Meta-analysis links dietary branched-chain amino acids to metabolic health in rodents

Background The role of dietary branched chain amino acids (BCAAs) and their effect on metabolic health is complex. How dietary BCAA levels and their interaction with background nutrition affect health is unclear. Here, we used meta-analysis and meta-regression, together with the nutritional modelling, to analyse the results of rodent studies that increased the level of dietary BCAAs and measured circulating levels, outcomes related to metabolic health, body mass and food intake. Results Across all studies, increasing dietary BCAAs resulted in increased levels of circulating BCAAs. These effects, however, were heavily moderated by background dietary levels whereby on high BCAA diets, further increases were not reflected in the blood. Impaired glucose tolerance was associated with elevated dietary BCAAs, with the greatest effect occurring with a simultaneous increase in total protein intake. Effects of dietary BCAAs on plasma glucose, insulin, or HOMA emerged only when dietary macronutrient background was considered. We found that elevated dietary BCAAs increases % body fat, with largest increases in adiposity occurring when BCAAs are increased on a high protein, low carbohydrate dietary background. Finally, we found that increased dietary BCAAs were associated with increased food intake when the background diet was low in BCAAs. Conclusion Our data highlights the interaction between BCAAs and background nutrition. We show that the effects of BCAAs on metabolic health cannot be studied in isolation but must be considered as part of complex mixture of dietary components.

Higher Animal Protein Intake During the Second Trimester of Pregnancy Is Associated With Risk of GDM

Background and Aims: This study aimed to examine the associations between the total protein intake as well as types and sources of proteins with the gestational diabetes mellitus (GDM) risk.Method and Results: This was a prospective cohort study of the pregnant women in Malaysia. In this study, the total, animal, and plant protein intakes were assessed using a semi-quantitative food frequency questionnaire. Of the 452 women, 48 (10.62%) were diagnosed with GDM. From pre-pregnancy to second trimester, most of the women had 10–20% of energy intake from protein (88.9–90.3%) and ≥75% of recommended protein intake (74.6–86.5%). The women in the highest tertile (T3) of total animal protein intake [adjusted odds ratio (AOR) = 2.76, 95% CI = 1.27–6.04] and red meat protein (AOR = 2.69, 95% CI = 1.27–5.70), specifically in the second trimester, had significantly higher GDM risk compared with the women in the middle tertile of intake (T2). Interestingly, the women in the T3 of egg protein in the second trimester were significantly at lower GDM risk (AOR = 0.43, 95% CI = 0.18–0.91) compared with those in T2.Conclusion: The highest tertile of animal protein (≥42.15 g/day) intake, particularly red meat protein in the second trimester was positively associated with the GDM risk, whereas the highest tertile of egg protein was inversely associated with the GDM risk. Protein intake before or during early pregnancy was not associated with the GDM risk. These findings underscore the importance of sources and types of protein intake, particularly after the first trimester of pregnancy, in relation to GDM risk.

The long-term association of different dietary protein sources with metabolic syndrome

Due to scarce epidemiologic data linking dietary protein intakes and metabolic syndrome (MetS), we aim to determine the longitudinal association of different types of dietary protein with the incidence of MetS among Iranians adults. The study was conducted in the framework of the Isfahan Cohort Study (ICS) on 6504 adults, aged ≥ 35 years, and free of MetS at baseline. A validated food frequency questionnaire was used for assessing usual dietary intakes. MetS was defined according to the Joint Scientific Statement. Mixed-effects logistic regression was applied to examine the associations between changes in weekly frequency consumption of protein and MetS status. After a median follow-up of 11.25 years, in multivariate-adjusted model, each additional frequency consumption of total protein intake (OR 0.83; 95% CI 0.81–0.85), animal protein (OR 0.80; 95% CI 0.77–0.83), plant protein (OR 0.70; 95% CI 0.64–0.76), red meat (OR 0.74; 95% CI 0.70–0.78), poultry (OR 0.73; 95% CI 0.68–0.78), egg (OR 0.79; 95% CI 0.72–0.88) and nuts and seeds (OR 0.77; 95% CI 0.71–0.84) was associated with reduced risk of MetS. No significant association was found for processed meat (OR 0.96; 95% CI 0.87–1.01) and legumes and soy (OR 0.96; 95% CI 0.86–1.07) with MetS. Our results suggest an independent inverse association between total protein, animal and plant protein and the risk of MetS. These associations did not differ by sex. Although our results can be considered to be a strategy to reduce MetS risk by dietary guidelines, randomized clinical trials are required to confirm our findings.

