Dietary Intake of Protein from Different Sources and Weight Regain, Changes in Body Composition and Cardiometabolic Risk Factors after Weight Loss: The DIOGenes Study

The relationship between amino acid intake patterns and both general and central obesity

BACKGROUND

Obesity is a threat to public health. Dietary protein and certain amino acids (AAs) have been associated with obesity; however, the association of AAs patterns with excess body weight has not been considered, yet. We aimed to examine the relationship between patterns of AA intake and obesity.

METHODS

This cross-sectional study was conducted on 3197 individuals aged 35 to 70 years. Sociodemographic, medical, physical activity, and anthropometric data were collected. Energy and AAs intake were obtained by food frequency questionnaire (FFQ). Factor analysis was utilized to determine the AA patterns. Using multiple logistic regression analysis, the odds ratio (OR) of obesity was calculated among individuals categorized into tertiles of the AAs patterns.

RESULTS

In this study, three AA patterns were identified. The aromatic pattern consists of phenylalanine, tryptophan, proline, glutamic acid, cysteine, serine, and leucine. Five essential AAs plus tyrosine, aspartic acid, arginine, and glycine were the components of the mixed pattern, and finally, the alanine pattern with high loadings for alanine and histidine was the third one. After adjusting for confounders, individuals in the highest tertile (T3) of the aromatic pattern had lower odds of central obesity compared to those in the lowest tertile (T1) (OR = 0.72, 95% CI: 0.58-0.89; p = 0.003), whereas this association was not observed in the alanine pattern. On the contrary, general obesity showed a positive association in T3 of the alanine pattern in comparison with T1 (OR = 1.65, 95% CI: 1.02-2.67; p = 0.039). Mixed pattern was not associated with any of the obesity types.

CONCLUSIONS

The aromatic pattern intake may have an inverse association with central obesity, and following the alanine pattern my contribute to higher odds of general obesity. However, the elaborate relationship between AAs and adiposity warrants further investigation.

A low-carb diet increases fecal short-chain fatty acids in feces of obese women following a weight-loss program: randomized feeding trial

To compare fecal level of short-chain fatty acid (SCFA) and some serum inflammatory markers between the low-carbohydrate (LCD) and the habitual (HD) diet, subjects were enrolled from our previous study on the effect of LCD vs. HD on gut microbiota in obese women following an energy-restricted diet. Serum interleukin-6 (IL-6) significantly increased in the HD group (p < 0.001). Adjusted for the baseline parameters, fecal level of butyric, propionic, and acetic acid were significantly different between the LCD and HD groups (p < 0.001, p = 0.02, and p < 0.001, respectively). Increase in serum insulin level correlated with decrease in fecal propionic acid by 5.3-folds (95% CI =  - 2.7,  - 0.15, p = 0.04). Increase in serum high sensitive C-reactive protein (hs-CRP) correlated with decrease in the percentage of fecal butyric acid by 25% (p = 0.04). Serum fasting blood sugar (FBS) and insulin showed a significant effect on fecal acetic acid (p = 0.009 and p = 0.01, respectively). Elevated serum FBS and insulin correlated with increase in fecal acetic acid by 2.8 and 8.9-folds (95%CI = 0.34, 1.9 and 1.2, 9.2), respectively. The LCD increased fecal SCFAs and a significant correlation was seen between serum IL-6 and fecal propionic acid level. More studies are needed to reach a concise correlation. Trial registration number: The trial was registered in Iranian ClinicalTrials.gov IRCT20200929048876N3.

Effects of Animal and Vegetable Proteins on Gut Microbiota in Subjects with Overweight or Obesity

The gut microbiota plays a pivotal role in the balance between host health and obesity. The composition of the gut microbiota can be influenced by external factors, among which diet plays a key role. As the source of dietary protein is important to achieve weight loss and gut microbiota modulation, in the literature there is increasing evidence to suggest consuming more plant proteins than animal proteins. In this review, a literature search of clinical trials published until February 2023 was conducted to examine the effect of different macronutrients and dietary patterns on the gut microbiota in subjects with overweight and obesity. Several studies have shown that a higher intake of animal protein, as well as the Western diet, can lead to a decrease in beneficial gut bacteria and an increase in harmful ones typical of obesity. On the other hand, diets rich in plant proteins, such as the Mediterranean diet, lead to a significant increase in anti-inflammatory butyrate-producing bacteria, bacterial diversity and a reduction in pro-inflammatory bacteria. Therefore, since diets rich in fiber, plant protein, and an adequate amount of unsaturated fat may help to beneficially modulate the gut microbiota involved in weight loss, further studies are needed.

Isocaloric Substitution of Plant-Based Protein for Animal-Based Protein and Cardiometabolic Risk Factors in a Multiethnic Asian Population

BACKGROUND

Evidence is accumulating that intake of animal-based and plant-based proteins has different effects on cardiometabolic health, but less is known about the health effect of isocaloric substitution of animal-based and plant-based proteins. Data from Asian populations are limited.

OBJECTIVES

This study aimed to evaluate the effects of isocaloric substitution of total plant-based proteins for total and various animal-based protein food groups and to evaluate the effects of substituting protein from legumes and pulses for various animal-based protein food groups on cardiovascular disease (CVD) risk factors and predicted 10-y CVD risk.

