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Paoletti A, Pencharz PB, Ball RO, Kong D, Xu L, Elango R, Courtney-Martin G. The dietary requirement for total sulfur amino acids in adults aged ≥60 years appears to be higher in males than in females. Am J Clin Nutr 2023; 118:538-548. [PMID: 37356549 DOI: 10.1016/j.ajcnut.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 05/09/2023] [Accepted: 06/22/2023] [Indexed: 06/27/2023] Open
Abstract
BACKGROUND The total sulfur amino acid (TSAA) recommendation in older adults is based on data from young adults. Physiological evidence suggests that older adults have a higher requirement than young adults. OBJECTIVES The objective of this study was to determine the TSAA requirement in healthy men and women aged ≥60 y. METHODS The TSAA requirement was determined using the indicator amino acid oxidation method with L-[1-13C]phenylalanine as the indicator. At recruitment, 15 older adults (n = 7 men and n = 8 women; BMI < 30 kg/m2) were assigned to receive 7 methionine intakes (5, 10, 15, 19, 25, 35, and 40 mg/kg/d) without dietary cysteine. Intake levels were randomly assigned to each subject. Following enrollment, 2 subjects completed 2 intakes and 3 completed 3, while the remainder completed all 7. Mean TSAA requirement was determined from oxidation of L-[1-13C]phenylalanine using a mixed-effect change-point model. The 95% CI was calculated using parametric bootstrap. To test whether breakpoints were different between men and women, the overlap in the 95% CI was calculated. RESULTS The mean TSAA requirement was 26.2 (Rm2 = 0.39, Rc2 = 0.89; P < 0.001) and 17.1 mg/kg/d (Rm2 = 0.22, Rc2 = 0.79; P < 0.001) for men and women, respectively. The requirement was significantly higher in men than in women (difference in CI: 9.1 ± 8.85). CONCLUSIONS To our knowledge, this is the first study to determine the TSAA requirement in older adults. The requirement in older women is similar to current recommendations but is 75% higher in older men. These findings are important given recommendations for increased plant protein consumption. They will help in the assessment of diet quality and provide the basis of dietary guidelines for older adults consuming a plant-based diet. This trial was registered at clinicaltrials.gov as NCT04595188.
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Affiliation(s)
- Alyssa Paoletti
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Paul B Pencharz
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada; Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Ronald O Ball
- Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Dehan Kong
- Department of Statistical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Libai Xu
- Department of Statistical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Rajavel Elango
- Department of Pediatrics, School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada; BC Children's Hospital Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Glenda Courtney-Martin
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada.
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Ligthart-Melis GC, Engelen MPKJ, Simbo SY, Ten Have GAM, Thaden JJ, Cynober L, Deutz NEP. Metabolic Consequences of Supplemented Methionine in a Clinical Context. J Nutr 2020; 150:2538S-2547S. [PMID: 33000166 DOI: 10.1093/jn/nxaa254] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/01/2020] [Accepted: 07/31/2020] [Indexed: 12/27/2022] Open
Abstract
The central position of methionine (Met) in protein metabolism indicates the importance of this essential amino acid for growth and maintenance of lean body mass. Therefore, Met might be a tempting candidate for supplementation. However, because Met is also the precursor of homocysteine (Hcy), a deficient intake of B vitamins or excessive intake of Met may result in hyperhomocysteinemia (HHcy), which is a risk factor for cardiovascular disease. This review discusses the evidence generated in preclinical and clinical studies on the importance and potentially harmful effects of Met supplementation and elaborates on potential clinical applications of supplemental Met with reference to clinical studies performed over the past 20 y. Recently acquired knowledge about the NOAEL (no observed adverse effect level) of 46.3 mg · kg-1 · d-1 and the LOAEL (lowest observed adverse effect level) of 91 mg · kg-1 · d-1 of supplemented Met will guide the design of future studies to further establish the role of Met as a potential (safe) candidate for nutritional supplementation in clinical applications.