Physical Growth of Patients with Hereditary Tyrosinaemia Type I: A Single-Centre Retrospective Study

In a retrospective review, we aimed to assess long-term growth in 17 patients (n = 11 males) with hereditary tyrosinaemia type I (HTI). Median age at assessment was 15.6 years (5.7–26.6 years) and median age at diagnosis was 1 month (range: 0–16 months), with 35% (n = 6/17) symptomatic on presentation. From the age of 8 years, there was a noticeable change in median height, weight, and body-mass-index [BMI]-z-scores. Median height-for-age z-scores were consistently ≤ −1 (IQR −1.6, −0.5) during the first 8 years of life but increased with age. Weight-for-age z-scores ranged between −1 to 0 (IQR −1.2, 0.1) in the first 8 years; then increased to > 0.5 (IQR −0.3, 1.3) by age 16 years, and BMI-for-age z-scores ranged from 0 to 1 (IQR −0.7, 1.3) up to 8 years, and >1 (IQR −0.2, 1.9) until 16 years. The percentage of overweight and obesity was lowest in children aged < 5 years, and consistently > 40% in patients aged between 7 to 16 years. The prescribed total protein intake was associated with improved height growth (p < 0.01). Impaired growth in early life improved with age achieving normal population standards. Further studies are needed to investigate factors that influence growth outcome in HTI patients.

Association of Daily Physical Activity and Sedentary Behaviour with Protein Intake Patterns in Older Adults: A Multi-Study Analysis across Five Countries

Physical activity and protein intake are associated with ageing-related outcomes, including loss of muscle strength and functional decline, so may contribute to strategies to improve healthy ageing. We investigated the cross-sectional associations between physical activity or sedentary behaviour and protein intake patterns in community-dwelling older adults across five countries. Self-reported physical activity and dietary intake data were obtained from two cohort studies (Newcastle 85+ Study, UK; LiLACS, New Zealand Māori and Non-Māori) and three national food consumption surveys (DNFCS, The Netherlands; FINDIET, Finland; INRAN-SCAI, Italy). Associations between physical activity and total protein intake, number of eating occasions providing protein, number of meals with specified protein thresholds, and protein intake distribution over the day (calculated as a coefficient of variance) were assessed by regression and repeated measures ANOVA models adjusting for covariates. Greater physical activity was associated with higher total protein intake and more eating occasions containing protein, although associations were mostly explained by higher energy intake. Comparable associations were observed for sedentary behaviour in older adults in Italy. Evidence for older people with higher physical activity or less sedentary behaviour achieving more meals with specified protein levels was mixed across the five countries. A skewed protein distribution was observed, with most protein consumed at midday and evening meals without significant differences between physical activity or sedentary behaviour levels. Findings from this multi-study analysis indicate there is little evidence that total protein and protein intake patterns, irrespective of energy intake, differ by physical activity or sedentary behaviour levels in older adults.

No changes in dietary intake after quitting smoking; a prospective study in Switzerland

Background After quitting smoking, quitters frequently increase their weight and change their dietary intake. Still, most studies on the topic are over 20 years old and focused on few dietary markers. We analysed the changes in weight and dietary intake after quitting smoking using a large panel of dietary markers. Methods Prospective study including 5064 participants, 169 of whom (3.3%) quitted during a median follow-up of 5 years. Dietary intake was assessed using a food frequency questionnaire. Participants were excluded if they lacked dietary data or reported extreme total energy intakes (TEI) < 850 or > 4000 kcal/day. Results Data from 128 participants (43.8% women, aged 56.0 ± 10.0 years) were used. After quitting smoking, mean weight increased 2.1 ± 0.7 kg; the majority (58%) of the participants gained over 1 kg, and only 7.1% were on a diet to reduce their weight. Total protein intake increased from (median [interquartile range]) 14.4 [12.9–16.4] to 15.1 [13.4–17.9] % of total energy intake (TEI), p = 0.008, while animal protein intake increased from 9.7 [8.0–12.1] to 10.8 [8.5–13.5] %TEI, p = 0.011. Fish intake increased from 27 [17–45] to 37 [19–55] g/day, p = 0.016 and dairy intake decreased from 177 [94–288] to 150 [77–243] g/day, p = 0.009. No other changes were found. Among the 68 (53%) participants who reported time since quitting, quitting for <=1 year led to a decreased consumption of fruits, while the opposite was found for participants who quit for longer than one year. No associations were found between weight or dietary changes and time since quitting. Conclusions People who quit smoking tend to gain weight, do not significantly change their dietary intake, and seem to make little effort to prevent weight gain. Systematic dietary support should be provided to all smokers wishing to quit.