METHODS

We conducted a cross-sectional analysis using data collected from 9211 Singapore residents (aged 21-75 y) from the Singapore Multi-Ethnic Cohort. Data on sociodemographic and lifestyle factors were collected using questionnaires. Dietary intakes were assessed using a validated FFQ. BMI, waist circumference, and blood pressure were measured during a physical examination, and blood samples were collected to measure lipid profiles. Associations were assessed by substitution models using a multiple linear regression analysis.

RESULTS

Isocaloric substitution of total plant-based proteins for total and all specific animal-based protein food groups were associated with lower BMI (β: -0.30; 95% CI: -0.38, -0.22), waist circumference (β: -0.85; 95% CI: -1.04, -0.66), and LDL cholesterol concentrations (β: -0.06; 95% CI: -0.08, -0.05) (P < 0.0056). Replacement of processed meat and processed seafood proteins with total plant-based proteins was associated with improvement in most CVD risk factors and predicted 10-y CVD risk. Replacement of oily fish with legume proteins was associated with lower HDL cholesterol and higher TG concentrations.

CONCLUSIONS

The substitution of plant-based proteins for animal-based proteins, especially from processed meat and processed seafood, was inversely associated with the established CVD risk factors such as BMI, waist circumference, and lipid concentrations and predicted 10-y CVD risk. These findings warrant further investigation in independent studies in other Asian populations.

Associations of percentage energy intake from total, animal and plant protein with overweight/obesity and underweight among adults in Addis Ababa, Ethiopia

OBJECTIVE

This study investigated associations between types and food sources of protein with overweight/obesity and underweight in Ethiopia.

DESIGN

We conducted a cross-sectional dietary survey using a non-quantitative FFQ. Linear regression models were used to assess associations between percentage energy intake from total, animal and plant protein and BMI. Logistic regression models were used to examine the associations of percentage energy intake from total, animal and plant protein and specific protein food sources with underweight and overweight/obesity.

SETTING

Addis Ababa, Ethiopia.

PARTICIPANTS

1624 Ethiopian adults (992 women and 632 men) aged 18-49 years in selected households sampled using multi-stage random sampling from five sub-cities of Addis Ababa.

RESULTS

Of the surveyed adults, 31 % were overweight or obese. The majority of energy intake was from carbohydrate with only 3 % from animal protein. In multivariable-adjusted linear models, BMI was not associated with percentage energy from total, plant or animal protein. Total and animal protein intake were both associated with lower odds of overweight/obesity (OR per 1 % energy increment of total protein 0·92; 95 % CI: 0·86, 0·99; P = 0·02; OR per 1 % energy increment of animal protein 0·89; 95 % CI: 0·82, 0·96; P = 0·004) when substituted for carbohydrate and adjusted for socio-demographic covariates.

CONCLUSION

Increasing proportion of energy intake from total protein or animal protein in place of carbohydrate could be a strategy to address overweight and obesity in Addis Ababa; longitudinal studies are needed to further examine this potential association.

Healthy U.S.-style dietary patterns can be modified to provide increased energy from protein

Background

Dietary patterns developed by the USDA provide modest levels of protein (14–18% energy) within the Acceptable Macronutrient Distribution Range (AMDR) of 10–35% for adults, though diets providing a higher percentage of energy may be beneficial for some individuals. The purpose of this study was to determine if it is feasible to modify the Healthy U.S.-Style Eating Pattern (“HEP”) to provide a higher percentage of energy from protein.

Methods

Using the framework implemented by the USDA in developing the HEP, energy from protein was set at 20%, 25%, and 30%. Amounts of protein foods were proportionally increased while amounts of other foods were adjusted iteratively within specified parameters. The models also disaggregated total meat/poultry into fresh and processed forms to develop patterns maintaining current proportions, current levels, reduced, or no processed meat/poultry. Nutrient intakes were compared with nutrient goals for representative U.S. populations with 2,000 kcal needs (females 19–30 years, males 51–70 years), with 90% of the Recommended Dietary Allowance or Adequate Intake regarded as sufficient.

Results

Dietary patterns with 20% energy from protein were constructed with minor deviations from the current 2,000 kcal HEP. Dietary patterns with 25% energy from protein were constructed for all levels of processed meat/poultry excluding the current proportion model, though relative to the current HEP the constructed patterns reflect substantial reductions in amounts of refined grains and starchy vegetables, and substantial increases in protein foods consumed as beans and peas, seafood, and soy products. It was not possible to develop a pattern with 30% energy from protein without reducing the percentage of energy from carbohydrate below the AMDR or non-compliance with other modeling constraints. Stepwise reductions in processed meat/poultry reduced sodium intake.

Conclusions

It is feasible to develop dietary patterns in a 2,000 kcal diet while mirroring the HEP that meet recommended intakes of nutrients with 20% or 25% energy from protein, though the pattern with 25% energy from protein may be more idealistic than realistic. Reduced levels of processed meat/poultry may translate to lower sodium intake.