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Affiliation(s)
- Gerdien C Ligthart-Melis
- Center for Translational Research in Aging & Longevity, Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
| | - Mariëlle P K J Engelen
- Center for Translational Research in Aging & Longevity, Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
| | - Sunday Y Simbo
- Center for Translational Research in Aging & Longevity, Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
| | - Gabrie A M Ten Have
- Center for Translational Research in Aging & Longevity, Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
| | - John J Thaden
- Center for Translational Research in Aging & Longevity, Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
| | - Luc Cynober
- Department of Clinical Chemistry, Hôpital Cochin, Hôpitaux Universitaires Paris Centre, Paris, France
| | - Nicolaas E P Deutz
- Center for Translational Research in Aging & Longevity, Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
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3
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Deutz NE, Simbo SY, Ligthart-Melis GC, Cynober L, Smriga M, Engelen MP. Tolerance to increased supplemented dietary intakes of methionine in healthy older adults. Am J Clin Nutr 2017; 106:675-683. [PMID: 28637772 DOI: 10.3945/ajcn.117.152520] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 05/18/2017] [Indexed: 11/14/2022] Open
Abstract
Background: l-Methionine (Met) is an essential amino acid for humans and is important for protein synthesis and the formation of polyamines and is involved in the synthesis of many metabolites, including homocysteine. Free-Met supplements have been claimed to have multiple positive effects; however, it remains unclear what the exact tolerance level is. With aging, Met metabolism changes, and increased plasma homocysteine is more apparent. High plasma concentrations of homocysteine are assumed to be associated with a high risk of developing atherosclerosis.Objective: We estimated the no-observed-adverse-effect level (NOAEL) and the lowest-observed-adverse-effect level (LOAEL) of supplemented, oral, free Met in healthy older adults by examining the increase in plasma homocysteine as the primary determinant.Design: We provided capsules with free Met to 15 healthy older adult subjects for 4 wk at climbing dosages of, on average, 9.2, 22.5, 46.3 and 91 mg · kg body weight-1 · d-1 with washout periods of 2 wk between each intake. Before, at 2 and 4 wk during, and 2 wk after each dosage, we studied a complete panel of biochemical blood variables to detect possible intolerance to increased Met intake. Plasma homocysteine and body composition were measured, and tolerance, quality of life, and cognitive function were assessed via questionnaires.Results: Plasma homocysteine was elevated with the highest dose of supplemented Met. The estimated NOAEL of supplemented Met was set at 46.3 mg · kg body weight-1 · d-1, and the estimated LOAEL of supplemented Met was set at 91 mg · kg body weight-1 · d-1 (on the basis of the actual intakes) in subjects independent of sex. No signs of intolerance were observed via questionnaires or other blood variables at the LOAEL. There were no meaningful changes in body composition.Conclusions: On the basis of plasma homocysteine, the NOAEL of supplemented Met intake is 46.3 and the LOAEL is 91 mg · kg body weight-1 · d-1 in healthy older adults. Both the NOAEL and LOAEL are not associated with meaningful effects on health and wellbeing. This trial was registered at clinicaltrials.gov as NCT02566434.
