery and Experimental Therapeutics, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Richard D. Unwin
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, School of Medical Sciences, Centre for Advanced Discovery and Experimental Therapeutics, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Federico Roncaroli
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, School of Biology, Geoffrey Jefferson Brain Research Centre, The University of Manchester, Manchester, United Kingdom
| | - Garth J. S. Cooper
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, School of Medical Sciences, Centre for Advanced Discovery and Experimental Therapeutics, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
- Faculty of Science, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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5
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Abstract
Diet has a profound impact on the microbial community in the gastrointestinal tract, the intestinal microbiota, to the benefit or detriment of human health. To understand the influence of diet on the intestinal microbiota, research has focused on individual macronutrients. Some macronutrients (e.g. fiber) have been studied in great detail and have been found to strongly influence the intestinal microbiota. The relationship between dietary protein, a vital macronutrient, and the intestinal microbiota has gone largely unexplored. Emerging evidence suggests that dietary protein strongly impacts intestinal microbiota composition and function and that protein-microbiota interactions can have critical impacts on host health. In this review, we focus on recent studies investigating the impact of dietary protein quantity and source on the intestinal microbiota and resulting host health consequences. We highlight major open questions critical to understanding health outcomes mediated by interactions between dietary protein and the microbiota.
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Affiliation(s)
- Alexandria Bartlett
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh NC, USA
- Department of Molecular Genetics and Microbiology, Duke University, Durham NC, USA
- Corresponding author
| | - Manuel Kleiner
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh NC, USA
- Corresponding author
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6
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Glycomacropeptide in PKU-Does It Live Up to Its Potential? Nutrients 2022; 14:nu14040807. [PMID: 35215457 PMCID: PMC8875363 DOI: 10.3390/nu14040807] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/30/2022] [Accepted: 02/07/2022] [Indexed: 02/01/2023] Open
Abstract
The use of casein glycomacropeptide (CGMP) as a protein substitute in phenylketonuria (PKU) has grown in popularity. CGMP is derived from κ casein and is a sialic-rich glycophosphopeptide, formed by the action of chymosin during the production of cheese. It comprises 20–25% of total protein in whey products and has key biomodulatory properties. In PKU, the amino acid sequence of CGMP has been adapted by adding the amino acids histidine, leucine, methionine, tyrosine and tryptophan naturally low in CGMP. The use of CGMP compared to mono amino acids (L-AAs) as a protein substitute in the treatment of PKU promises several potential clinical benefits, although any advantage is supported only by evidence from non-PKU conditions or PKU animal models. This review examines if there is sufficient evidence to support the bioactive properties of CGMP leading to physiological benefits when compared to L-AAs in PKU, with a focus on blood phenylalanine control and stability, body composition, growth, bone density, breath odour and palatability.
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7
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Fotheringham AK, Solon-Biet SM, Bielefeldt-Ohmann H, McCarthy DA, McMahon AC, Ruohonen K, Li I, Sullivan MA, Whiddett RO, Borg DJ, Cogger VC, Ballard WO, Turner N, Melvin RG, Raubenheimer D, Le Couteur DG, Simpson SJ, Forbes JM. Kidney disease risk factors do not explain impacts of low dietary protein on kidney function and structure. iScience 2021; 24:103308. [PMID: 34820603 PMCID: PMC8602032 DOI: 10.1016/j.isci.2021.103308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/29/2021] [Accepted: 10/15/2021] [Indexed: 02/06/2023] Open
Abstract
The kidneys balance many byproducts of the metabolism of dietary components. Previous studies examining dietary effects on kidney health are generally of short duration and manipulate a single macronutrient. Here, kidney function and structure were examined in C57BL/6J mice randomized to consume one of a spectrum of macronutrient combinations (protein [5%–60%], carbohydrate [20%–75%], and fat [20%–75%]) from weaning to late-middle age (15 months). Individual and interactive impacts of macronutrients on kidney health were modeled. Dietary protein had the greatest influence on kidney function, where chronic low protein intake decreased glomerular filtration rates and kidney mass, whereas it increased kidney immune infiltration and structural injury. Kidney outcomes did not align with cardiometabolic risk factors including glucose intolerance, overweight/obesity, dyslipidemia, and hypertension in mice with chronic low protein consumption. This study highlights that protein intake over a lifespan is an important determinant of kidney function independent of cardiometabolic changes. Chronic high macronutrient intake from any source increases kidney function (GFR) Low protein intake led to greater kidney tubular structural injury and inflammation Lower protein intake decreased kidney mass and glomerular filtration capacity Kidney outcomes did not align with longevity or cardiometabolic outcomes
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Affiliation(s)
- Amelia K Fotheringham
- Glycation and Diabetes Complications Group, Mater Research Institute-The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, Brisbane 4072, QLD, Australia.,Faculty of Medicine, University of Queensland, Brisbane 4067, QLD, Australia
| | - Samantha M Solon-Biet
- Charles Perkins Centre, University of Sydney, Sydney 2006, NSW, Australia.,School of Medical Sciences, University of Sydney, Sydney 2006, NSW, Australia
| | - Helle Bielefeldt-Ohmann
- School of Veterinary Science, University of Queensland, Gatton Campus, Gatton 4343, QLD, Australia.,School of Chemistry & Molecular Biosciences, University of Queensland, Brisbane 4067, QLD, Australia
| | - Domenica A McCarthy
- Glycation and Diabetes Complications Group, Mater Research Institute-The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, Brisbane 4072, QLD, Australia
| | - Aisling C McMahon
- Charles Perkins Centre, University of Sydney, Sydney 2006, NSW, Australia.,Centre for Education and Research on Aging, and Aging and Alzheimer's Institute, Concord Hospital, Sydney 2139, NSW, Australia.,ANZAC Research Institute, Concord Hospital, University of Sydney, Sydney 2139, NSW, Australia
| | - Kari Ruohonen
- Animal Nutrition and Health, Cargill, Sandnes, Norway
| | - Isaac Li
- Faculty of Medicine, University of Queensland, Brisbane 4067, QLD, Australia
| | - Mitchell A Sullivan
- Glycation and Diabetes Complications Group, Mater Research Institute-The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, Brisbane 4072, QLD, Australia
| | - Rani O Whiddett
- Glycation and Diabetes Complications Group, Mater Research Institute-The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, Brisbane 4072, QLD, Australia
| | - Danielle J Borg
- Glycation and Diabetes Complications Group, Mater Research Institute-The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, Brisbane 4072, QLD, Australia.,Faculty of Medicine, University of Queensland, Brisbane 4067, QLD, Australia
| | - Victoria C Cogger
- Charles Perkins Centre, University of Sydney, Sydney 2006, NSW, Australia.,Centre for Education and Research on Aging, and Aging and Alzheimer's Institute, Concord Hospital, Sydney 2139, NSW, Australia.,ANZAC Research Institute, Concord Hospital, University of Sydney, Sydney 2139, NSW, Australia
| | - William O Ballard
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, NSW, Australia
| | - Nigel Turner
- Department of Pharmacology, School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, NSW 2052, Australia
| | - Richard G Melvin
- Department of Biomedical Sciences, University of Minnesota Medical School, 1035 University Drive, Duluth 55812, MN, USA
| | - David Raubenheimer
- Charles Perkins Centre, University of Sydney, Sydney 2006, NSW, Australia.,School of Life and Environmental Sciences, University of Sydney, NSW, Australia
| | - David G Le Couteur
- Charles Perkins Centre, University of Sydney, Sydney 2006, NSW, Australia.,Centre for Education and Research on Aging, and Aging and Alzheimer's Institute, Concord Hospital, Sydney 2139, NSW, Australia.,ANZAC Research Institute, Concord Hospital, University of Sydney, Sydney 2139, NSW, Australia
| | - Stephen J Simpson
- Charles Perkins Centre, University of Sydney, Sydney 2006, NSW, Australia.,School of Life and Environmental Sciences, University of Sydney, NSW, Australia
| | - Josephine M Forbes
- Glycation and Diabetes Complications Group, Mater Research Institute-The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, Brisbane 4072, QLD, Australia.,Faculty of Medicine, University of Queensland, Brisbane 4067, QLD, Australia.,Department of Medicine, University of Melbourne, Heidelberg, VIC 3084, Australia
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8
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Sharma A, Tok AIY, Alagappan P, Liedberg B. Point of care testing of sports biomarkers: Potential applications, recent advances and future outlook. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116327] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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9
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Højfeldt G, Bülow J, Agergaard J, Asmar A, Schjerling P, Simonsen L, Bülow J, van Hall G, Holm L. Impact of habituated dietary protein intake on fasting and postprandial whole-body protein turnover and splanchnic amino acid metabolism in elderly men: a randomized, controlled, crossover trial. Am J Clin Nutr 2020; 112:1468-1484. [PMID: 32710741 DOI: 10.1093/ajcn/nqaa201] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 06/29/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Efficacy of protein absorption and subsequent amino acid utilization may be reduced in the elderly. Higher protein intakes have been suggested to counteract this. OBJECTIVES We aimed to elucidate how habituated amounts of protein intake affect the fasted state of, and the stimulatory effect of a protein-rich meal on, protein absorption, whole-body protein turnover, and splanchnic amino acid metabolism. METHODS Twelve men (65-70 y) were included in a double-blinded crossover intervention study, consisting of a 20-d habituation period to a protein intake at the RDA or a high amount [1.1 g · kg lean body mass (LBM)-1 · d-1 or >2.1 g · kg LBM-1 · d-1, respectively], each followed by an experimental trial with a primed, constant infusion of D8-phenylalanine and D2-tyrosine. Arterial and hepatic venous blood samples were obtained after an overnight fast and repeatedly 4 h after a standardized meal including intrinsically labeled whey protein concentrate and calcium-caseinate proteins. Blood was analyzed for amino acid concentrations and phenylalanine and tyrosine tracer enrichments from which whole-body and splanchnic amino acid and protein kinetics were calculated. RESULTS High (compared with the recommended amount of) protein intake resulted in a higher fasting whole-body protein turnover with a resultant mean ± SEM 0.03 ± 0.01 μmol · kg LBM-1 · min-1 lower net balance (P < 0.05), which was not rescued by the intake of a protein-dense meal. The mean ± SEM plasma protein fractional synthesis rate was 0.13 ± 0.06%/h lower (P < 0.05) after habituation to high protein. Furthermore, higher fasting and postprandial amino acid removal were observed after habituation to high protein, yielding higher urea excretion and increased phenylalanine oxidation rates (P < 0.01). CONCLUSIONS Three weeks of habituation to high protein intake (>2.1 g protein · kg LBM-1 · d-1) led to a significantly higher net protein loss in the fasted state. This was not compensated for in the 4-h postprandial period after intake of a meal high in protein.This trial was registered at clinicaltrials.gov as NCT02587156.