A Comparison Study on the Therapeutic Effect of High Protein Diets Based on Pork Protein versus Soybean Protein on Obese Mice

In this study, an obese C57BL/6J mice model was induced to compare the effect of different high protein diets (soybean protein and pork protein) on obesity. The obese mice were randomly divided into four groups: natural recovery (NR), high-fat diet (HF), high soybean protein diet (HSP), and high pork protein diet (HPP) groups. After 12 weeks of dietary intervention, the obesity-related indexes of mice were measured, such as body weight, fat coefficients, blood lipid indexes and so on. Results showed that HSP and HPP decreased the weight and fat coefficients of mice, the levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and leptin (p < 0.05). Soybean protein was shown to be more effective in reducing the weight and fat mass of obese mice, although pork protein seemed to have a better effect on regulating serum triglyceride (TG). In addition, the two high protein diets both alleviated hepatic fat deposition effectively. Furthermore, HPP and HSP decreased the expression of hepatic peroxisome proliferator-activated receptor-γ (PPAR-γ) and increased the protein expression of phosphorylated AMP-activated protein kinase (pAMPK), phosphorylated acetyl CoA carboxylase (pACC), and uncoupling protein 2 (UCP2) (p < 0.05). In conclusion, the study shows that high protein diets based on both pork protein and soybean protein alleviated abdominal obesity in mice effectively by regulating lipid metabolism, probably via the UCP2-AMPK-ACC signaling pathway.

The Isocaloric Substitution of Plant-Based and Animal-Based Protein in Relation to Aging-Related Health Outcomes: A Systematic Review

Plant-based and animal-based protein intake have differential effects on various aging-related health outcomes, but less is known about the health effect of isocaloric substitution of plant-based and animal-based protein. This systematic review summarized current evidence of the isocaloric substitutional effect of plant-based and animal-based protein on aging-related health outcomes. PubMed and Embase databases were searched for epidemiologic observational studies published in English up to 15 March 2021. Studies that included adults ≥18 years old; use of a nutritional substitution model to define isocaloric substitution of plant protein and animal protein; health outcomes covering mortality, aging-related diseases or indices; and reported association estimates with corresponding 95% confidence intervals were included. Nine cohort studies and 3 cross-sectional studies were identified, with a total of 1,450,178 subjects included in this review. Consistent and significant inverse association of substituting plant protein for various animal proteins on all-cause mortality was observed among 4 out of 5 studies with relative risks (RRs) from 0.54 to 0.95 and on cardiovascular disease (CVD) mortality among all 4 studies with RRs from 0.58 to 0.91. Among specific animal proteins, the strongest inverse association on all-cause and CVD mortality was identified when substituting plant protein for red and/or processed meat protein, with the effect mainly limited to bread, cereal, and pasta protein when replacing red meat protein. Isocaloric substitution of plant-based protein for animal-based protein might prevent all-cause and CVD-specific mortality. More studies are needed on this topic, particularly for cancer incidence and other specific aging-related diseases.

Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors. A systematic review and meta-analysis of randomised controlled trials

BACKGROUND AND AIMS

Higher protein (HP) diets may lead to lower cardiometabolic risk, compared to lower protein (LP) diets. This systematic review and meta-analysis aims to investigate the effects of HP versus LP diets on cardiometabolic risk factors in adults, using the totality of the current evidence from randomised controlled trials (RCTs).

METHODS

Systematic searches were conducted in electronic databases, up to November 2020. Random effects meta-analyses were conducted to pool the standardised mean differences (SMD) and 95% confidence intervals (CI). The main outcomes were weight loss, body mass index (BMI), waist circumference, fat mass, systolic and diastolic BP, total cholesterol, HDL-and LDL-cholesterol, triacylglycerol, fasting glucose and insulin, and glycated haemoglobin.

RESULTS

Fifty-seven articles reporting on 54 RCTs were included, involving 4344 participants (65% female, mean age: 46 (SD 10) years, mean BMI: 33 (SD 3) kg/m²), with a mean study duration of 18 weeks (range: 4 to 156 weeks). Compared to LP diets (range protein (E%):10-23%), HP diets (range protein (E%): 20-45%) led to more weight loss (SMD -0.13, 95% CI: -0.23, -0.03), greater reductions in fat mass (SMD -0.14, 95% CI: -0.24, -0.04), systolic BP (SMD -0.12, 95% CI: -0.21, -0.02), total cholesterol (SMD -0.11, 95% CI: -0.19, -0.02), triacylglycerol (SMD -0.22, 95% CI: -0.30, -0.14) and insulin (SMD -0.12, 95% CI: -0.22, -0.03). No significant differences were observed for the other outcomes.

CONCLUSIONS

Higher protein diets showed small, but favourable effects on weight loss, fat mass loss, systolic blood pressure, some lipid outcomes and insulin, compared to lower protein diets.

Associations of Meat and Fish Consumption With Conventional and Radiomics Cardiovascular Magnetic Resonance Phenotypes in the UK Biobank

Background: Greater red and processed meat consumption has been linked to adverse cardiovascular outcomes. However, the impact of these exposures on cardiovascular magnetic resonance (CMR) phenotypes has not been adequately studied.

Objective: We describe novel associations of meat intake with cardiovascular phenotypes and investigate underlying mechanisms through consideration of a range of covariates.