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Affiliation(s)
- Nicolaas Ep Deutz
- Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX;
| | - Sunday Y Simbo
- Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX
| | - Gerdien C Ligthart-Melis
- Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX
| | - Luc Cynober
- Department of Clinical Chemistry, Cochin and Hotel-Dieu Hospitals, Assistance Publique - Hôpitaux de Paris, Paris, France.,Department of Biological Nutrition, Faculty of Pharmacy, Paris Descartes University, Paris, France; and
| | - Miro Smriga
- International Council on Amino Acid Science, Brussels, Belgium
| | - Mariëlle Pkj Engelen
- Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX
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Mastrototaro L, Sponder G, Saremi B, Aschenbach JR. Gastrointestinal methionine shuttle: Priority handling of precious goods. IUBMB Life 2016; 68:924-934. [DOI: 10.1002/iub.1571] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/22/2016] [Indexed: 01/05/2023]
Affiliation(s)
- Lucia Mastrototaro
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Free University of Berlin; Berlin Germany
| | - Gerhard Sponder
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Free University of Berlin; Berlin Germany
| | - Behnam Saremi
- Evonik Nutrition & Care GmbH; Animal Nutrition-Animal Nutrition Services; Hanau Germany
| | - Jörg R. Aschenbach
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Free University of Berlin; Berlin Germany
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5
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Fitzpatrick AM, Jones DP, Brown LAS. Glutathione redox control of asthma: from molecular mechanisms to therapeutic opportunities. Antioxid Redox Signal 2012; 17:375-408. [PMID: 22304503 PMCID: PMC3353819 DOI: 10.1089/ars.2011.4198] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 01/22/2012] [Accepted: 01/22/2012] [Indexed: 12/11/2022]
Abstract
Asthma is a chronic inflammatory disorder of the airways associated with airway hyper-responsiveness and airflow limitation in response to specific triggers. Whereas inflammation is important for tissue regeneration and wound healing, the profound and sustained inflammatory response associated with asthma may result in airway remodeling that involves smooth muscle hypertrophy, epithelial goblet-cell hyperplasia, and permanent deposition of airway extracellular matrix proteins. Although the specific mechanisms responsible for asthma are still being unraveled, free radicals such as reactive oxygen species and reactive nitrogen species are important mediators of airway tissue damage that are increased in subjects with asthma. There is also a growing body of literature implicating disturbances in oxidation/reduction (redox) reactions and impaired antioxidant defenses as a risk factor for asthma development and asthma severity. Ultimately, these redox-related perturbations result in a vicious cycle of airway inflammation and injury that is not always amenable to current asthma therapy, particularly in cases of severe asthma. This review will discuss disruptions of redox signaling and control in asthma with a focus on the thiol, glutathione, and reduced (thiol) form (GSH). First, GSH synthesis, GSH distribution, and GSH function and homeostasis are discussed. We then review the literature related to GSH redox balance in health and asthma, with an emphasis on human studies. Finally, therapeutic opportunities to restore the GSH redox balance in subjects with asthma are discussed.
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Affiliation(s)
- Anne M Fitzpatrick
- Department of Pediatrics, Emory University, Atlanta, Georgia 30322, USA.
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Study of molecular targets influencing homocysteine and cholesterol metabolism in growing rats by manipulation of dietary selenium and methionine concentrations. Br J Nutr 2010; 104:520-32. [PMID: 20350341 DOI: 10.1017/s0007114510000899] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Inconsistent results exist from human and animal studies for Se and methionine (Met) regarding their influence on homocysteine (HCys) and cholesterol (Chol) metabolism. To elucidate these contradictions, sixty-four weanling albino rats were divided into eight groups of 8, and were fed diets containing four different Se levels (15, 50, 150 and 450 microg/kg) either in combination with the recommended Met level of 3 g/kg (C15, C50, C150 and C450) or with an increased Met concentration of 15 g/kg (M15, M50, M150 and M450) for 8 weeks. Plasma HCys was twofold higher in the Se-supplemented C groups than in group C15. Met addition also doubled plasma HCys compared with the respective C groups. In contrast, the expression of the key enzymes of glutathione biosynthesis in the liver was significantly lowered by Se and in particular by Met. Liver Chol concentration was significantly higher in all the Se-supplemented C and M groups than in groups C15 and M15. Plasma Chol was, however, lowered. The uninfluenced expression of sterol-regulatory element-binding protein 2 and of hydroxymethyl-glutaryl-CoA reductase, the increased LDL receptor expression and the reduced expression of the hepatobiliary Chol exporter ATP-binding-cassette-transporter 8 (ABCG8) by Se and/or Met explain these findings. We conclude that the elevation of plasma HCys in rats by Se and Met results from a higher export into plasma. The fact that Se in particular combined with Met increases liver Chol but reduces plasma Chol should be addressed in future investigations focussing on the regulation of ABCG8, which is also selectively involved in the reverse transport of phytosterols in the small intestine.