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Affiliation(s)
- Grith Højfeldt
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M81, Bispebjerg Hospital, Copenhagen, Denmark
| | - Jacob Bülow
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M81, Bispebjerg Hospital, Copenhagen, Denmark
| | - Jakob Agergaard
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M81, Bispebjerg Hospital, Copenhagen, Denmark
| | - Ali Asmar
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.,Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Peter Schjerling
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M81, Bispebjerg Hospital, Copenhagen, Denmark.,Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lene Simonsen
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
| | - Jens Bülow
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gerrit van Hall
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Clinical Metabolomics Core Facility, Clinical Biochemistry, Rigshospitalet, Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Lars Holm
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M81, Bispebjerg Hospital, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
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10
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Daily Protein and Energy Intake Are Not Associated with Muscle Mass and Physical Function in Healthy Older Individuals-A Cross-Sectional Study. Nutrients 2020; 12:nu12092794. [PMID: 32932629 PMCID: PMC7551652 DOI: 10.3390/nu12092794] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 09/07/2020] [Accepted: 09/10/2020] [Indexed: 02/06/2023] Open
Abstract
Dietary protein has a pivotal role in muscle mass maintenance with advancing age. However, an optimal dose and distribution of protein intake across the day as well as the interaction with energy intake for the maintenance of muscle mass and physical function in healthy older adults remain to be fully elucidated. The purpose of this study was to examine the association between muscle mass, strength, and physical function, and the total amount and distribution of protein and energy intake across the day in healthy older individuals. The research question was addressed in a cross-sectional study including 184 Danish men and woman (age: 70.2 ± 3.9 years, body mass: 74.9 ± 12.1 kg, Body Mass Index (BMI): 25.4 ± 3.7 kg/m2) where a 3-day dietary registration, muscle mass, strength, and functional measurements were collected. We found that neither daily total protein intake nor distribution throughout the day were associated with muscle mass, strength, or physical function. Consequently, we do not provide an incentive for healthy older Danish individuals who already adhere to the current internationally accepted recommended dietary protein intake (0.83 g/kg/day) to change dietary protein intake or its distribution pattern throughout the day.
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11
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Mazzulla M, Abou Sawan S, Williamson E, Hannaian SJ, Volterman KA, West DWD, Moore DR. Protein Intake to Maximize Whole-Body Anabolism during Postexercise Recovery in Resistance-Trained Men with High Habitual Intakes is Severalfold Greater than the Current Recommended Dietary Allowance. J Nutr 2020; 150:505-511. [PMID: 31618421 DOI: 10.1093/jn/nxz249] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/15/2019] [Accepted: 09/13/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Dietary protein supports resistance exercise-induced anabolism primarily via the stimulation of protein synthesis rates. The indicator amino acid oxidation (IAAO) technique provides a noninvasive estimate of the protein intake that maximizes whole-body protein synthesis rates and net protein balance. OBJECTIVE We utilized IAAO to determine the maximal anabolic response to postexercise protein ingestion in resistance-trained men. METHODS Seven resistance-trained men (mean ± SD age 24 ± 3 y; weight 80 ± 9 kg; 11 ± 5% body fat; habitual protein intake 2.3 ± 0.6 g·kg-1·d-1) performed a bout of whole-body resistance exercise prior to ingesting hourly mixed meals, which provided a variable amount of protein (0.20-3.00 g·kg-1·d-1) as crystalline amino acids modeled after egg protein. Steady-state protein kinetics were modeled with oral l-[1-13C]-phenylalanine. Breath and urine samples were taken at isotopic steady state to determine phenylalanine flux (PheRa), phenylalanine excretion (F13CO2; reciprocal of protein synthesis), and net balance (protein synthesis - PheRa). Total amino acid oxidation was estimated from the ratio of urinary urea and creatinine. RESULTS Mixed model biphasic linear regression revealed a plateau in F13CO2 (mean: 2.00; 95% CI: 1.62, 2.38 g protein·kg-1·d-1) (r2 = 0.64; P ˂ 0.01) and in net balance (mean: 2.01; 95% CI: 1.44, 2.57 g protein·kg-1·d-1) (r2 = 0.63; P ˂ 0.01). Ratios of urinary urea and creatinine concentrations increased linearly (r = 0.84; P ˂ 0.01) across the range of protein intakes. CONCLUSIONS A breakpoint protein intake of ∼2.0 g·kg-1·d-1, which maximized whole-body anabolism in resistance-trained men after exercise, is greater than previous IAAO-derived estimates for nonexercising men and is at the upper range of current general protein recommendations for athletes. The capacity to enhance whole-body net balance may be greater than previously suggested to maximize muscle protein synthesis in resistance-trained athletes accustomed to a high habitual protein intake. This trial was registered at clinicaltrials.gov as NCT03696264.
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Affiliation(s)
- Michael Mazzulla
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Sidney Abou Sawan
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Eric Williamson
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Sarkis J Hannaian
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Kimberly A Volterman
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Daniel W D West
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
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Malowany JM, West DWD, Williamson E, Volterman KA, Abou Sawan S, Mazzulla M, Moore DR. Protein to Maximize Whole-Body Anabolism in Resistance-trained Females after Exercise. Med Sci Sports Exerc 2019; 51:798-804. [PMID: 30395050 DOI: 10.1249/mss.0000000000001832] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
INTRODUCTION Current athlete-specific protein recommendations are based almost exclusively on research in males. PURPOSE Using the minimally invasive indicator amino acid oxidation technique, we determined the daily protein intake that maximizes whole-body protein synthesis (PS) and net protein balance (NB) after exercise in strength-trained females. METHODS Eight resistance-trained females (23 ± 3.5 yr, 67.0 ± 7.7 kg, 163.3 ± 3.7 cm, 24.4% ± 6.9% body fat; mean ± SD) completed a 2-d controlled diet during the luteal phase before performing an acute bout of whole-body resistance exercise. During recovery, participants consumed eight hourly meals providing a randomized test protein intake (0.2-2.9 g·kg·d) as crystalline amino acids modeled after egg protein, with constant phenylalanine (30.5 mg·kg·d) and excess tyrosine (40.0 mg·kg·d) intakes. Steady-state whole-body phenylalanine rate of appearance (Ra), oxidation (Ox; the reciprocal of PS), and NB (PS - Ra) were determined from oral [C] phenylalanine ingestion. Total protein oxidation was estimated from the urinary urea-creatinine ratio (U/Cr). RESULTS A mixed model biphase linear regression revealed a break point (i.e., estimated average requirement) of 1.49 ± 0.44 g·kg·d (mean ± 95% confidence interval) in Ox (r = 0.64) and 1.53 ± 0.32 g·kg·d in NB (r = 0.65), indicating a saturation in whole-body anabolism. U/Cr increased linearly with protein intake (r = 0.56, P < 0.01). CONCLUSIONS Findings from this investigation indicate that the safe protein intake (upper 95% confidence interval) to maximize anabolism and minimize protein oxidation for strength-trained females during the early ~8-h postexercise recovery period is at the upper end of the recommendations of the American College of Sports Medicine for athletes (i.e., 1.2-2.0 g·kg·d).
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Affiliation(s)
- Julia M Malowany
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, CANADA
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13
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Mazzulla M, Volterman KA, Packer JE, Wooding DJ, Brooks JC, Kato H, Moore DR. Whole-body net protein balance plateaus in response to increasing protein intakes during post-exercise recovery in adults and adolescents. Nutr Metab (Lond) 2018; 15:62. [PMID: 30258470 PMCID: PMC6154919 DOI: 10.1186/s12986-018-0301-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 09/14/2018] [Indexed: 01/27/2023] Open
Abstract
Background Muscle protein synthesis and muscle net balance plateau after moderate protein ingestion in adults. However, it has been suggested that there is no practical limit to the anabolic response of whole-body net balance to dietary protein. Moreover, limited research has addressed the anabolic response to dietary protein in adolescents. The present study determined whether whole-body net balance plateaued in response to increasing protein intakes during post-exercise recovery and whether there were age- and/or sex-related dimorphisms in the anabolic response. Methods Thirteen adults [7 males (M), 6 females (F)] and 14 adolescents [7 males (AM), 7 females (AF) within ~ 0.4 y from peak height velocity] performed ~ 1 h variable intensity exercise (i.e., Loughborough Intermittent Shuttle Test) prior to ingesting hourly mixed meals that provided a variable amount of protein (0.02-0.25 g·kg- 1·h- 1) as crystalline amino acids modeled after egg protein. Steady-state protein kinetics were modeled noninvasively with oral L-[1-13C]phenylalanine. Breath and urine samples were taken at plateau to determine phenylalanine oxidation and flux (estimate of protein breakdown), respectively. Whole-body net balance was determined by the difference between protein synthesis (flux - oxidation) and protein breakdown. Total amino acid oxidation was estimated from the ratio of urinary urea/creatinine. Results Mixed model biphasic linear regression explained a greater proportion of net balance variance than linear regression (all, r 2 ≥ 0.56; P < 0.01), indicating an anabolic plateau. Net balance was maximized at ~ 0.15, 0.12, 0.12, and 0.11 g protein·kg- 1·h- 1 in M, F, AM, and AF, respectively. When collapsed across age, the y-intercept (net balance at very low protein intake) was greater (overlapping CI did not contain zero) in adolescents vs. adults. Urea/creatinine excretion increased linearly (all, r ≥ 0.76; P < 0.01) across the range of protein intakes. At plateau, net balance was greater (P < 0.05) in AM vs. M. Conclusions Our data suggest there is a practical limit to the anabolic response to protein ingestion within a mixed meal and that higher intakes lead to deamination and oxidation of excess amino acids. Consistent with a need to support lean mass growth, adolescents appear to have greater anabolic sensitivity and a greater capacity to assimilate dietary amino acids than adults.