Design: We studied 19,408 UK Biobank participants with CMR data available. Average daily red and processed meat consumption was determined through food frequency questionnaires and expressed as a continuous variable. Oily fish was studied as a comparator, previously associated with favourable cardiac outcomes. We considered associations with conventional CMR indices (ventricular volumes, ejection fraction, stroke volume, left ventricular mass), novel CMR radiomics features (shape, first-order, texture), and arterial compliance measures (arterial stiffness index, aortic distensibility). We used multivariable linear regression to investigate relationships between meat intake and cardiovascular phenotypes, adjusting for confounders (age, sex, deprivation, educational level, smoking, alcohol intake, exercise) and potential covariates on the causal pathway (hypertension, hypercholesterolaemia, diabetes, body mass index).

Results: Greater red and processed meat consumption was associated with an unhealthy pattern of biventricular remodelling, worse cardiac function, and poorer arterial compliance. In contrast, greater oily fish consumption was associated with a healthier cardiovascular phenotype and better arterial compliance. There was partial attenuation of associations between red meat and conventional CMR indices with addition of covariates potentially on the causal pathway, indicating a possible mechanistic role for these cardiometabolic morbidities. However, other associations were not altered with inclusion of these covariates, suggesting importance of alternative biological mechanisms underlying these relationships. Radiomics analysis provided deeper phenotyping, demonstrating association of the different dietary habits with distinct ventricular geometry and left ventricular myocardial texture patterns.

Conclusions: Greater red and processed meat consumption is associated with impaired cardiovascular health, both in terms of markers of arterial disease and of cardiac structure and function. Cardiometabolic morbidities appeared to have a mechanistic role in the associations of red meat with ventricular phenotypes, but less so for other associations suggesting importance of alternative mechanism for these relationships.

Protein Intake and Human Health: Implications of Units of Protein Intake

Understanding the health effects of protein intake is bedeviled by a number of factors, including protein quality and source. In addition, different units, including grams, grams per kilogram body weight (g/kg BW), and percent energy, may contribute to confusion about protein's effects on health, especially BW-based units in increasingly obese populations. We aimed to review the literature and to conduct a modeling demonstration of various units of protein intake in relation to markers of cardiometabolic health. Data from the Framingham Heart Study Offspring (n = 1847; 60.3 y; 62.5% women) and Third Generation (n = 2548; 46.2 y; 55.3% women) cohorts and the NHANES 2003-04 (n = 1625; 46.2 y; 49.7% women) and 2005-06 (n = 1347; 43.7 y; 49.5% women) cycles were used to model cross-sectional associations between 7 protein units (grams, percent energy, g/kg ideal BW, g/kg actual BW, BW-adjusted g/kg actual BW, g/kg lean BW, and g/kg fat-free BW) and 9 cardiometabolic outcomes (fasting glucose, systolic and diastolic blood pressure, total and HDL cholesterol, triglycerides, BMI, waist circumference, and estimated glomerular filtration rate). The literature review indicated the use of myriad units of protein intake, with differential results on cardiometabolic outcomes. The modeling demonstration showed units expressed in BW were confounded by BW, irrespective of outcome. Units expressed in grams, percent energy, and ideal BW showed similar results, with or without adjustment for body size. After adjusting for BW, results of units expressed in BW aligned with results of grams, percent energy, and ideal BW. In conclusion, protein intake in cardiometabolic health appears to depend on protein's unit of expression. Authors should be specific about the use of WHO (g/kg ideal BW) compared with US (g/kg actual BW) units, and ideally use gram or percent energy in observational studies. In populations where overweight/obesity are prevalent, intake based on actual BW should be reevaluated.

Very-Low-Calorie Ketogenic Diets With Whey, Vegetable, or Animal Protein in Patients With Obesity: A Randomized Pilot Study

CONTEXT

We compared the efficacy, safety, and effect of 45-day isocaloric very-low-calorie ketogenic diets (VLCKDs) incorporating whey, vegetable, or animal protein on the microbiota in patients with obesity and insulin resistance to test the hypothesis that protein source may modulate the response to VLCKD interventions.

SUBJECTS AND METHODS

Forty-eight patients with obesity (19 males and 29 females, homeostatic model assessment (HOMA) index ≥ 2.5, aged 56.2 ± 6.1 years, body mass index [BMI] 35.9 ± 4.1 kg/m2) were randomly assigned to three 45-day isocaloric VLCKD regimens (≤800 kcal/day) containing whey, plant, or animal protein. Anthropometric indexes; blood and urine chemistry, including parameters of kidney, liver, glucose, and lipid metabolism; body composition; muscle strength; and taxonomic composition of the gut microbiome were assessed. Adverse events were also recorded.

RESULTS

Body weight, BMI, blood pressure, waist circumference, HOMA index, insulin, and total and low-density lipoprotein cholesterol decreased in all patients. Patients who consumed whey protein had a more pronounced improvement in muscle strength. The markers of renal function worsened slightly in the animal protein group. A decrease in the relative abundance of Firmicutes and an increase in Bacteroidetes were observed after the consumption of VLCKDs. This pattern was less pronounced in patients consuming animal protein.