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Nimni ME, Han B, Cordoba F. Are we getting enough sulfur in our diet? Nutr Metab (Lond) 2007; 4:24. [PMID: 17986345 PMCID: PMC2198910 DOI: 10.1186/1743-7075-4-24] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 11/06/2007] [Indexed: 01/15/2023] Open
Abstract
Sulfur, after calcium and phosphorus, is the most abundant mineral element found in our body. It is available to us in our diets, derived almost exclusively from proteins, and yet only 2 of the 20 amino acids normally present in proteins contains sulfur. One of these amino acids, methionine, cannot be synthesized by our bodies and therefore has to be supplied by the diet. Cysteine, another sulfur containing amino acid, and a large number of key metabolic intermediates essential for life, are synthesized by us, but the process requires a steady supply of sulfur. Proteins contain between 3 and 6% of sulfur amino acids. A very small percentage of sulfur comes in the form of inorganic sulfates and other forms of organic sulfur present in foods such as garlic, onion, broccoli, etc. The minimal requirements (RDA) for all the essential amino acids have always been estimated in terms of their ability to maintain a nitrogen balance. This method asses amino acid requirements for protein synthesis, only one of the pathways that methionine follows after ingestion. To adequately evaluate the RDA for methionine, one should perform, together with a nitrogen balance a sulfur balance, something never done, neither in humans nor animals. With this in mind we decided to evaluate the dietary intake of sulfur (as sulfur amino acids) in a random population and perform sulfur balance studies in a limited number of human volunteers. Initially this was done to try and gain some information on the possible mode of action of a variety of sulfur containing compounds (chondroitin sulfate, glucosamine sulfate, and others, ) used as dietary supplements to treat diseases of the joints. Out of this study came information that suggested that a significant proportion of the population that included disproportionally the aged, may not be receiving sufficient sulfur and that these dietary supplements, were very likely exhibiting their pharmacological actions by supplying inorganic sulfur.
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Affiliation(s)
- Marcel E Nimni
- Departments of Surgery and Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, USA.
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8
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Velez-Carrasco W, Merkel M, Twiss CO, Smith JD. Dietary methionine effects on plasma homocysteine and HDL metabolism in mice. J Nutr Biochem 2007; 19:362-70. [PMID: 17707632 PMCID: PMC2430472 DOI: 10.1016/j.jnutbio.2007.05.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 05/17/2007] [Indexed: 01/07/2023]
Abstract
The effects of dietary manipulation of folate and methionine on plasma homocysteine (Hcy) and high-density lipoprotein cholesterol (HDL-C) levels in wild-type and apolipoprotein-E-deficient mice were determined. A low-folate diet with or without folate and/or methionine supplementation in drinking water was administered for 7 weeks. Fasted Hcy rose to 23 microM on a low-folate/high-methionine diet, but high folate ameliorated the effect of high methionine on fasted plasma Hcy to approximately 10 microM. Determination of nonfasted plasma Hcy levels at 6-h intervals revealed a large diurnal variation in Hcy consistent with a nocturnal lifestyle. The daily average of nonfasted Hcy levels was higher than fasted values for high-methionine diets but lower than fasted values for low-methionine diets. An acute methionine load by gavage of fasted mice increased plasma Hcy 2.5 h later, but mice that had been on high-methionine diets had a lower fold induction. Mice fed high-methionine diets weighed less than mice fed low-methionine diets. Based on these results, two solid-food diets were developed: one containing 2% added methionine and the other containing 2% added glycine. The methionine diet led to fasted plasma Hcy levels of >60 microM, higher than those with methionine supplementation in drinking water. Mice on methionine diets had >20% decreased body weights and decreased HDL-C levels. An HDL turnover study demonstrated that the HDL-C production rate was significantly reduced in mice fed the methionine diet.