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Affiliation(s)
- Michael Mazzulla
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON Canada
| | - Kimberly A Volterman
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON Canada
| | - Jeff E Packer
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON Canada
| | - Denise J Wooding
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON Canada
| | - Jahmal C Brooks
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON Canada
| | - Hiroyuki Kato
- 2Frontier Research Laboratories, Institute for Innovation, Ajinomoto Co., Inc, Kawasaki, Japan
| | - Daniel R Moore
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON Canada
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14
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Levitt DG, Levitt MD. A model of blood-ammonia homeostasis based on a quantitative analysis of nitrogen metabolism in the multiple organs involved in the production, catabolism, and excretion of ammonia in humans. Clin Exp Gastroenterol 2018; 11:193-215. [PMID: 29872332 PMCID: PMC5973424 DOI: 10.2147/ceg.s160921] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Increased blood ammonia (NH3) is an important causative factor in hepatic encephalopathy, and clinical treatment of hepatic encephalopathy is focused on lowering NH3. Ammonia is a central element in intraorgan nitrogen (N) transport, and modeling the factors that determine blood-NH3 concentration is complicated by the need to account for a variety of reactions carried out in multiple organs. This review presents a detailed quantitative analysis of the major factors determining blood-NH3 homeostasis – the N metabolism of urea, NH3, and amino acids by the liver, gastrointestinal system, muscle, kidney, and brain – with the ultimate goal of creating a model that allows for prediction of blood-NH3 concentration. Although enormous amounts of NH3 are produced during normal liver amino-acid metabolism, this NH3 is completely captured by the urea cycle and does not contribute to blood NH3. While some systemic NH3 derives from renal and muscle metabolism, the primary site of blood-NH3 production is the gastrointestinal tract, as evidenced by portal vein-NH3 concentrations that are about three times that of systemic blood. Three mechanisms, in order of quantitative importance, release NH3 in the gut: 1) hydrolysis of urea by bacterial urease, 2) bacterial protein deamination, and 3) intestinal mucosal glutamine metabolism. Although the colon is conventionally assumed to be the major site of gut-NH3 production, evidence is reviewed that indicates that the stomach (via Helicobacter pylori metabolism) and small intestine and may be of greater importance. In healthy subjects, most of this gut NH3 is removed by the liver before reaching the systemic circulation. Using a quantitative model, loss of this “first-pass metabolism” due to portal collateral circulation can account for the hyperammonemia observed in chronic liver disease, and there is usually no need to implicate hepatocyte malfunction. In contrast, in acute hepatic necrosis, hyperammonemia results from damaged hepatocytes. Although muscle-NH3 uptake is normally negligible, it can become important in severe hyperammonemia. The NH3-lowering actions of intestinal antibiotics (rifaximin) and lactulose are discussed in detail, with particular emphasis on the seeming lack of importance of the frequently emphasized acidifying action of lactulose in the colon.
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Affiliation(s)
- David G Levitt
- Department of Integrative Biology and Physiology, University of Minnesota
| | - Michael D Levitt
- Research Service, Veterans Affairs Medical Center, Minneapolis, MN, USA
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15
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Lee EC, Fragala MS, Kavouras SA, Queen RM, Pryor JL, Casa DJ. Biomarkers in Sports and Exercise: Tracking Health, Performance, and Recovery in Athletes. J Strength Cond Res 2018; 31:2920-2937. [PMID: 28737585 PMCID: PMC5640004 DOI: 10.1519/jsc.0000000000002122] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lee, EC, Fragala, MS, Kavouras, SA, Queen, RM, Pryor, JL, and Casa, DJ. Biomarkers in sports and exercise: tracking health, performance, and recovery in athletes. J Strength Cond Res 31(10): 2920–2937, 2017—Biomarker discovery and validation is a critical aim of the medical and scientific community. Research into exercise and diet-related biomarkers aims to improve health, performance, and recovery in military personnel, athletes, and lay persons. Exercise physiology research has identified individual biomarkers for assessing health, performance, and recovery during exercise training. However, there are few recommendations for biomarker panels for tracking changes in individuals participating in physical activity and exercise training programs. Our approach was to review the current literature and recommend a collection of validated biomarkers in key categories of health, performance, and recovery that could be used for this purpose. We determined that a comprehensive performance set of biomarkers should include key markers of (a) nutrition and metabolic health, (b) hydration status, (c) muscle status, (d) endurance performance, (e) injury status and risk, and (f) inflammation. Our review will help coaches, clinical sport professionals, researchers, and athletes better understand how to comprehensively monitor physiologic changes, as they design training cycles that elicit maximal improvements in performance while minimizing overtraining and injury risk.
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Affiliation(s)
- Elaine C Lee
- 1Department of Kinesiology, University of Connecticut, Storrs, Connecticut; 2Quest Diagnostics, Madison, New Jersey; 3Department of Health, Human Performance, & Recreation, University of Arkansas, Fayetteville, Arkansas; 4Department of Biomedical Engineering and Mechanics, Virginia Tech University, Blacksburg, Virginia; and 5Department of Kinesiology, California State University, Fresno, California
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16
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Affiliation(s)
| | | | - Malcolm McLeod
- College of Physical and Mathematical Sciences, Australian National University Canberra
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17
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Vu JP, Luong L, Parsons WF, Oh S, Sanford D, Gabalski A, Lighton JRB, Pisegna JR, Germano PM. Long-Term Intake of a High-Protein Diet Affects Body Phenotype, Metabolism, and Plasma Hormones in Mice. J Nutr 2017; 147:2243-2251. [PMID: 29070713 PMCID: PMC5697971 DOI: 10.3945/jn.117.257873] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 07/26/2017] [Accepted: 09/26/2017] [Indexed: 01/08/2023] Open
Abstract
Background: High-protein diets (HPDs) recently have been used to obtain body weight and fat mass loss and expand muscle mass. Several studies have documented that HPDs reduce appetite and food intake.Objective: Our goal was to determine the long-term effects of an HPD on body weight, energy intake and expenditure, and metabolic hormones.Methods: Male C57BL/6 mice (8 wk old) were fed either an HPD (60% of energy as protein) or a control diet (CD; 20% of energy as protein) for 12 wk. Body composition and food intakes were determined, and plasma hormone concentrations were measured in mice after being fed and after overnight feed deprivation at several time points.Results: HPD mice had significantly lower body weight (in means ± SEMs; 25.73 ± 1.49 compared with 32.5 ± 1.31 g; P = 0.003) and fat mass (9.55% ± 1.24% compared with 15.78% ± 2.07%; P = 0.05) during the first 6 wk compared with CD mice, and higher lean mass throughout the study starting at week 2 (85.45% ± 2.25% compared with 75.29% ± 1.90%; P = 0.0001). Energy intake, total energy expenditure, and respiratory quotient were significantly lower in HPD compared with CD mice as shown by cumulative energy intake and eating rate. Water vapor was significantly higher in HPD mice during both dark and light phases. In HPD mice, concentrations of leptin [feed-deprived: 41.31 ± 11.60 compared with 3041 ± 683 pg/mL (P = 0.0004); postprandial: 112.5 ± 102.0 compared with 8273 ± 1415 pg/mL (P < 0.0001)] and glucagon-like peptide 1 (GLP-1) [feed-deprived: 5.664 ± 1.44 compared with 21.31 ± 1.26 pg/mL (P = <0.0001); postprandial: 6.54 ± 2.13 compared with 50.62 ± 11.93 pg/mL (P = 0.0037)] were significantly lower, whereas postprandial glucagon concentrations were higher than in CD-fed mice.Conclusions: In male mice, the 12-wk HPD resulted in short-term body weight and fat mass loss, but throughout the study preserved body lean mass and significantly reduced energy intake and expenditure as well as leptin and GLP-1 concentrations while elevating postprandial glucagon concentrations. This study suggests that long-term use of HPDs may be an effective strategy to decrease energy intake and expenditure and to maintain body lean mass.
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Affiliation(s)
- John P Vu
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | - Leon Luong
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | - William F Parsons
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | - Suwan Oh
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | - Daniel Sanford
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | - Arielle Gabalski
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | | | - Joseph R Pisegna
- CURE–Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA;,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
| | - Patrizia M Germano
- CURE-Digestive Diseases Research Center, Department of Medicine at the University of California at Los Angeles, Los Angeles, CA; .,Division of Gastroenterology, Hepatology, and Parenteral Nutrition, Veterans Affairs (VA) Greater Los Angeles Health Care System and Division of Digestive Diseases, David Geffen School of Medicine, Los Angeles, CA; and
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18
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Lustgarten MS, Fielding RA. Metabolites related to renal function, immune activation, and carbamylation are associated with muscle composition in older adults. Exp Gerontol 2017; 100:1-10. [PMID: 29030163 DOI: 10.1016/j.exger.2017.10.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 09/28/2017] [Accepted: 10/01/2017] [Indexed: 12/25/2022]
Abstract
Reduced skeletal muscle density in older adults is associated with insulin resistance, decreased physical function, and an increased all-cause mortality risk. To elucidate mechanisms that may underlie the maintenance of skeletal muscle density, we conducted a secondary analysis of previously published muscle composition and serum metabolomic data in 73 older adults (average age, 78y). Multivariable-adjusted linear regression was used to examine associations between 321 metabolites with muscle composition, defined as the ratio between normal density (NDM) with low density (LDM) thigh muscle cross sectional area (NDM/LDM). Sixty metabolites were significantly (p≤0.05 and q<0.30) associated with NDM/LDM. Decreased renal function and the immune response have been previously linked with reduced muscle density, but the mechanisms underlying these connections are less clear. Metabolites that were significantly associated with muscle composition were then tested for their association with circulating markers of renal function (blood urea nitrogen, creatinine, uric acid), and with the immune response (neutrophils/lymphocytes) and activation (kynurenine/tryptophan). 43 significant NDM/LDM metabolites (including urea) were co-associated with at least 1 marker of renal function; 23 of these metabolites have been previously identified as uremic solutes. The neutrophil/lymphocyte ratio was significantly associated with NDM/LDM (β±SE: -0.3±0.1, p=0.01, q=0.04). 35 significant NDM/LDM metabolites were co-associated with immune activation. Carbamylation (defined as homocitrulline/lysine) was identified as a pathway that may link renal function and immune activation with muscle composition, as 29 significant NDM/LDM metabolites were co-associated with homocitrulline/lysine, with at least 2 markers of renal function, and with kynurenine/tryptophan. When considering that elevated urea and uremic metabolites have been linked with an increased systemic microbial burden, that antimicrobial defense can be reduced in the presence of carbamylation, and that adipocytes can promote host defense, we propose the novel hypothesis that the age-related increase in adipogenesis within muscle may be a compensatory antimicrobial response to protect against an elevated microbial burden.