CONCLUSIONS

VLCKDs led to significant weight loss and a striking improvement in metabolic parameters over a 45-day period. VLCKDs based on whey or vegetable protein have a safer profile and result in a healthier microbiota composition than those containing animal proteins. VLCKDs incorporating whey protein are more effective in maintaining muscle performance.

Losing Weight after Menopause with Minimal Aerobic Training and Mediterranean Diet

Objective: It is a common belief that menopausal women have greater difficulty losing weight. The aim of this study was to assess the efficacy of a Mediterranean diet (MD) to promote weight loss in postmenopausal women. All participants were prescribed a hypocaloric traditional MD, tailored to the individual. Subjects were asked not to begin any kind of physical activity. Body composition was measured at the beginning and after 8 weeks of treatment. In total, 89 women (age 52.8 ± 4.5 years, BMI 30.0 ± 5.2 kg/m², fat mass 31.6 ± 10.5 kg) were divided into two groups: the first group consisted of fertile women over 45 years of age, the second group consisted of those diagnosed as menopausal. All women had an improvement in body composition (fat mass −2.3 ± 2.1 kg, p < 0.001; protein −0.1 ± 0.7 kg, p = 0.190) and blood pressure values. No differences were found between the two groups except for a higher reduction of low-density lipoprotein in the menopausal group (p = 0.035). A positive significant correlation between plant to animal protein ratio and fat-free mass variation was found in the menopausal group. These data suggest that a high adherence to a traditional MD would enable menopausal women to lose fat mass and maintain muscle mass with no significant difference to younger women. Fat mass reduction provides menopausal women with improved cardiovascular and metabolic risk factors.

Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies

OBJECTIVE

To examine and quantify the potential dose-response relation between intake of total, animal, and plant protein and the risk of mortality from all causes, cardiovascular disease, and cancer.

DESIGN

Systematic review and meta-analysis of prospective cohort studies.

DATA SOURCES

PubMed, Scopus, and ISI Web of Science until December 2019, and references of retrieved relevant articles.

STUDY SELECTION

Prospective cohort studies that reported the risk estimates for all cause, cardiovascular, and cancer mortality in adults aged 18 or older.

DATA SYNTHESIS

Random effects models were used to calculate pooled effect sizes and 95% confidence intervals for the highest versus lowest categories of protein intake and to incorporate variation between studies. Linear and non-linear dose-response analyses were done to evaluate the dose-response relations between protein intake and mortality.

RESULTS

32 prospective cohort studies were included in the systematic review and 31 in the meta-analysis. During the follow-up period of 3.5 to 32 years, 113 039 deaths (16 429‬ from cardiovascular disease and 22 303‬ from cancer) occurred among 715 128 participants. Intake of total protein was associated with a lower risk of all cause mortality (pooled effect size 0.94, 95% confidence interval 0.89 to 0.99, I2=58.4%, P<0.001). Intake of plant protein was significantly associated with a lower risk of all cause mortality (pooled effect size 0.92, 95% confidence interval 0.87 to 0.97, I2=57.5%, P=0.003) and cardiovascular disease mortality (pooled hazard ratio 0.88, 95% confidence interval 0.80 to 0.96, I2=63.7%, P=0.001), but not with cancer mortality. Intake of total and animal protein was not significantly associated with risk of cardiovascular disease and cancer mortality. A dose-response analysis showed a significant inverse dose-response association between intake of plant protein and all cause mortality (P=0.05 for non-linearity). An additional 3% energy from plant proteins a day was associated with a 5% lower risk of death from all causes.

CONCLUSIONS

Higher intake of total protein was associated with a lower risk of all cause mortality, and intake of plant protein was associated with a lower risk of all cause and cardiovascular disease mortality. Replacement of foods high in animal protein with plant protein sources could be associated with longevity.

Study protocol for a 9-month randomised controlled trial assessing the effects of almonds versus carbohydrate-rich snack foods on weight loss and weight maintenance

INTRODUCTION

Epidemiological studies indicate an inverse association between nut consumption and body mass index (BMI). However, clinical trials evaluating the effects of nut consumption compared with a nut-free diet on adiposity have reported mixed findings with some studies reporting greater weight loss and others reporting no weight change. This paper describes the rationale and detailed protocol for a randomised controlled trial assessing whether the inclusion of almonds or carbohydrate-rich snacks in an otherwise nut-free energy-restricted diet will promote weight loss during 3 months of energy restriction and limit weight regain during 6 months of weight maintenance.

METHODS AND ANALYSIS

One hundred and thirty-four adults aged 25-65 years with a BMI of 27.5-34.9 kg/m² will be recruited and randomly allocated to either the almond-enriched diet (AED) (15% energy from almonds) or a nut-free control diet (NFD) (15% energy from carbohydrate-rich snack foods). Study snack foods will be provided. Weight loss will be achieved through a 30% energy restriction over 3 months, and weight maintenance will be encouraged for 6 months by increasing overall energy intake by ~120-180 kcal/day (~500-750kJ/day) as required. Food will be self-selected, based on recommendations from the study dietitian. Body composition, resting energy expenditure, total daily energy expenditure (via doubly labelled water), physical activity, appetite regulation, cardiometabolic health, gut microbiome, liver health, inflammatory factors, eating behaviours, mood and personality, functional mobility and pain, quality of life and sleep patterns will be measured throughout the 9-month trial. The effects of intervention on the outcome measures over time will be analysed using random effects mixed models, with treatment (AED or NFD) and time (baseline, 3 months and 9 months) being the between and within factors, respectively in the analysis.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the University of South Australia Human Research Ethics Committee (201436). Results from this trial will be disseminated through publication in peer-reviewed journals, national and international presentations.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12618001861246).