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Affiliation(s)
- Wanda Velez-Carrasco
- Department of Biochemical Genetics and Metabolism, Rockefeller University, New York, NY 10021, USA
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9
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Abstract
The literature has been searched to identify evidence relating to the possible toxicity of the amino acid methionine in human subjects. Nutritional and metabolic studies have employed amounts of methionine, including the d and dl isomers, both below and above the requirement and have not reported adverse effects in adults and children. Although methionine is known to exacerbate psychopathological symptoms in schizophrenic patients, there is no evidence of similar effects in healthy subjects. The role of methionine as a precursor of homocysteine is the most notable cause for concern. A "loading dose" of methionine (0.1 g/kg) has been given, and the resultant acute increase in plasma homocysteine has been used as an index of the susceptibility to cardiovascular disease. Although this procedure results in vascular dysfunction, this is acute and unlikely to result in permanent damage. However, a 10-fold larger dose, given mistakenly, resulted in death. Longer-term studies in adults have indicated no adverse consequences of moderate fluctuations in dietary methionine intake, but intakes higher than 5 times normal resulted in elevated homocysteine levels. These effects of methionine on homocysteine and vascular function are moderated by supplements of vitamins B-6, B-12, C, and folic acid. In infants, methionine intakes of 2-5 times normal resulted in impaired growth and extremely high plasma methionine levels, but no adverse long-term consequences were observed.
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Affiliation(s)
- Peter J Garlick
- Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA.
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10
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Abstract
No direct data exist on the influence of supranormal intakes of sulfur amino acids on immune function in humans. However 3 major products of sulfur amino acids, glutathione (GSH), homocysteine (Hcy), and taurine (Tau), influence, mainly, inflammatory aspects of the immune response in vitro and in vivo. Methionine intakes above approximately 1 g/d transiently raise plasma Tau, Hcy, and GSH. Tau and GSH ameliorate inflammation. Hcy has the opposite effect. A biphasic relation, between cellular GSH and CD4+ and CD8+ numbers occurs in healthy men. How changes in sulfur amino acid intake influence this phenomenon is unknown. In animals, high Tau intakes are antiinflammatory. How immune function in humans is affected is unknown. A positive relation between plasma neopterin (a marker of a Th-1-type immune response) and Hcy indicates that Hcy may play a part in inflammatory aspects of Parkinson's disease and aging. In vitro, Hcy, at concentrations seen following consumption of approximately 6 g L-methionine/d in adults, increases the interactions among T lymphocytes, monocytes, and endothelium. Whether a similar phenomenon occurs in vivo is unknown. Polymorphisms in the methylenetetrahydrofolate reductase gene are associated with raised plasma Hcy in young but not old subjects. The relation of this observation to immune function is unknown. The relationships among Hcy, inflammatory aspects of disease, and in vitro alterations in immune cell behavior create a cautionary note about supplementation of diets with l-methionine to raise intake above approximately 1 g/d. Studies directly linking methionine intake, genetics, plasma Hcy, Tau, and GSH and immune function are needed.
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Affiliation(s)
- Robert F Grimble
- Institute of Human Nutrition, School of Medicine, University of Southampton, Southampton SO16 7PX, UK.