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Affiliation(s)
- Michael S Lustgarten
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center, Tufts University, Boston, MA, USA.
| | - Roger A Fielding
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center, Tufts University, Boston, MA, USA
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19
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Tucker MA, Butts CL, Satterfield AZ, Six A, Johnson EC, Ganio MS. Spot Sample Urine Specific Gravity Does Not Accurately Represent Small Decreases in Plasma Volume in Resting Healthy Males. J Am Coll Nutr 2017; 37:17-23. [PMID: 28985131 DOI: 10.1080/07315724.2017.1323692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Urine specific gravity (USG) is often used to assess hydration status, particularly around athletic competition, but it is unknown whether high USG is indicative of plasma volume (PV) reduction (i.e., hypohydration). We tested the hypothesis that if high USG is reflective of reduced PV, subsequent fluid ingestion would increase PV. PURPOSE The purpose of this study was to examine 24-hour changes in USG and PV in individuals presenting with high and low spot USG. METHODS Nineteen healthy males were provided food and water over 24 hours with a total water volume of 35 ml·kg-1 body mass. Absolute PV and blood volume (BV), measured using the CO-rebreathe technique, along with USG were measured before and after a 24-hour intervention period. Based on a preintervention morning spot USG, subjects were post hoc assigned to groups according to USG (≤1.020 or >1.020; low and high USG, respectively). RESULTS Despite presenting with an elevated spot USG (1.026 ± 0.004), subsequent fluid ingestion over 24 hours did not lead to changes (∆) in PV (-75 ± 234 ml) or BV (-156 ± 370 ml) in the high USG group (p > 0.05). However, a spot USG after the 24-hour intervention in this group decreased (p = 0.018) to a level indicating improved hydration status (1.017 ± 0.007). In the low USG group, there were no changes in PV (-39 ± 274 ml), BV (-82 ± 396 ml), or USG (0.003 ± 0.007) over the 24-hour fluid intervention (all p > 0.05). CONCLUSIONS Despite a high preintervention USG and subsequent decrease after 24-hour fluid intake, measures of PV and BV were not indicative of this seemingly improved hydration status. This suggests that a highly concentrated spot sample USG and subsequent changes are not accurately representative of PV or BV.
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Affiliation(s)
- Matthew A Tucker
- a Department of Health , Human Performance, and Recreation, University of Arkansas , Fayetteville , Arkansas , USA.,b Georgia Prevention Institute, Augusta University , Augusta , Georgia , USA
| | - Cory L Butts
- a Department of Health , Human Performance, and Recreation, University of Arkansas , Fayetteville , Arkansas , USA
| | - Alf Z Satterfield
- a Department of Health , Human Performance, and Recreation, University of Arkansas , Fayetteville , Arkansas , USA
| | - Ashley Six
- a Department of Health , Human Performance, and Recreation, University of Arkansas , Fayetteville , Arkansas , USA
| | - Evan C Johnson
- a Department of Health , Human Performance, and Recreation, University of Arkansas , Fayetteville , Arkansas , USA.,c Division of Kinesiology and Health , University of Wyoming , Laramie , Wyoming , USA
| | - Matthew S Ganio
- a Department of Health , Human Performance, and Recreation, University of Arkansas , Fayetteville , Arkansas , USA
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20
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Beaumont M, Portune KJ, Steuer N, Lan A, Cerrudo V, Audebert M, Dumont F, Mancano G, Khodorova N, Andriamihaja M, Airinei G, Tomé D, Benamouzig R, Davila AM, Claus SP, Sanz Y, Blachier F. Quantity and source of dietary protein influence metabolite production by gut microbiota and rectal mucosa gene expression: a randomized, parallel, double-blind trial in overweight humans. Am J Clin Nutr 2017; 106:1005-1019. [PMID: 28903954 DOI: 10.3945/ajcn.117.158816] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 08/01/2017] [Indexed: 12/21/2022] Open
Abstract
Background: Although high-protein diets (HPDs) are frequently consumed for body-weight control, little is known about the consequences for gut microbiota composition and metabolic activity and for large intestine mucosal homeostasis. Moreover, the effects of HPDs according to the source of protein need to be considered in this context.Objective: The objective of this study was to evaluate the effects of the quantity and source of dietary protein on microbiota composition, bacterial metabolite production, and consequences for the large intestinal mucosa in humans.Design: A randomized, double-blind, parallel-design trial was conducted in 38 overweight individuals who received a 3-wk isocaloric supplementation with casein, soy protein, or maltodextrin as a control. Fecal and rectal biopsy-associated microbiota composition was analyzed by 16S ribosomal DNA sequencing. Fecal, urinary, and plasma metabolomes were assessed by 1H-nuclear magnetic resonance. Mucosal transcriptome in rectal biopsies was determined with the use of microarrays.Results: HPDs did not alter the microbiota composition, but induced a shift in bacterial metabolism toward amino acid degradation with different metabolite profiles according to the protein source. Correlation analysis identified new potential bacterial taxa involved in amino acid degradation. Fecal water cytotoxicity was not modified by HPDs, but was associated with a specific microbiota and bacterial metabolite profile. Casein and soy protein HPDs did not induce inflammation, but differentially modified the expression of genes playing key roles in homeostatic processes in rectal mucosa, such as cell cycle or cell death.Conclusions: This human intervention study shows that the quantity and source of dietary proteins act as regulators of gut microbiota metabolite production and host gene expression in the rectal mucosa, raising new questions on the impact of HPDs on the large intestine mucosa homeostasis. This trial was registered at clinicaltrials.gov as NCT02351297.
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Affiliation(s)
- Martin Beaumont
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France
| | - Kevin Joseph Portune
- Microbial Ecology, Nutrition and Health Research Unit, Institute of agronomy and food technology - Spanish National Research Council, Valencia, Spain
| | - Nils Steuer
- Department of Gastroenterology, Avicenne Hospital, Public Assistance-Hospital of Paris, Bobigny, France
| | - Annaïg Lan
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France
| | - Victor Cerrudo
- Microbial Ecology, Nutrition and Health Research Unit, Institute of agronomy and food technology - Spanish National Research Council, Valencia, Spain
| | - Marc Audebert
- Research Centre in Food Toxicology, University of Toulouse, INRA, Toulouse National Veterinary School, Polytechnic National Institute - Purpan, Paul Sabatier University, Toulouse, France
| | | | - Giulia Mancano
- Department of Food and Nutritional Sciences, University of Reading, Reading, United Kingdom
| | - Nadezda Khodorova
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France
| | - Mireille Andriamihaja
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France
| | - Gheorghe Airinei
- Department of Gastroenterology, Avicenne Hospital, Public Assistance-Hospital of Paris, Bobigny, France
| | - Daniel Tomé
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France
| | - Robert Benamouzig
- Department of Gastroenterology, Avicenne Hospital, Public Assistance-Hospital of Paris, Bobigny, France
| | - Anne-Marie Davila
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France
| | - Sandrine Paule Claus
- Department of Food and Nutritional Sciences, University of Reading, Reading, United Kingdom
| | - Yolanda Sanz
- Microbial Ecology, Nutrition and Health Research Unit, Institute of agronomy and food technology - Spanish National Research Council, Valencia, Spain
| | - François Blachier
- Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France;
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Effects of poly-γ-glutamic acid (γ-PGA) on plant growth and its distribution in a controlled plant-soil system. Sci Rep 2017; 7:6090. [PMID: 28729559 PMCID: PMC5519684 DOI: 10.1038/s41598-017-06248-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 06/05/2017] [Indexed: 12/02/2022] Open
Abstract
To demonstrate the responses of plant (Pakchoi) and soil to poly-γ-glutamic acid (γ-PGA) is essential to better understand the pathways of the promotional effect of γ-PGA on plant growth. In this study, the effects of γ-PGA on soil nutrient availability, plant nutrient uptake ability, plant metabolism and its distribution in a plant-soil system were tested using labeled γ-PGA synthesized from 13C1-15N-L-glutamic acid (L-Glu). γ-PGA significantly improved plant uptake of nitrogen (N), phosphorus (P), and potassium (K) and hence increased plant biomass. γ-PGA greatly strengthened the plant nutrient uptake capacity through enhancing both root biomass and activity. γ-PGA affected carbon (C) and N metabolism in plant which was evidenced with increased soluble sugar contents and decreased nitrate and free amino acids contents. About 26.5% of the γ-PGA-N uptake during the first 24 h, after γ-PGA application, was in the form of intact organic molecular. At plant harvest, 29.7% and 59.4% of γ-PGA-15N was recovered in plant and soil, respectively, with a 5.64% of plant N nutrition being derived from γ-PGA-N. The improved plant nutrient uptake capacity and soil nutrient availability by γ-PGA may partly explain the promotional effect of γ-PGA, however, the underlying reason may be closely related to L-Glu.
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Read MN, Holmes AJ. Towards an Integrative Understanding of Diet-Host-Gut Microbiome Interactions. Front Immunol 2017; 8:538. [PMID: 28533782 PMCID: PMC5421151 DOI: 10.3389/fimmu.2017.00538] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/21/2017] [Indexed: 12/11/2022] Open
Abstract
Over the last 20 years, a sizeable body of research has linked the microbiome and host diet to a remarkable diversity of diseases. Yet, unifying principles of microbiome assembly or function, at levels required to rationally manipulate a specific individual's microbiome to their benefit, have not emerged. A key driver of both community composition and activity is the host diet, but diet-microbiome interactions cannot be characterized without consideration of host-diet interactions such as appetite and digestion. This becomes even more complex if health outcomes are to be explored, as microbes engage in multiple interactions and feedback pathways with the host. Here, we review these interactions and set forth the need to build conceptual models of the diet-microbiome-host axes that draw out the key principles governing this system's dynamics. We highlight how "units of response," characterizations of similarly behaving microbes, do not correlate consistently with microbial sequence relatedness, raising a challenge for relating high-throughput data sets to conceptual models. Furthermore, they are question-specific; responses to resource environment may be captured at higher taxonomic levels, but capturing microbial products that depend on networks of different interacting populations, such as short-chain fatty acid production through anaerobic fermentation, can require consideration of the entire community. We posit that integrative approaches to teasing apart diet-microbe-host interactions will help bridge between experimental data sets and conceptual models and will be of value in formulating predictive models.
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Affiliation(s)
- Mark N. Read
- The School of Environmental and Life Sciences, The Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
| | - Andrew J. Holmes
- The School of Environmental and Life Sciences, The Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
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Stepien M, Azzout-Marniche D, Even PC, Khodorova N, Fromentin G, Tomé D, Gaudichon C. Adaptation to a high-protein diet progressively increases the postprandial accumulation of carbon skeletons from dietary amino acids in rats. Am J Physiol Regul Integr Comp Physiol 2016; 311:R771-R778. [PMID: 27581809 DOI: 10.1152/ajpregu.00040.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 07/26/2016] [Indexed: 11/22/2022]
Abstract
We aimed to determine whether oxidative pathways adapt to the overproduction of carbon skeletons resulting from the progressive activation of amino acid (AA) deamination and ureagenesis under a high-protein (HP) diet. Ninety-four male Wistar rats, of which 54 were implanted with a permanent jugular catheter, were fed a normal protein diet for 1 wk and were then switched to an HP diet for 1, 3, 6, or 14 days. On the experimental day, they were given their meal containing a mixture of 20 U-[15N]-[13C] AA, whose metabolic fate was followed for 4 h. Gastric emptying tended to be slower during the first 3 days of adaptation. 15N excretion in urine increased progressively during the first 6 days, reaching 29% of ingested protein. 13CO2 excretion was maximal, as early as the first day, and represented only 16% of the ingested proteins. Consequently, the amount of carbon skeletons remaining in the metabolic pools 4 h after the meal ingestion progressively increased to 42% of the deaminated dietary AA after 6 days of HP diet. In contrast, 13C enrichment of plasma glucose tended to increase from 1 to 14 days of the HP diet. We conclude that there is no oxidative adaptation in the early postprandial period to an excess of carbon skeletons resulting from AA deamination in HP diets. This leads to an increase in the postprandial accumulation of carbon skeletons throughout the adaptation to an HP diet, which can contribute to the sustainable satiating effect of this diet.