Dietary protein insufficiency: an important consideration in fatty liver disease?

Dietary protein insufficiency has been linked to excessive TAG storage and non-alcoholic fatty liver disease (NAFLD) in developing countries. Hepatic TAG accumulation following a low-protein diet may be due to altered peroxisomal, mitochondrial and gut microbiota function. Hepatic peroxisomes and mitochondria normally mediate metabolism of nutrients to provide energy and substrates for lipogenesis. Peroxisome biogenesis and activities can be modulated by odd-chain fatty acids (OCFA) and SCFA that are derived from gut bacteria, for example, propionate and butyrate. Also produced during amino acid metabolism by peroxisomes and mitochondria, propionate and butyrate concentrations correlate inversely with risk of obesity, insulin resistance and NAFLD. In this horizon-scanning review, we have compiled available evidence on the effects of protein malnutrition on OCFA production, arising from loss in mitochondrial, peroxisomal and gut microbiota function, and its association with lipid accumulation in the liver. The methyl donor amino acid composition of dietary protein is an important contributor to liver function and lipid storage; the presence and abundance of dietary branched-chain amino acids can modulate the composition and metabolic activity of the gut microbiome and, on the other hand, can affect protective OCFA and SCFA production in the liver. In preclinical animal models fed with low-protein diets, specific amino acid supplementation can ameliorate fatty liver disease. The association between low dietary protein intake and fatty liver disease is underexplored and merits further investigation, particularly in vulnerable groups with dietary protein restriction in developing countries.

Impact on cardiometabolic risk of a weight loss intervention with higher protein from lean red meat: Combined results of 2 randomized controlled trials in obese middle-aged and older adults

BACKGROUND

The recognized benefits of a higher protein diet on muscle mass and strength in older adults are tempered by concerns of the potentially negative cardiometabolic impact of dietary sources of animal protein.

OBJECTIVE

The aim of this study was to explore the cardiometabolic impact of 2 weight reduction diets: a higher protein diet, providing balanced portions of lean beef and pork throughout the day, vs. a diet following the Recommended Daily Allowance level of protein in obese middle-aged and older adults.

METHODS

Data from Measuring Eating, Activity and Strength: Understanding the Response-Using Protein and Protein Optimization in Women Enables Results-Using Protein were combined for the present analysis. Subjects were randomly assigned to a 6-month weight loss diet (500 kcal deficit) and prescribed a Recommended Daily Allowance level of protein (0.8 g protein/kg BW), control group, or a higher level of protein (1.2 g protein/kg BW), protein group. For the protein group, lean, high-quality protein was evenly distributed between meals or balanced throughout the day (30 g protein/meal). The following cardiometabolic markers were quantified by nuclear magnetic resonance spectroscopy: lipids, lipoproteins, GlycA, trimethylamine-N-oxide, betaine, branched-chain amino acids, and lipoprotein insulin resistance index scores.

RESULTS

In both groups (control [n = 27] and protein [n = 53]), there were significant (P ≤ .05) changes from baseline in weight loss (-6.2% and -7.2%), distance walked (+53.1 and +75.0 meters), and fasting plasma glucose (-7.5 and -6.2 mg/dL), respectively. At endpoint, protein group had significantly (P ≤ .05) lower triglycerides (-17.3 mg/dL), large very-low-density lipoprotein particle concentration (VLDL-P; -1.2 nmol/L), total low-density lipoprotein particle concentration (LDL-P; -67.8 nmol/L), small LDL-P (-59.4 nmol/L) and lipoprotein insulin resistance index (-5.9), whereas control group had significantly (P ≤ .05) lower GlycA (-13.1 μmol/L), total VLDL-P (-7.9 nmol/L), and small VLDL-P (-7.0 nmol/L). Differences between groups were observed for small VLDL-P (P = .02) and protein intake (P < .0001).

CONCLUSIONS

These findings suggest that a hypocaloric diet with either traditional (0.8 g/kg BW/d) or higher protein (1.2 g/kg BW/d; predominantly from lean red meat) content improves risk markers of cardiovascular disease and type II diabetes in obese middle-aged and older adults. Both diets were also associated with improved physical function, and neither had an adverse impact on cardiometabolic outcomes.

Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality in a Japanese Cohort

IMPORTANCE

Epidemiological evidence regarding the long-term effects of higher dietary protein intake on mortality outcomes in the general population is not clear.