Protein Intake, IGF-1 Concentrations, and Growth in the Second Year of Life in Children Receiving Growing Up Milk – Lite (GUMLi) or Cow's Milk (CM) Intervention

The relationship of protein intake with insulin-like growth factor 1 (IGF-1) concentrations in well-nourished children during the second year of life is poorly understood. The aim of this study was to explore the effect of a reduced-protein Growing Up Milk Lite (GUMLi) or unfortified cow's milk (CM) on protein intake, growth, and plasma IGF-1 at 2 y. An exploratory analysis of a sub-sample of Auckland-based children (n = 79) in the GUMLi trial (a double-blind, randomised control trial, N = 160) completed in Auckland and Brisbane (2015–2017) was conducted. One-year old children were randomised to receive a reduced-protein GUMLi (1.7 g protein/100 mL) or a non-fortified CM (3.1 g protein/100 mL) for 12 months. Blood sampling and anthropometric measurements were made at 1 and 2 y. Diet was assessed using a validated food frequency questionnaire. Total protein intake (g/d) from all cow's milk sources was 4.6 g (95% CI: −6.7, −2.4; p &lt; 0.005) lower in the GUMLi group after 12 months of the intervention, with a significant group-by-time interaction (p = 0.005). Length-for-age (LAZ) and weight-for-length (WLZ) z-scores did not differ between groups, however, mean body fat % (BF%) was 3.2% (95%CI: −6.2, −0.3; p = 0.032) lower in the GUMLi group at 2 y. There was no difference between the intervention groups in relation to IGF-1 and IGF-BP3 (p = 0.894 and 0.698, respectively), with no group-by-sex interaction. After combining the groups, IGF-1 concentration at 2 y was positively correlated with parameters of growth (all p &lt; 0.05), total cow's milk intake (p = 0.032) after adjusting for sex, breastfeeding status, and gestation. Randomisation to a reduced protein GUMLi resulted in small reduction in %BF and lower total protein intakes but had no effect on growth. Plasma IGF-1 concentrations were independently associated with total protein intake from cow's milk at 2 y, highlighting a potential area of the diet to target when designing future protein-related nutrition interventions.Clinical Trial Registration: Australian New Zealand Clinical Trials Registry number: ACTRN12614000918628. Date registered: 27/08/2014.

The Association of Protein Intake and Bone Outcomes in Midwestern Post-menopausal Women

Objectives Determine the extent to which baseline protein and amino acid intake is independently associated with measures of baseline bone outcomes in a cohort of post-menopausal women. Methods This study was a secondary analysis of participants in the Heartland Osteoporosis Prevention Study (HOPS) randomized controlled trial evaluating the effect of different osteoporosis interventions on post-menopausal women in the Midwest. Diets were evaluated via a Harvard Willett Semi-quantitative Food Frequency Questionnaire (FFQ) at baseline. Dual energy x-ray absorptiometry (DXA) scans were used to collect bone mineral density (BMD) and trabecular bone score (TBS) measurements. Single and multivariate linear regression of total protein intake (g/d and g/kg/d), proline (g), and lysine (g) with BMD and TBS locations were conducted. Student T-tests were used to compare the bone outcome differences between groups with protein intake above and below 1.2g/kg. Results There were 249 participants available for analysis. Mean total protein intake was 82.7 g with 62% consuming &lt; 1.2/kg/d. After adjustment, for every additional gram intake of protein, lysine and proline, Hip BMD increased (Protein: β = 0.0005, P = 0.047; Lysine: β = 0.006, P = 0.04; Proline: β = 0.008, P = 0.04). Whole body BMD and TBS-1 were significantly associated with proline intake (Whole body BMD: β = 0.008, P = 0.04; TBS-1: β = −0.007, P = 0.02). After adjustment, women who consumed protein above 1.2 g/kg, had a Hip BMD 0.03 g/cm2 higher than those who consume protein below 1.2 g/kg (β = 0.03, P = 0.046). Lumbar BMD, Total L1-L4 BMD, TBS-2, TBS-3, TBS-4, and Total TBS were not significantly associated with protein or amino acid intakes after adjustment of covariates. Conclusions Higher protein intakes were associated with higher Hip BMD. Proline may play a controversial role in bone outcomes. Future research should investigate the role of dietary factors on BMD vs TBS. Funding Sources The original research was funded by the National Institute of Nursing Research of the National Institutes of Health under award number R01NR015029. No additional funding was used for the secondary analysis.