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11
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Fukagawa NK. Sparing of methionine requirements: evaluation of human data takes sulfur amino acids beyond protein. J Nutr 2006; 136:1676S-1681S. [PMID: 16702339 DOI: 10.1093/jn/136.6.1676s] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The intimate relation between amino acids and protein and nitrogen requirements is well recognized. Nutrition research has focused on the capacity of food to meet the need for nitrogen and indispensable amino acids (IAA) and led to the conclusion that the quality, not just the quantity, of protein is critical. This is especially relevant in regard to the sulfur amino acids (SAA) methionine and cysteine because of the increased understanding of their relation to chronic diseases (e.g., cardiovascular disease, dementia, cirrhosis), immunomodulation, DNA transcription, and RNA translation. Considerable effort has been expended to determine whether and to what extent cysteine can spare the requirement for the IAA methionine. In vivo studies in humans generally concur that the dietary requirement of the SAA ranges between 13 and 16 mg.kg(-1).d(-1), but how much can be met by cysteine relative to methionine remains controversial. This review examines the current status of in vivo estimates of methionine and cysteine requirements in human adults and considers needs beyond what is necessary for protein synthesis. Factors influencing the utilization of methionine and cysteine, especially those conditions that lead to toxicity on the one hand or beneficial effects on the other, are discussed. Data on alternative dietary sources of methyl groups (e.g., betaine, choline, phosphatidylcholine, S-adenosylmethionine, S-methylmethionine) or sulfur (e.g., N-acetylcysteine or L-2-oxothiazolidine-4-carboxylic acid) support a role for the SAA "beyond protein." Other pathways may influence the specific requirement for methionine and/or cysteine, especially when the person is challenged by disease, inadequate availability of food, or environmental stress.
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Affiliation(s)
- Naomi K Fukagawa
- Department of Medicine and General Clinical Research Center, University of Vermont College of Medicine, Burlington, Vermont 05405, USA.
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12
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Ditscheid B, Fünfstück R, Busch M, Schubert R, Gerth J, Jahreis G. Effect of L-methionine supplementation on plasma homocysteine and other free amino acids: a placebo-controlled double-blind cross-over study. Eur J Clin Nutr 2005; 59:768-75. [PMID: 15870821 DOI: 10.1038/sj.ejcn.1602138] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
OBJECTIVE The essential amino acid L-methionine is a potential compound in the prophylaxis of recurrent or relapsing urinary tract infection due to acidification of urine. As an intermediate of L-methionine metabolism, homocysteine is formed. The objective was to study the metabolism of L-methionine and homocysteine, and to assess whether there are differences between patients with chronic urinary tract infection and healthy control subjects. DESIGN A randomized placebo-controlled double-blind intervention study with cross-over design. SETTING Department of Nutritional Physiology, Institute of Nutrition in cooperation with the Department of Internal Medicine III, Friedrich Schiller University of Jena, Germany. SUBJECTS Eight female patients with chronic urinary tract infection and 12 healthy women (controls). INTERVENTIONS After a methionine-loading test, the volunteers received 500 mg L-methionine or a placebo three times daily for 4 weeks. MAIN OUTCOME MEASURES Serum and urinary concentrations of methionine, homocysteine, cystathionine, cystine, serine, glycine and serum concentrations of vitamin B12, B6 and the state of folate. RESULTS Homocysteine plasma concentrations increased from 9.4+/-2.7 micromol/l (patients) and 8.9+/-1.8 micromol/l (controls) in the placebo period to 11.2+/-4.1 micromol/l (P=0.031) and 11.0+/-2.3 micromol/l (P=0.000), respectively, during L-methionine supplementation. There were significant increases in serum methionine (53.6+/-22.0 micromol/l; P=0.003; n=20) and cystathionine (0.62+/-0.30 micromol/l; P=0.000; n=20) concentrations compared with the placebo period (33.0+/-12.0 and 0.30+/-0.10 micromol/l; n=20). Simultaneously, renal excretion of methionine and homocysteine was significantly higher during L-methionine intake. CONCLUSIONS Despite an adequate vitamin status, the supplementation of 1500 mg of L-methionine daily significantly increases homocysteine plasma concentrations by an average of 2.0 micromol/l in patients and in control subjects. An optimal vitamin supplementation, especially with folate, might prevent such an increase.