OBJECTIVE

To evaluate the associations between animal and plant protein intake and all-cause and cause-specific mortality.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study included 70 696 participants in the Japan Public Health Center-based Prospective Cohort who were aged 45 to 74 years and had no history of cancer, cerebrovascular disease, or ischemic heart disease at study baseline. Data were collected from January 1, 1995, through December 31, 1999, with follow-up completed December 31, 2016, during which 12 381 total deaths were documented. Dietary intake information was collected through a validated food frequency questionnaire and used to estimate protein intake in all participants. Participants were grouped into quintile categories based on their protein intake, expressed as a percentage of total energy. Data were analyzed from July 18, 2017, through April 10, 2019.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) and 95% CIs for all-cause and cause-specific mortality were estimated using Cox proportional hazards regression models with adjustment for potential confounding factors.

RESULTS

Among the 70 696 participants, 32 201 (45.5%) were men (mean [SD] age, 55.6 [7.6] years) and 38 495 (54.5%) were women (mean [SD] age, 55.8 [7.7] years). Intake of animal protein showed no clear association with total or cause-specific mortality. In contrast, intake of plant protein was associated with lower total mortality, with multivariable-adjusted HRs of 0.89 (95% CI, 0.83-0.95) for quintile 2; 0.88 (95% CI, 0.82-0.95) for quintile 3; 0.84 (95% CI, 0.77-0.92) for quintile 4; and 0.87 (95% CI, 0.78-0.96) for quintile 5, with quintile 1 as the reference category (P = .01 for trend). For cause-specific mortality, this association with plant protein intake was evident for cardiovascular disease (CVD)-related mortality (HRs, 0.84 [95% CI, 0.73-0.96] to 0.70 [95% CI, 0.59-0.83]; P = .002 for trend). Isocaloric substitution of 3% energy from plant protein for red meat protein was associated with lower total (HR, 0.66; 95% CI, 0.55-0.80), cancer-related (HR, 0.61; 95% CI, 0.45-0.82), and CVD-related (HR, 0.58; 95% CI, 0.39-0.86) mortality; substitution for processed meat protein was associated with lower total (HR, 0.54; 95% CI, 0.38-0.75) and cancer-related (HR, 0.50; 95% CI, 0.30-0.85) mortality.

CONCLUSIONS AND RELEVANCE

In this large prospective study, higher plant protein intake was associated with lower total and CVD-related mortality. Although animal protein intake was not associated with mortality outcomes, replacement of red meat protein or processed meat protein with plant protein was associated with lower total, cancer-related, and CVD-related mortality.

The association between total antioxidant capacity and resting metabolic rate (RMR) / respiratory quotient (RQ) in overweight and obese woman

OBJECTIVE

The effect of total antioxidant capacity on resting metabolic rate (RMR) and respiratory quotient (RQ) of overweight and obese woman has been debated globally. Total Antioxidant Capacity may have an independent effect on resting metabolic rate and respiratory quotient.

METHODS AND MATERIALS

A study population of 263 aged 18-50 years participated in this cross-sectional study from the communities of Tehran based on cluster sampling. Dietary intake assessed by using a semi quantitative food frequency questionnaire (FFQ) Demographic questions. Anthropometrics measurements for each participant were done. Dietary total antioxidant capacity (DTAC) was calculated by the 147-item food frequency questionnaire (FFQ) and FRAP assay. Resting metabolic rate and respiratory quotient was measured by Indirect calorimetry.

RESULTS

The mean DTAC of the study participants was 1251.8 (SD 893.60). There was a statistically significant relationship between dietary total antioxidant capacity (DTAC) and respiratory quotient (P > 0.013). People with high dietary total antioxidant capacity have tended to show a lower RQ than those with a lower one. There was a significant correlation between DTAC and RQ for both the adjusted model for age, total energy intake, BMI, physical activity, higher DTAC diet and the crude model which were (β = 0.011; SE = 0.005; CI = -0.021_0) and (β = -3.143E-6; SE = 0; CI = 0), respectively. However, we found no correlation between the DTAC and RMR/FFM-RES (P < 0.49). Also, a significantly higher relationship was demonstrated between dietary total antioxidant capacity and intake vegetables (P ≤ 0.006), fruits (P ≤ 0.009), white meet (P ≤ 0.03) and dairy products (P ≤ 0.005).

CONCLUSION

RQ is correlated with total antioxidant capacity. Increased intake of high DTAC foods may result in weight loss maintenance. This result may suggest a beneficial role of higher-DTAC diets in the prevention of obesity.

Meals based on cod or veal in combination with high or low glycemic index carbohydrates did not affect diet-induced thermogenesis, appetite sensations, or subsequent energy intake differently

The objective of this study was to investigate the acute effects of meals containing protein from either cod or veal in combination with high or low glycemic index (GI) carbohydrates, on diet-induced thermogenesis (DIT) (primary endpoint), appetite, energy intake (EI), as well as postpranidal ghrelin, glucose, and insulin responses. Twenty-three overweight men and women (mean ± SD age: 30.0 ± 7.6 y, BMI: 27.2 ± 1.4 kg/m²) consumed 4 test meals: cod with mashed potatoes (high GI carbohydrate), cod with wholegrain pasta (low GI carbohydrate), veal with mashed potatoes, and veal with wholegrain pasta (∼2010 kJ, ∼25.5 E% protein, ∼41.0 E% carbohydrate, ∼33.5 E% fat). Energy expenditure was measured at baseline and six times postprandially, each lasting 25 min. Additionally, appetite sensations were measured every half hour. Arterialized venous blood samples were drawn every 20 min until an ad libitum buffet-style lunch was served 3.5 h later. DIT did not differ between test meals (P > 0.05), and there were no differences in appetite sensations or ad libitum EI (all, P > 0.05). Meal-time interactions were found for glucose and insulin (P = 0.04 and P < 0.001). Pairwise comparisons revealed that glucose and insulin peaks were higher after the meals with high GI carbohydrates. No differences were found between meals with cod or veal in combination with carbohydrates with low or high GI on DIT, appetite sensations, or EI in overweight men and women. However, as expected meals with high GI carbohydrates resulted in higher glucose and insulin responses compared to meals with low GI carbohydrates regardless of protein source.