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Affiliation(s)
- Magdalena Stepien
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
| | - Dalila Azzout-Marniche
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
| | - Patrick C Even
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
| | - Nadezda Khodorova
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
| | - Gilles Fromentin
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
| | - Daniel Tomé
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
| | - Claire Gaudichon
- UMR Physiologie de la Nutrition du Comportement Alimentaire, AgroParisTech, Institut National de la Recherche Agronomique, Université Paris Saclay, Paris, France
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Abstract
Urea is generated by the urea cycle enzymes, which are mainly in the liver but are also ubiquitously expressed at low levels in other tissues. The metabolic process is altered in several conditions such as by diets, hormones, and diseases. Urea is then eliminated through fluids, especially urine. Blood urea nitrogen (BUN) has been utilized to evaluate renal function for decades. New roles for urea in the urinary system, circulation system, respiratory system, digestive system, nervous system, etc., were reported lately, which suggests clinical significance of urea.
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Abstract
Human adults produce around 1000 mmol of ammonia daily. Some is reutilized in biosynthesis. The remainder is waste and neurotoxic. Eventually most is excreted in urine as urea, together with ammonia used as a buffer. In extrahepatic tissues, ammonia is incorporated into nontoxic glutamine and released into blood. Large amounts are metabolized by the kidneys and small intestine. In the intestine, this yields ammonia, which is sequestered in portal blood and transported to the liver for ureagenesis, and citrulline, which is converted to arginine by the kidneys. The amazing developments in NMR imaging and spectroscopy and molecular biology have confirmed concepts derived from early studies in animals and cell cultures. The processes involved are exquisitely tuned. When they are faulty, ammonia accumulates. Severe acute hyperammonemia causes a rapidly progressive, often fatal, encephalopathy with brain edema. Chronic milder hyperammonemia causes a neuropsychiatric illness. Survivors of severe neonatal hyperammonemia have structural brain damage. Proposed explanations for brain edema are an increase in astrocyte osmolality, generally attributed to glutamine accumulation, and cytotoxic oxidative/nitrosative damage. However, ammonia neurotoxicity is multifactorial, with disturbances also in neurotransmitters, energy production, anaplerosis, cerebral blood flow, potassium, and sodium. Around 90% of hyperammonemic patients have liver disease. Inherited defects are rare. They are being recognized increasingly in adults. Deficiencies of urea cycle enzymes, citrin, and pyruvate carboxylase demonstrate the roles of isolated pathways in ammonia metabolism. Phenylbutyrate is used routinely to treat inherited urea cycle disorders, and its use for hepatic encephalopathy is under investigation.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom.
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26
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Petzke KJ, Freudenberg A, Klaus S. Beyond the role of dietary protein and amino acids in the prevention of diet-induced obesity. Int J Mol Sci 2014; 15:1374-91. [PMID: 24447927 PMCID: PMC3907874 DOI: 10.3390/ijms15011374] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/09/2014] [Accepted: 01/09/2014] [Indexed: 12/22/2022] Open
Abstract
High-protein diets have been shown to prevent the development of diet-induced obesity and can improve associated metabolic disorders in mice. Dietary leucine supplementation can partially mimic this effect. However, the molecular mechanisms triggering these preventive effects remain to be satisfactorily explained. Here we review studies showing a connection between high protein or total amino nitrogen intake and obligatory water intake. High amino nitrogen intake may possibly lower lipid storage, and prevent insulin resistance. Suggestions are made for further systematical studies to explore the relationship between water consumption, satiety, and energy expenditure. Moreover, these examinations should better distinguish between leucine-specific and unspecific effects. Research in this field can provide important information to justify dietary recommendations and strategies in promoting long-term weight loss and may help to reduce health problems associated with the comorbidities of obesity.
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Affiliation(s)
- Klaus J Petzke
- German Institute of Human Nutrition in Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, Nuthetal 14558, Germany.
| | - Anne Freudenberg
- German Institute of Human Nutrition in Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, Nuthetal 14558, Germany.
| | - Susanne Klaus
- German Institute of Human Nutrition in Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, Nuthetal 14558, Germany.
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27
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Martin W, Armstrong L, Rodriguez N. Dietary Protein Intake and Renal Function. Clin Nutr 2013. [DOI: 10.1201/b16308-10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Van Calcar SC, Ney DM. Food products made with glycomacropeptide, a low-phenylalanine whey protein, provide a new alternative to amino Acid-based medical foods for nutrition management of phenylketonuria. J Acad Nutr Diet 2012; 112:1201-10. [PMID: 22818728 PMCID: PMC3402906 DOI: 10.1016/j.jand.2012.05.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 04/10/2012] [Indexed: 02/06/2023]
Abstract
Phenylketonuria (PKU), an inborn error in phenylalanine metabolism, requires lifelong nutrition management with a low-phenylalanine diet, which includes a phenylalanine-free amino acid-based medical formula to provide the majority of an individual's protein needs. Compliance with this diet is often difficult for older children, adolescents, and adults with PKU. The whey protein glycomacropeptide (GMP) is ideally suited for the PKU diet because it is naturally low in phenylalanine. Nutritionally complete, acceptable medical foods and beverages can be made with GMP to increase the variety of protein sources for the PKU diet. As an intact protein, GMP improves protein use and increases satiety compared with amino acids. Thus, GMP provides a new, more physiologic source of low-phenylalanine dietary protein for people with PKU.
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Affiliation(s)
- Sandra C. Van Calcar
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Senior Metabolic Dietitian, Biochemical Genetics Program, Waisman Center, University of Wisconsin-Madison, 1500 Highland Ave., Madison, WI 53705, Phone: 608-263-5981, Fax: 608-263-0530
| | - Denise M. Ney
- Billings Bascom Professor, Department of Nutritional Sciences and Waisman Center, University of Wisconsin-Madison, 1415 Linden Drive, Madison, WI 53703, Phone: 608-262-4386, Fax: 608-262-5860
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Freudenberg A, Petzke KJ, Klaus S. Dietary l-leucine and l-alanine supplementation have similar acute effects in the prevention of high-fat diet-induced obesity. Amino Acids 2012; 44:519-28. [DOI: 10.1007/s00726-012-1363-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/06/2012] [Indexed: 10/28/2022]
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Liu L, Mo H, Wei S, Raftery D. Quantitative analysis of urea in human urine and serum by 1H nuclear magnetic resonance. Analyst 2011; 137:595-600. [PMID: 22179722 DOI: 10.1039/c2an15780b] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A convenient and fast method for quantifying urea in biofluids is demonstrated using NMR analysis and the solvent water signal as a concentration reference. The urea concentration can be accurately determined with errors less than 3% between 1 mM and 50 mM, and less than 2% above 50 mM in urine and serum. The method is promising for various applications with advantages of simplicity, high accuracy, and fast non-destructive detection. With an ability to measure other metabolites simultaneously, this NMR method is also likely to find applications in metabolic profiling and system biology.
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Affiliation(s)
- Lingyan Liu
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Dr, West Lafayette, IN 47907, USA
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Fouillet H, Juillet B, Gaudichon C, Mariotti F, Tomé D, Bos C. Absorption kinetics are a key factor regulating postprandial protein metabolism in response to qualitative and quantitative variations in protein intake. Am J Physiol Regul Integr Comp Physiol 2009; 297:R1691-705. [PMID: 19812354 DOI: 10.1152/ajpregu.00281.2009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that increasing the habitual protein intake widened the gap in nutritional quality between proteins through mechanisms that are not yet fully understood. We hypothesized that the differences in gastrointestinal kinetics between dietary proteins were an important factor affecting their differential response to an increased protein intake. To test this hypothesis, we built a 13-compartment model providing integrative insight into the sequential dynamics of meal nitrogen (Nm) absorption, splanchnic uptake, and metabolism, and subsequent peripheral transfer and deposition. The model was developed from data on postprandial Nm kinetics in certain accessible pools, obtained from subjects having ingested a (15)N-labeled milk or soy protein meal, after adaptation to normal (NP) or high (HP) protein diets. The faster absorption of Nm after soy vs. milk caused its earlier and stronger splanchnic delivery, which favored its local catabolic utilization (up to +30%) and limited its peripheral accretion (down to -20%). Nm absorption was also accelerated after HP vs. NP adaptation, and this kinetic effect accounted for most of the HP-induced increase (up to +20%) in splanchnic Nm catabolic use, and the decrease (down to -25%) in peripheral Nm anabolic utilization. The HP-induced acceleration in Nm absorption was more pronounced with soy than with milk, as were the HP effects on Nm regional metabolism. Our integrative approach identified Nm absorption kinetics, which exert a direct and lasting impact on Nm splanchnic catabolic use and peripheral delivery, as being critical in adaptation to both qualitative and quantitative changes in protein intake.
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Affiliation(s)
- Hélène Fouillet
- INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France.
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Abstract
The urea cycle is the final pathway for removal of surplus nitrogen from the body, and the major route in humans for detoxification of ammonia. The full complement of enzymes is expressed only in liver. Inherited deficiencies of urea cycle enzymes lead to hyperammonaemia, which causes brain damage. Severe defects present with hyperammonaemic crises in neonates. Equally devastating episodes may occur in previously asymptomatic adults with mild defects, most often X-linked ornithine transcarbamylase (OTC) deficiency. Several mechanisms probably contribute to pathogenesis. Treatment aims to reduce plasma ammonia quickly, reduce production of waste nitrogen, dispose of waste nitrogen using alternative pathways to the urea cycle and replace arginine. These therapies have increased survival and probably improve the neurological outcome. Arginine, sodium benzoate, sodium phenylbutyrate and, less often, sodium phenylacetate are used. Long-term correction is achieved by liver transplantation. Gene therapy for OTC deficiency is effective in animals, and work is ongoing to improve persistence and safety.