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Affiliation(s)
- B Ditscheid
- Department of Nutritional Physiology, Institute of Nutrition, Friedrich Schiller University of Jena, Jena, Germany
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Verhoef P, van Vliet T, Olthof MR, Katan MB. A high-protein diet increases postprandial but not fasting plasma total homocysteine concentrations: a dietary controlled, crossover trial in healthy volunteers. Am J Clin Nutr 2005. [DOI: 10.1093/ajcn/82.3.553] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Petra Verhoef
- From the Nutrition and Health Programme, Wageningen Centre for Food Sciences, Wageningen, Netherlands (PV, MRO, and MBK); the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands (PV, MBK, and MRO); and the Business Unit Physiological Sciences, TNO Quality of Life, Zeist, Netherlands (TvV)
| | - Trinette van Vliet
- From the Nutrition and Health Programme, Wageningen Centre for Food Sciences, Wageningen, Netherlands (PV, MRO, and MBK); the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands (PV, MBK, and MRO); and the Business Unit Physiological Sciences, TNO Quality of Life, Zeist, Netherlands (TvV)
| | - Margreet R Olthof
- From the Nutrition and Health Programme, Wageningen Centre for Food Sciences, Wageningen, Netherlands (PV, MRO, and MBK); the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands (PV, MBK, and MRO); and the Business Unit Physiological Sciences, TNO Quality of Life, Zeist, Netherlands (TvV)
| | - Martijn B Katan
- From the Nutrition and Health Programme, Wageningen Centre for Food Sciences, Wageningen, Netherlands (PV, MRO, and MBK); the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands (PV, MBK, and MRO); and the Business Unit Physiological Sciences, TNO Quality of Life, Zeist, Netherlands (TvV)
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14
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Verhoef P, van Vliet T, Olthof MR, Katan MB. A high-protein diet increases postprandial but not fasting plasma total homocysteine concentrations: a dietary controlled, crossover trial in healthy volunteers. Am J Clin Nutr 2005; 82:553-8. [PMID: 16155267 DOI: 10.1093/ajcn.82.3.553] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND A high plasma concentration of total homocysteine (tHcy) is associated with increased risk of cardiovascular disease. A high protein intake and hence a high intake of methionine--the sole dietary precursor of homocysteine--may raise plasma tHcy concentrations. OBJECTIVES We studied whether high intake of protein increases plasma concentrations of tHcy in the fasting state and throughout the day. DESIGN We conducted a randomized, dietary controlled, crossover trial in 20 healthy men aged 18-44 y. For 8 d, men consumed a controlled low-protein diet enriched with either a protein supplement [high-protein diet (21% of energy as protein)] or an isocaloric amount of short-chain glucose polymers [low-protein diet (9% of energy as protein)]. After a 13-d washout period, treatments were reversed. On days 1 and 8 of each treatment period, blood was sampled before breakfast (fasting) and throughout the day. RESULTS Fasting tHcy concentrations did not differ significantly after the 1-wk high-protein and the 1-wk low-protein diets. The high-protein diet resulted in a significantly higher area under the 24-h homocysteine-by-time curves compared with the low-protein diet, both on day 1 (difference: 45.1 h x micromol/L; 95% CI: 35.3, 54.8 h x micromol/L; P < 0.0001) and on day 8 (difference: 24.7 h x micromol/L; 95% CI: 15.0, 34.5 h x micromol/L; P < 0.0001). CONCLUSIONS A high-protein diet increases tHcy concentrations throughout the day but does not increase fasting tHcy concentrations. As previously shown, the extent of the tHcy increase is modified by the amino acid composition of the protein diet. The clinical relevance of this finding depends on whether high concentrations of tHcy-particularly postprandially-cause cardiovascular disease.
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Affiliation(s)
- Petra Verhoef
- Nutrition and Health Programme, Wageningen Centre for Food Sciences, Wageningen, The Netherlands.
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