Estimated Protein Intake From Animal and Plant Foods by U.S. Adults, What We Eat in America, NHANES, 2015–2016

Objectives The 2020–2025 Dietary Guidelines for Americans encourage varying protein intake to include both animal foods and plant foods for the range of nutrients provided. The objective of this study is to estimate proportions of adults’ protein intake from animal and plant sources and the contribution of foods to each. Methods One day dietary intake data of adults 20+ years (N = 5017) in What We Eat in America (WWEIA), NHANES 2015–2016 were used. Proportions of protein intake from animal and plant sources were estimated from the ingredients for the foods in the Food and Nutrient Database for Dietary Studies (FNDDS) 2015–2016. Single ingredient foods such as chicken or beans were classified as 100% animal or plant, respectively. Proportions from multi-ingredient foods were determined from the amounts of animal and plant food ingredients in each item. If ingredients were not specified, the proportions from a similar food were applied. The proportions were applied to the dietary intakes to determine the population intake of protein from animal and plant sources. The WWEIA food categories were used to describe contribution of foods to animal and plant protein intake. Results Animal and plant foods accounted for 67% and 33% of total protein intake, respectively. Excluding mixed dishes, animal protein intake was contributed by dairy products (14%); meats (12%); poultry (16%); seafood (6%); cured meats (8%); and eggs (6%). Mixed dishes contributed 31% of animal protein intake. Protein from plant foods, excluding mixed dishes, was contributed by grains (24%); plant-based protein foods including legumes (4%), nuts and seeds (7%) soy products (1%); vegetables (9%); and fruit (2%). Mixed dishes accounted for 30% of plant protein intake; snacks and sweets contributed 14%. Conclusions Although protein intake from animal sources is relatively diverse, encouraging greater variety of protein intake from plant-based protein foods appears warranted. Funding Sources ARS-USDA.

Habitual intake of dietary L-arginine in relation to risk of type 2 diabetes: a prospective study

Background There are insufficient data in case of the potential association of habitual dietary L-arginine and the risk of type 2 diabetes mellitus (T2DM) incidence. Here we aimed to examine the potential effect of dietary L-arginine on the T2DM incidence. Methods For this cohort study, 2139 T2DM-free adults from the participations of Tehran Lipid and Glucose Study (TLGS) were recruited. Follow up period was approximately 5.8 years. Daily intakes of protein and L-arginine were estimated using a validated food frequency questionnaire with 168 food item. Hazard Ratios (HRs) and 95% confidence intervals (CIs), adjusted for sex, age, smoking, diabetes risk score, physical activity levels, and total energy intakes as well as carbohydrate, fiber, fats and lysine, were calculated for L-arginine as both absolute intake and its ratio from total protein. Results Mean (±SD) age of the participants was 38.9 (±12.6) years and 54.6% were women. Mean (±SD) intake of dietary protein and L-arginine was 77.2 (±22.4) and 4.05 (±1.50) g/d, respectively. An increased risk of T2DM (HR = 2.71, 95% CI = 1.20–6.09) was observed among participants with higher intakes of L-arginine (median intake of > 5.4 vs. 2.69 g/d). Total protein intake and the ratio of L-arginine to total protein intakes were not related to incidence of T2DM in both crude and adjusted models. Conclusion We found that higher dietary L-arginine levels may increase risk of T2DM and it may have an independent role in T2DM development.