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Affiliation(s)
- V Walker
- Department of Clinical Biochemistry, Southampton University Hospitals NHS Trust, Southampton General Hospital, Southampton, UK. valerie.walker @suht.swest.nhs.uk
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van Calcar SC, MacLeod EL, Gleason ST, Etzel MR, Clayton MK, Wolff JA, Ney DM. Improved nutritional management of phenylketonuria by using a diet containing glycomacropeptide compared with amino acids. Am J Clin Nutr 2009; 89:1068-77. [PMID: 19244369 PMCID: PMC2667457 DOI: 10.3945/ajcn.2008.27280] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 01/22/2009] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Phenylketonuria (PKU) requires a lifelong low-phenylalanine diet that provides the majority of protein from a phenylalanine-free amino acid (AA) formula. Glycomacropeptide (GMP), an intact protein formed during cheese production, contains minimal phenylalanine. OBJECTIVE The objective was to investigate the effects of substituting GMP food products for the AA formula on acceptability, safety, plasma AA concentrations, and measures of protein utilization in subjects with PKU. DESIGN Eleven subjects participated in an inpatient metabolic study with two 4-d treatments: a current AA diet (AA diet) followed by a diet that replaced the AA formula with GMP (GMP diet) supplemented with limiting AAs. Plasma concentrations of AAs, blood chemistries, and insulin were measured and compared in AA (day 4) and GMP diets (day 8). RESULTS The GMP diet was preferred to the AA diet in 10 of 11 subjects with PKU, and there were no adverse reactions to GMP. There was no significant difference in phenylalanine concentration in postprandial plasma with the GMP diet compared with the AA diet. When comparing fasting with postprandial plasma, plasma phenalyalanine concentration increased significantly with the AA but not with the GMP diet. Blood urea nitrogen was significantly lower, which suggests decreased ureagenesis, and plasma insulin was higher with the GMP diet than with the AA diet. CONCLUSIONS GMP, when supplemented with limiting AAs, is a safe and highly acceptable alternative to synthetic AAs as the primary protein source in the nutritional management of PKU. As an intact protein source, GMP improves protein retention and phenylalanine utilization compared with AAs.
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Tharakan JF, Yu YM, Zurakowski D, Roth RM, Young VR, Castillo L. Adaptation to a long term (4 weeks) arginine- and precursor (glutamate, proline and aspartate)-free diet. Clin Nutr 2008; 27:513-22. [PMID: 18590940 DOI: 10.1016/j.clnu.2008.04.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Accepted: 04/25/2008] [Indexed: 11/28/2022]
Abstract
BACKGROUND & AIMS It is not known whether arginine homeostasis is negatively affected by a "long term" dietary restriction of arginine and its major precursors in healthy adults. To assess the effects of a 4-week arginine- and precursor-free dietary intake on the regulatory mechanisms of arginine homeostasis in healthy subjects. METHODS Ten healthy adults received a complete amino acid diet for 1 week (control diet) and following a break period, six subjects received a 4-week arginine, proline, glutamate and aspartate-free diet (APF diet). The other four subjects continued for 4 weeks with the complete diet. On days 4 and 7 of the first week and days 25 and 28 of the 4-week period, the subjects received 24-h infusions of arginine, citrulline, leucine and urea tracers. RESULTS During the 4-week APF, plasma arginine fluxes for the fed state, were significantly reduced. There were no significant differences for citrulline, leucine or urea fluxes. Arginine de novo synthesis was not affected by the APF intake. However, arginine oxidation was significantly decreased. CONCLUSIONS In healthy adults, homeostasis of arginine under a long term arginine- and precursor-free intake is achieved by decreasing catabolic rates, while de novo arginine synthesis is maintained.
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Affiliation(s)
- John F Tharakan
- Laboratory of Human Nutrition and Clinical Research Center, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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Fouillet H, Juillet B, Bos C, Mariotti F, Gaudichon C, Benamouzig R, Tomé D. Urea-nitrogen production and salvage are modulated by protein intake in fed humans: results of an oral stable-isotope-tracer protocol and compartmental modeling. Am J Clin Nutr 2008; 87:1702-14. [PMID: 18541559 DOI: 10.1093/ajcn/87.6.1702] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The influence of protein source on postprandial urea kinetics is poorly understood, despite its nutritional significance with respect to nitrogen homeostasis. Furthermore, traditional tracer infusion studies underestimate acute postprandial change in urea kinetics. OBJECTIVE We investigated postprandial, non-steady state urea kinetics and their modulation by qualitative and quantitative factors of protein intake by the combined use of robust clinical data on nitrogen postprandial distribution and mathematical modeling. DESIGN In healthy subjects standardized to a normal protein intake for 7 d, dietary and total nitrogen kinetics were measured for 8 h in plasma proteins, body, and urinary urea after the ingestion of a (15)N-labeled milk (n = 8), soy (n = 8), or wheat (n = 8) protein meal. In subjects who received the soy protein meal, these postprandial measurements were repeated after a further 7-d adaptation to a high protein intake. A 4-compartment model was developed to calculate from these data the postprandial kinetics of production, urinary excretion, and intestinal hydrolysis of urea nitrogen from both dietary and endogenous sources. RESULTS Urinary urea excretion was not influenced by the protein source in the meal but was influenced by the protein level in the diet. By contrast, urea production and hydrolysis were higher when ingesting plant versus animal protein, together with a higher efficiency of urea hydrolysis (50-60% versus 25% of the urea produced being hydrolyzed, respectively). CONCLUSIONS We conclude that urea hydrolysis is an acute nitrogen-sparing mechanism that can counterbalance a postprandial higher urea production, and the efficiency of this recycling is higher when the usual protein intake is lower.
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Affiliation(s)
- Hélène Fouillet
- INRA, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France.
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Juillet B, Fouillet H, Bos C, Mariotti F, Gausserès N, Benamouzig R, Tomé D, Gaudichon C. Increasing habitual protein intake results in reduced postprandial efficiency of peripheral, anabolic wheat protein nitrogen use in humans. Am J Clin Nutr 2008; 87:666-78. [PMID: 18326606 DOI: 10.1093/ajcn/87.3.666] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The postprandial retention of dietary protein decreases when the prevailing protein intake increases. OBJECTIVE We investigated the influence of the prevailing protein intake on the regional utilization and anabolic use of wheat protein during the postprandial non-steady state in humans. DESIGN Healthy adults (n = 8) were adapted for 7 d, first to a normal-protein diet (NP: 1 g x kg(-1) x d(-1)) and then to a high-protein diet (HP: 2 g x kg(-1) x d(-1)). After each adaptation period, the subjects received the same single, solid mixed meal containing [15N]-labeled wheat protein. The postprandial kinetics of dietary nitrogen were then measured for 8 h in blood and urine. These data were further analyzed by using a multicompartmental model to predict the postprandial kinetics of dietary nitrogen in unsampled pools. RESULTS The postprandial whole-body retention of wheat protein nitrogen, measured 8 h after meal ingestion, decreased by 10% when the subjects switched from the NP diet to the HP diet. According to modeling results, this resulted from an increased splanchnic utilization of dietary nitrogen for urea production, whereas its incorporation into splanchnic proteins was unchanged, leading to a 20-30% decrease in peripheral availability and anabolic use in HP-adapted compared with NP-adapted subjects having ingested the same protein load. CONCLUSIONS By combining clinical experimentation with compartmental modeling, we provide a global overview of postprandial dietary protein metabolism. Increasing prior protein intake was shown to reduce the postprandial retention of wheat protein nitrogen, mainly by diminishing the efficiency of its peripheral availability and anabolic use.
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Affiliation(s)
- Barbara Juillet
- INRA, AgroParisTech, UMR914 Nutrition Physiology and Ingestive Behavior, CRNH-IdF, Paris, France
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Nutritional status of adventure racers. Nutrition 2007; 23:404-11. [PMID: 17383160 DOI: 10.1016/j.nut.2007.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 12/07/2006] [Accepted: 01/04/2007] [Indexed: 11/29/2022]
Abstract
OBJECTIVE We describe the usual food intake, body composition, and biochemical profile of adventure racers during their training season and evaluate their energy and nutrient intake in relation to current recommendations for ultraendurance athletes. METHODS Twenty-four adventure race athletes (18 men and 6 women), 24 to 42 y of age, participated in the study. Food intake was determined with a 3-d food record and body composition by plethysmography. Blood samples were obtained from all subjects for biochemical analyses. All assessments were made during the usual training phase. RESULTS Female athletes had a higher body fat percentage than did male athletes (20.2 +/- 5.7% versus 12.5 +/- 3.5%). For men and women, food intake was high in protein (1.9 +/- 0.5 g/kg in men, 2.0 +/- 0.4 g/kg in women) and fat (1.6 +/- 0.3 g/kg in men, 1.5 +/- 1.3 g/kg in women). Carbohydrate intake of male athletes was at the lower limit of that recommended (5.9 +/- 1.8 g/kg). For most vitamins and minerals, athletes' intake was adequate, with the exception of magnesium, zinc, and potassium in men and women and vitamin E and calcium in women, which presented a high probability of being inadequate compared with reference values. High blood levels of total cholesterol and low-density lipoprotein cholesterol were found in female athletes (201.0 +/- 44.7 and 104.1 +/- 43.1 mg/dL, respectively) and all other biochemical analyses were within normal reference values. CONCLUSION The adventure racers presented an inadequate nutritional profile when compared with recommendations for endurance exercise. These athletes need to be educated about consuming an adequate diet to meet the nutritional needs of their activity.
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Löhrke B, Saggau E, Schadereit R, Beyer M, Bellmann O, Kuhla S, Hagemeister H. Activation of skeletal muscle protein breakdown following consumption of soyabean protein in pigs. Br J Nutr 2007; 85:447-57. [PMID: 11348559 DOI: 10.1079/bjn2000291] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Diets with protein of inferior quality may increase protein breakdown in skeletal muscle but the experimental results are inconsistent. To elucidate the relationship, pigs were fed isoenergetic and isonitrogenous diets based on soyabean-protein isolate or casein for 15 weeks, with four to six animals per group. A higher plasma level of urea (2.5-fold the casein group value, P=0.01), higher urinary N excretion (2.1-fold the casein group value, P=0.01), a postabsorptive rise in the plasma levels of urea, 3-methylhistidine and isoleucine in soyabean protein-fed pigs suggested recruitment of circulatory amino acids by protein breakdown in peripheral tissues. Significant differences between dietary groups were detected in lysosomal and ATP-dependent proteolytic activities in the semimembranosus muscle of food-deprived pigs. A higher concentration of cathepsin B protein was found, corresponding to a rise in the cathepsin B activity, in response to dietary soyabean protein. Muscle ATP-stimulated proteolytical activity was 1.6-fold the casein group value (P=0.03). A transient rise in the level of cortisol (2.9-times the casein group value, P=0.02) occurred in the postprandial phase only in the soyabean group. These data suggest that the inferior quality of dietary soyabean protein induces hormonally-mediated upregulation of muscle protein breakdown for recruitment of circulatory amino acids in a postabsorptive state.
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Affiliation(s)
- B Löhrke
- Research Institute for Biology of Farm Animals, Dummerstorf-Rostock, Department of Animal Nutrition, Germany.