'Say no': a feasibility trial of a brief intervention to reduce instances of indulgent energy-intake episodes

The aim of this study is to examine the feasibility of a brief intervention to reduce instances of indulgent energy intake. Forty-five participants with a body mass index (BMI) ≥25 kg m-² were randomized to one of three groups for 8 weeks. The control group was asked to complete a questionnaire every 4 days, the self-monitoring group was given the same instructions but also asked to 'say no' to indulgences. The self-monitoring and feedback group was asked to do the same but in addition to send a photograph or description of that to which they had 'said no' and were then provided with feedback. All participants reported on indulgences for 7 days prospectively at baseline and 8-week follow-up. The follow-up rate was 80%; completion of questionnaires was 63% and 87 text messages were sent. The control group reduced their indulgences by 4.1 (SD 10.0), the self-monitoring group by 13.8 (SD 16.8) and self-monitoring and feedback group by 9.0 (SD 11.7) per week. All bar one, feasibility progression criteria were met and this was the return of the indulgence diaries during the intervention period. The study demonstrates the feasibility of a brief intervention to reduce the number of indulgences people ate. The progression criteria were met and areas of improvement are highlighted.

Dietary protein and changes in markers of cardiometabolic health across 20 years of follow-up in middle-aged Americans

OBJECTIVE

Dietary protein plays a role in counteracting age-related muscle loss. However, limited long-term data exist on protein intake and markers of cardiometabolic health, which tend to deteriorate with age.

DESIGN

Prospective cohort study. FFQ-derived protein intake (g/d) and cardiometabolic markers were assessed up to five times across 20 years. Markers included systolic (SBP) and diastolic (DBP) blood pressures, circulating lipids (total, HDL and LDL cholesterol; TAG), estimated glomerular filtration rate (eGFR), fasting glucose (FG), weight and waist circumference (WC). Mixed models accounting for repeated measures were used to estimate adjusted mean annualized changes in outcomes per quartile category of protein.

SETTING

Framingham Heart Study Offspring cohort, USA.

SUBJECTS

Participants (n 3066) with 12 333 unique observations, baseline (mean (sd)) age=54·0 (9·7) years, BMI=27·4 (4·9) kg/m2, 53·5 % female.

RESULTS

In fully adjusted models, there were favourable associations (mean (se)) of total protein with annualized changes in SBP (lowest v. highest intake: 0·34 (0·06) v. 0·04 (0·06) mmHg, P trend=0·001) and eGFR (-1·03 (0·06) v. -0·87 (0·05) ml/min per 1·73 m2, P trend=0·046), unfavourable associations with changes in FG (0·013 (0·004) v. 0·028 (0·004) mmol/l, P trend=0·004) and no associations with weight, WC, DBP or lipids. Animal protein was favourably associated with SBP and unfavourably with FG and WC; plant protein was favourably associated with FG and WC.

CONCLUSIONS

The present study provides evidence that protein intake may influence changes in cardiometabolic health independent of change in weight in healthy adults and that protein's role in cardiometabolic health may depend on the protein source.

Fatty Acid Composition of Adipose Tissue Triglycerides in Obese Diabetic Women After Bariatric Surgery: a 2-Year Follow up

Bariatric surgery is the most effective method in the treatment of obesity and type 2 diabetes (T2DM). The aim of this study was to evaluate the effects of different types of bariatric procedures on remission of T2DM and on the fatty acid composition in subcutaneous adipose tissue. Patients included obese diabetic women who underwent bariatric surgery: biliopancreatic diversion (BPD), n=8, laparoscopic gastric banding (LAGB), n=9 or laparoscopic greater curvature plication (LGCP), n=12. Anthropometric characteristics and fatty acid composition of adipose tissue (FA AT) were analyzed before surgery, then 6 months and 2 years after surgery. FA AT was analyzed by gas chromatography. Diabetes remission was estimated. BPD was most efficient in inducing a remission of diabetes (p=0.004). Significantly higher increases in lauric (12:0), myristoleic (14:1n-5) and palmitoleic (16:1n-7) acids and delta-9 desaturase were found two years after BPD, suggesting higher lipogenesis in adipose tissue. Docosatetraenoic acid (22:4n-6) increased significantly after BPD, while docosapentaenoic acid (22:5n-3) decreased 6 months after BPD and increased after 2 years. No changes were found after LAGB and LGCP after 2 years. Bariatric surgery led to significant changes in the fatty acid composition of subcutaneous adipose tissue in severely obese diabetic women after six months and two years, and was partly influenced by the type of surgery used.