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Castellanos VH, Litchford MD, Campbell WW. Modular protein supplements and their application to long-term care. Nutr Clin Pract 2007; 21:485-504. [PMID: 16998147 DOI: 10.1177/0115426506021005485] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Modular protein supplements are added to either the diet or enteral formula to increase the protein or amino acid intakes of people who are nutritionally compromised. Protein supplements are aggressively marketed to long-term care clinicians because protein energy malnutrition and wounds are a common problem in this care setting. It can be challenging for clinicians to distinguish one product from another and to determine the best product for a specific application or nutrition care goal. Modular protein products can be sorted into 4 categories: (1) protein concentrates derived from a complete protein such as milk, soy, or eggs; (2) protein concentrates derived from collagen, either alone or in combination with a complete protein; (3) doses of 1 or more dispensable (nonessential) amino acids; and (4) hybrids of the complete or collagen-based proteins and amino acid dose. Modular protein supplements are generally provided either as a substrate for protein synthesis or as a source of 1 or more amino acids that may be conditionally indispensable (conditionally essential) under certain disease conditions. This review provides guidelines for the use of modular protein supplements according to their intended physiologic function and the assessment and nutrition care goals of the long-term care resident.
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Ingenbleek Y. The nutritional relationship linking sulfur to nitrogen in living organisms. J Nutr 2006; 136:1641S-1651S. [PMID: 16702334 DOI: 10.1093/jn/136.6.1641s] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nitrogen (N) and sulfur (S) coexist in the biosphere as free elements or in the form of simple inorganic NO3- and SO4(2-) oxyanions, which must be reduced before undergoing anabolic processes leading to the production of methionine (Met) and other S-containing molecules. Both N and S pathways are tightly regulated in plant tissues so as to maintain S:N ratios ranging from 1:20 to 1:35. As a result, plant products do not adequately fulfill human tissue requirements, whose mean S:N ratios amount to 1:14.5. The evolutionary patterns of total body N (TBN) and of total body S (TBS) offer from birth to death sex- and age-related specificities well identified by the serial measurement of plasma transthyretin (TTR). Met is regarded as the most limiting of all indispensable amino acids (IAAs) because of its participation in a myriad of molecular, structural, and metabolic activities of survival importance. Met homeostasis is regulated by subtle competitive interactions between transsulfuration and remethylation pathways of homocysteine (Hcy) and by the actual level of TBN reserves working as a direct sensor of cystathionine-beta-synthase activity. Under steady-state conditions, the dietary intake of SO4(2-) is essentially equal to total sulfaturia. The recommended dietary allowances for both S-containing AAs allotted to replace the minimal obligatory losses resulting from endogenous catabolism is largely covered by Western customary diets. By contrast, strict vegans and low-income populations living in plant-eating countries incur the risk of chronic N and Met dietary deficiencies causing undesirable hyperhomocysteinemia best explained by the downsizing of their TBN resources and documented by declining TTR plasma values.
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Affiliation(s)
- Yves Ingenbleek
- Laboratory of Nutrition, Faculty of Pharmacy, University Louis-Pasteur, Strasbourg, France.
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41
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Martin WF, Cerundolo LH, Pikosky MA, Gaine PC, Maresh CM, Armstrong LE, Bolster DR, Rodriguez NR. Effects of dietary protein intake on indexes of hydration. ACTA ACUST UNITED AC 2006; 106:587-9. [PMID: 16567155 DOI: 10.1016/j.jada.2006.01.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Indexed: 11/28/2022]
Abstract
This study aims to characterize the relationship between increased protein intake and hydration indexes. Five men participated in a 12-week, randomized, crossover, controlled diet intervention study. Subjects consumed eucaloric diets containing 3.6 (high protein), 1.8 (moderate protein), and 0.8 (low protein) g/kg/day of protein for 4 weeks each. Energy intakes were based on requirements established relative to resting energy expenditure and activity at baseline. Assessments included blood urea nitrogen, plasma osmolality, urine-specific gravity, and estimates of fluid balance. Repeated-measures analyses of variance and paired t tests were used to determine effects of treatment and time. Fluid intake and fluid balance were unaffected. Blood urea nitrogen was higher for high protein vs low protein and vs moderate protein, and urine-specific gravity was higher for high protein vs moderate protein. Baseline plasma osmolality was greater for high protein vs low protein and vs moderate protein. The effect of increasing dietary protein on fluid status was minimal.
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Affiliation(s)
- William F Martin
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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42
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Balter V, Simon L, Fouillet H, Lécuyer C. Box-modeling of 15N/14N in mammals. Oecologia 2005; 147:212-22. [PMID: 16328553 DOI: 10.1007/s00442-005-0263-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 08/30/2005] [Indexed: 11/29/2022]
Abstract
The 15N/14N signature of animal proteins is now commonly used to understand their physiology and quantify the flows of nutrient in trophic webs. These studies assume that animals are predictably 15N-enriched relative to their food, but the isotopic mechanism which accounts for this enrichment remains unknown. We developed a box model of the nitrogen isotope cycle in mammals in order to predict the 15N/14N ratios of body reservoirs as a function of time, N intake and body mass. Results of modeling show that a combination of kinetic isotope fractionation during the N transfer between amines and equilibrium fractionation related to the reversible conversion of N-amine into ammonia is required to account for the well-established approximately 4 per thousand 15N-enrichment of body proteins relative to the diet. This isotopic enrichment observed in proteins is due to the partial recycling of 15N-enriched urea and the urinary excretion of a fraction of the strongly 15N-depleted ammonia reservoir. For a given body mass and diet delta15N, the isotopic compositions are mainly controlled by the N intake. Increase of the urea turnover combined with a decrease of the N intake lead to calculate a delta15N increase of the proteins, in agreement with the observed increase of collagen delta15N of herbivorous animals with aridity. We further show that the low delta15N collagen values of cave bears cannot be attributed to the dormancy periods as it is commonly thought, but inversely to the hyperphagia behavior. This model highlights the need for experimental investigations performed with large mammals in order to improve our understanding of natural variations of delta15N collagen.
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Affiliation(s)
- Vincent Balter
- UMR 5125 CNRS-Lyon1 PaléoEnvironnements et PaléobioSphère, Université Claude Bernard, Campus de la Doua, Bâtiment Géode, Bd du 11/11/1918, 69622 Villeurbanne Cedex, France.
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43
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Martin WF, Armstrong LE, Rodriguez NR. Dietary protein intake and renal function. Nutr Metab (Lond) 2005; 2:25. [PMID: 16174292 PMCID: PMC1262767 DOI: 10.1186/1743-7075-2-25] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 09/20/2005] [Indexed: 01/13/2023] Open
Abstract
Recent trends in weight loss diets have led to a substantial increase in protein intake by individuals. As a result, the safety of habitually consuming dietary protein in excess of recommended intakes has been questioned. In particular, there is concern that high protein intake may promote renal damage by chronically increasing glomerular pressure and hyperfiltration. There is, however, a serious question as to whether there is significant evidence to support this relationship in healthy individuals. In fact, some studies suggest that hyperfiltration, the purported mechanism for renal damage, is a normal adaptative mechanism that occurs in response to several physiological conditions. This paper reviews the available evidence that increased dietary protein intake is a health concern in terms of the potential to initiate or promote renal disease. While protein restriction may be appropriate for treatment of existing kidney disease, we find no significant evidence for a detrimental effect of high protein intakes on kidney function in healthy persons after centuries of a high protein Western diet.
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Affiliation(s)
- William F Martin
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT, USA
| | | | - Nancy R Rodriguez
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT, USA
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Tipton KD, Elliott TA, Cree MG, Wolf SE, Sanford AP, Wolfe RR. Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise. Med Sci Sports Exerc 2005; 36:2073-81. [PMID: 15570142 DOI: 10.1249/01.mss.0000147582.99810.c5] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Determination of the anabolic response to exercise and nutrition is important for individuals who may benefit from increased muscle mass. Intake of free amino acids after resistance exercise stimulates net muscle protein synthesis. The response of muscle protein balance to intact protein ingestion after exercise has not been studied. This study was designed to examine the acute response of muscle protein balance to ingestion of two different intact proteins after resistance exercise. METHODS Healthy volunteers were randomly assigned to one of three groups. Each group consumed one of three drinks: placebo (PL; N = 7), 20 g of casein (CS; N = 7), or whey proteins (WH; N = 9). Volunteers consumed the drink 1 h after the conclusion of a leg extension exercise bout. Leucine and phenylalanine concentrations were measured in femoral arteriovenous samples to determine balance across the leg. RESULTS Arterial amino acid concentrations were elevated by protein ingestion, but the pattern of appearance was different for CS and WH. Net amino acid balance switched from negative to positive after ingestion of both proteins. Peak leucine net balance over time was greater for WH (347 +/- 50 nmol.min(-1).100 mL(-1) leg) than CS (133 +/- 45 nmol.min(-1).100 mL(-1) leg), but peak phenylalanine balance was similar for CS and WH. Ingestion of both CS and WH stimulated a significantly larger net phenylalanine uptake after resistance exercise, compared with the PL (PL -5 +/- 15 mg, CS 84 +/- 10 mg, WH 62 +/- 18 mg). Amino acid uptake relative to amount ingested was similar for both CS and WH (approximately 10-15%). CONCLUSIONS Acute ingestion of both WH and CS after exercise resulted in similar increases in muscle protein net balance, resulting in net muscle protein synthesis despite different patterns of blood amino acid responses.
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Affiliation(s)
- Kevin D Tipton
- Metabolism Unit, Shriners Hospitals for Children and Department of Surgery, The University of Texas Medical Branch, Galveston, TX 77550, USA.
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Lacroix M, Gaudichon C, Martin A, Morens C, Mathé V, Tomé D, Huneau JF. A long-term high-protein diet markedly reduces adipose tissue without major side effects in Wistar male rats. Am J Physiol Regul Integr Comp Physiol 2004; 287:R934-42. [PMID: 15155276 DOI: 10.1152/ajpregu.00100.2004] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Although there is a considerable interest of high-protein, low-carbohydrate diets to manage weight control, their safety is still the subject of considerable debate. They are suspected to be detrimental to the renal and hepatic functions, calcium balance, and insulin sensitivity. However, the long-term effects of a high-protein diet on a broad range of parameters have not been investigated. We studied the effects of a high-protein diet in rats over a period of 6 mo. Forty-eight Wistar male rats received either a normal-protein (NP: 14% protein) or high-protein (HP: 50% protein) diet. Detailed body composition, plasma hormones and nutrients, liver and kidney histopathology, hepatic markers of oxidative stress and detoxification, and the calcium balance were investigated. No major alterations of the liver and kidneys were found in HP rats, whereas NP rats exhibited massive hepatic steatosis. The calcium balance was unchanged, and detoxification markers (GSH and GST) were enhanced moderately in the HP group. In contrast, HP rats showed a sharp reduction in white adipose tissue and lower basal concentrations of triglycerides, glucose, leptin, and insulin. Our study suggests that the long-term consumption of an HP diet in male rats has no deleterious effects and could prevent metabolic syndrome.
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Affiliation(s)
- Magali Lacroix
- Unité INRA 914 Physiologie de la Nutrition et Comportement Alimentaire, INA PG, 16 rue Claude Bernard, 75231 Paris Cedex 05, France
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Veeneman JM, Kingma HA, Stellaard F, de Jong PE, Reijngoud DJ, Huisman RM. Comparison of amino acid oxidation and urea metabolism in haemodialysis patients during fasting and meal intake. Nephrol Dial Transplant 2004; 19:1533-41. [PMID: 15069181 DOI: 10.1093/ndt/gfh236] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The PNA (protein equivalent of nitrogen appearance) is used to calculate protein intake from urea kinetics. One of the essential assumptions in the calculation of PNA is that urea accumulation in haemodialysis (HD) patients is equivalent to amino acid oxidation. However, urea is hydrolysed in the intestine and the resulting ammonia could be used metabolically. The magnitude and dependence on protein intake of this process are unknown in HD patients. METHODS Seven HD patients were studied twice, 1 week apart, on a similar protocol. After an overnight fast, patients fasted in the morning and received meals in the afternoon. On one day, amino acid oxidation was measured by infusion of L-[1-(13)C]valine. Urea production, measured from the dilution of [(13)C]urea, and urea accumulation, calculated from the increase in plasma urea concentration multiplied by the urea dilution volume, were measured during the other day. PNA was calculated using standard equations. RESULTS Amino acid oxidation and urea production were not significantly different during fasting. Urea accumulation during fasting was significantly lower than both amino acid oxidation and urea production. Urea accumulation during feeding remained significantly lower than amino acid oxidation. PNA was equal to the average of the urea accumulation values during fasting and feeding. CONCLUSION We conclude that during fasting, urea accumulation is not associated with amino acid oxidation or urea production. During meal intake, amino acid oxidation, urea production and urea accumulation show acutely an almost identical increase. PNA represents the average of fasting and fed urea accumulation and is lower than average amino acid oxidation or urea production.
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Affiliation(s)
- Jorden M Veeneman
- Department of Internal Medicine, Division of Nephrology, University Hospital Groningen and Groningen University Institute of Drug Exploration, The Netherlands
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Faber P, Johnstone AM, Gibney ER, Elia M, Stubbs RJ, Roger PL, Milne E, Buchan W, Lobley GE. The effect of rate and extent of weight loss on urea salvage in obese male subjects. Br J Nutr 2003; 90:221-31. [PMID: 12844395 DOI: 10.1079/bjn2003859] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It is well established that in human subjects a proportion of urea production undergoes hydrolysis in the gastrointestinal tract with release of N potentially available for amino acid synthesis. Previous studies have suggested adaptive changes in urea kinetics, with more urea-N retained within the metabolic pool during reduced dietary intakes of energy and protein. We therefore investigated the effect of rate and extent of weight loss on adaptive changes in urea kinetics in two groups (each n 6) of obese men (mean age 43 (sd 12) years, BMI 34.8 (sd 2.9) kg/m(2)) during either total starvation for 6 d or a very-low-energy diet (2.55 MJ/d) for 21 d. Subjects were resident in the Human Nutrition Unit of the Rowett Research Institute (Aberdeen, Scotland, UK) and lost 6 and 9 % initial body weight within the starvation and dieting groups respectively. Changes in urea-N metabolism were assessed by stable isotope tracer kinetics using [(15)N(15)N]urea infused intravenously for 36 h before, during and after weight loss. In response to weight loss, urea production decreased (P<0.01) by 25 % from 278 to 206 micromol urea-N/h per kg within the dieting group only. However, no changes were observed in the proportion of urea being hydrolysed in the gastrointestinal tract (range 20-25 %) or in the proportion of N retained for anabolic purposes (80-85 % urea-N from gastrointestinal hydrolysis) within either group. It was concluded that no adaptive changes in urea kinetics occurred in response to either the different rate or extent of weight loss.
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Affiliation(s)
- Peter Faber
- Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, Scotland, UK.
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Singer MA. Do mammals, birds, reptiles and fish have similar nitrogen conserving systems? Comp Biochem Physiol B Biochem Mol Biol 2003; 134:543-58. [PMID: 12670782 DOI: 10.1016/s1096-4959(03)00027-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Comparative physiological studies are a powerful tool for revealing common animal adaptations. Amino acid catabolism produces ammonia which is detoxified through the synthesis of urea (mammals, some fish), uric acid (birds), or urea and uric acid (reptiles). In mammalian herbivores and omnivores, urea nitrogen is salvaged by a series of steps involving urea transfer into the intestine, microbial mediated urea hydrolysis with synthesis of amino acids utilizing the liberated ammonia and transfer of the amino acids back to the host. A similar series of steps occur in omnivorous/granivorous and herbivorous birds, although in this case urine, containing uric acid, is refluxed directly into the intestine where microbes degrade the uric acid and utilize the liberated ammonia for amino acid synthesis. These amino acids are transferred back to the host. In reptiles and ureotelic fish not all of these steps have been experimentally confirmed. Reptiles like birds, reflux urine into the intestine where it is exposed to the microflora. However, the capacity of these microbes to breakdown the uric acid and urea and utilize ammonia for amino acid synthesis has not been documented. Ureotelic fish transfer urea into the intestine where urease (presumably of bacterial origin) hydrolyzes the urea. However, the amino acid synthesizing capacity of the intestinal microflora has not been studied. The series of steps, as outlined, would define the prevailing nitrogen conservation system for herbivores and omnivores at least. However, it would appear that some animals, in particular the fruit-eating bat and perhaps the fruit-eating bird, may have evolved alternative, as yet uncharacterized, adaptations to a very limited nitrogen intake.
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Affiliation(s)
- Michael A Singer
- Department of Medicine, Queen's University, Etherington Hall, Ont., K7L 3N6, Kingston, Canada.
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Kobayashi H, Børsheim E, Anthony TG, Traber DL, Badalamenti J, Kimball SR, Jefferson LS, Wolfe RR. Reduced amino acid availability inhibits muscle protein synthesis and decreases activity of initiation factor eIF2B. Am J Physiol Endocrinol Metab 2003; 284:E488-98. [PMID: 12556349 DOI: 10.1152/ajpendo.00094.2002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have examined the effect of a hemodialysis-induced 40% reduction in plasma amino acid concentrations on rates of muscle protein synthesis and breakdown in normal swine. Muscle protein kinetics were measured by tracer methodology using [(2)H(5)]phenylalanine and [1-(13)C]leucine and analysis of femoral arterial and venous samples and tissue biopsies. Net amino acid release by muscle was accelerated during dialysis. Phenylalanine utilization for muscle protein synthesis was reduced from the basal value of 45 +/- 8 to 25 +/- 6 nmol x min(-1) x 100 ml leg(-1) between 30 and 60 min after start of dialysis and was stimulated when amino acids were replaced while dialysis continued. Muscle protein breakdown was unchanged. The signal for changes in synthesis appeared to be changes in plasma amino acid concentrations, as intramuscular concentrations remained constant throughout. The changes in muscle protein synthesis were accompanied by a reduction or stimulation, respectively, in the guanine nucleotide exchange activity of eukaryotic initiation factor (eIF)2B following hypoaminoacidemia vs. amino acid replacement. We conclude that a reduction in plasma amino acid concentrations below the normal basal value signals an inhibition of muscle protein synthesis and that corresponding changes in eIF2B activity suggest a possible role in mediating the response.
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Affiliation(s)
- Hisamine Kobayashi
- Department of Surgery, Shriners Burns Hospital, University of Texas Medical Branch, Galveston, Texas 77550, USA
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Masud T, Manatunga A, Cotsonis G, Mitch WE. The precision of estimating protein intake of patients with chronic renal failure. Kidney Int 2002; 62:1750-6. [PMID: 12371976 DOI: 10.1046/j.1523-1755.2002.00606.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Biochemical methods for estimating protein intake are based on the concept that nitrogen-containing products of protein in diet plus the products arising from endogenous protein are excreted as either urea or non-urea nitrogen (NUN). This formulation is based on the fact that the urea is the principal end product of amino acid degradation and, hence, the urea appearance rate (or net urea production) is parallel to protein intake. The urea nitrogen appearance (UNA) rate is measured as the amount of urea excreted in urine plus the net amount accumulated in body water. A more difficult problem is how to estimate NUN, the sum of fecal nitrogen, and all forms of non-urea urinary nitrogen. Maroni, Steinman, and Mitch (Kidney Int 27:58-65, 1985) proposed estimating nitrogen intake (IN MARONI) from UNA plus NUN excretion rate of 0.031 g nitrogen/kg body weight/day, as they found NUN correlated with body weight but not with dietary nitrogen. Kopple, Gao, and Qing (Kidney Int 27:486-494, 1997) proposed a different equation for estimating nitrogen intake (IN KOPPLE) = 1.20 UNA + 1.74, concluding that dietary nitrogen directly correlates with fecal nitrogen and that NUN is constant for all patients. Their report prompted us to review all nitrogen balance measurements we had conducted in order to address the following questions. Does dietary protein increase fecal nitrogen excretion? Does NUN vary with weight or is it constant? How do the two methods (IN MARONI and IN KOPPLE) compare in estimating dietary protein from UNA? METHODS We examined nitrogen balance and its components measured in 33 patients with chronic renal failure (CRF) who were eating diets varying from 4.1 to 10.1 g nitrogen/day. We evaluated relationships between dietary nitrogen [intake nitrogen (IN)], NUN, fecal nitrogen, body weight, and the predictability of the two methods. RESULTS Neither fecal nitrogen nor NUN were significantly correlated with IN (r = 0.04 and r = -0.07, respectively). NUN significantly correlated with body weight (P = 0.008). Measured IN averaged 5.75 +/- 0.41 g nitrogen/day; the estimated IN MARONI value was 5.61 +/- 0.27 g nitrogen/day; the estimated IN KOPPLE was 6.04 +/- 0.44 g nitrogen/day. The prediction errors associated with the IN KOPPLE equation were slightly but not statistically higher than that associated with IN MARONI. CONCLUSION Fecal nitrogen is not correlated with IN. NUN is not constant but varies with weight, and the traditional method of estimating IN in stable chronic renal insufficiency (CRI) patients from UNA and weight as proposed by Maroni, Steinman, and Mitch is valid.
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Affiliation(s)
- Tahsin Masud
- Renal Division, Emory University, and Public Health, Emory University, Atlanta, GA 30322, USA
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