The Association between Dietary Protein Intake and Sources and the Rate of Longitudinal Changes in Brain Structure.

Few studies have examined dietary protein intake and sources, in combination with longitudinal changes in brain structure markers. Our study aimed to examine the association between dietary protein intake and different sources of dietary protein, with the longitudinal rate of change in brain structural markers. A total of 2723 and 2679 participants from the UK Biobank were separately included in the analysis. The relative and absolute amounts of dietary protein intake were calculated using a 24 h dietary recall questionnaire. The longitudinal change rates of brain structural biomarkers were computed using two waves of brain imaging data. The average interval between the assessments was three years. We utilized multiple linear regression to examine the association between dietary protein and different sources and the longitudinal changes in brain structural biomarkers. Restrictive cubic splines were used to explore nonlinear relationships, and stratified and sensitivity analyses were conducted. Increasing the proportion of animal protein in dietary protein intake was associated with a slower reduction in the total hippocampus volume (THV, ß: 0.02524, p < 0.05), left hippocampus volume (LHV, ß: 0.02435, p < 0.01) and right hippocampus volume (RHV, ß: 0.02544, p < 0.05). A higher intake of animal protein relative to plant protein was linked to a lower atrophy rate in the THV (ß: 0.01249, p < 0.05) and LHV (ß: 0.01173, p < 0.05) and RHV (ß: 0.01193, p < 0.05). Individuals with a higher intake of seafood exhibited a higher longitudinal rate of change in the HV compared to those that did not consume seafood (THV, ß: 0.004514; p < 0.05; RHV, ß: 0.005527, p < 0.05). In the subgroup and sensitivity analyses, there were no significant alterations. A moderate increase in an individual's intake and the proportion of animal protein in their diet, especially from seafood, is associated with a lower atrophy rate in the hippocampus volume.

Effect of a plant protein-rich diet on postprandial phosphate metabolism in healthy adult men: a randomised controlled trial.

BACKGROUND: This study examined the effects of animal protein- and plant protein-rich diets on postprandial phosphorus metabolism in healthy male subjects. METHODS: The study was conducted by randomised parallel-group comparison of healthy men aged 21-24 years. In Study 1, participants were divided into two groups and consumed either a 70% animal protein diet (AD, n = 6) or a 70% plant protein diet (PD, n = 6). In Study 2, participants were divided into three groups and consumed either AD (n = 10), PD (n = 10) or AD + DF, a 70% animal protein diet loaded with the same amount of fibre as PD (n = 9). The phosphorus contents of the diets used in this study were nearly equivalent (AD, 710.1 mg; PD, 709.7 mg; AD + DF, 708.9 mg). Blood and urine samples were collected before, and 2 and 4 h after the meal to measure phosphorus and calcium levels. RESULTS: In Study 1, PD consumption resulted in lower blood and urinary phosphorus concentrations 2 h postprandially compared with AD (p < 0.05). In Study 2, blood phosphorus levels in AD + DF after the diet remained lower, but not significantly so compared with AD, and urinary phosphorus levels were significantly lower 2 h postprandially (p < 0.05). CONCLUSIONS: A plant protein-rich diet reduced rapid postprandial increases in blood and urinary phosphorus concentrations compared with the animal protein-rich diets, suggesting that dietary fibre may play a partial role in the postprandial decreases in blood and urinary phosphorus concentrations.

Protein intake and its association with sleep quality: results from 3 prospective cohort studies.

BACKGROUND/OBJECTIVES: Sleep quality is a critical factor for daytime functioning and chronic disease risk. We investigated the association between intakes of total protein and protein subtypes and sleep quality in three U.S. cohorts. SUBJECTS/METHODS: In the Nurses' Health Study (NHS), NHS2, and Health Professionals Follow-up study (HPFS), dietary intake was assessed every 4 years using validated food frequency questionnaires. Sleep quality was measured once with the Pittsburgh Sleep Quality Index or adapted versions. With ordinal logistic regression, odds ratios (OR) and 95% confidence intervals (CI) were calculated to estimate the odds of having better sleep quality versus poorer sleep quality depending on protein intake (%Energy) based on the average of the prior two dietary questionnaires. RESULTS: In 32,212 women from NHS, 51,126 women from NHS2, and 14,796 men from HPFS, total protein intake was not associated with sleep quality. However, the intake of protein from vegetable sources showed no association or a positive association with sleep quality (OR for quartile 4 versus quartile 1 in NHS: 1.12, 1.04-1.20, P-trend < 0.001; NHS2: 1.01, 0.95-1.07, P-trend = 0.90; HPFS: 1.11, 0.99-1.23, P-trend = 0.05), whereas divergent results were observed for animal protein sources. Overall, intakes of processed red meat and poultry were associated with worse sleep quality, whereas no or positive associations were observed for dairy and fish protein. CONCLUSION: Our results suggest that plants as a source of protein may be associated with better sleep quality than animal sources of protein. Further studies are warranted to validate our findings.

Dietary intake of plant- and animal-derived protein and incident cardiovascular diseases: the pan-European EPIC-CVD case-cohort study.

BACKGROUND: Epidemiological evidence suggests that a potential association between dietary protein intake and cardiovascular disease (CVD) may depend on the protein source, that is, plant- or animal-derived, but past research was limited and inconclusive. OBJECTIVES: To evaluate the association of dietary plant- or animal-derived protein consumption with risk of CVD, and its components ischemic heart disease (IHD) and stroke. METHODS: This analysis in the European Prospective Investigation into Cancer and Nutrition (EPIC)-CVD case-cohort study included 16,244 incident CVD cases (10,784 IHD and 6423 stroke cases) and 15,141 subcohort members from 7 European countries. We investigated the association of estimated dietary protein intake with CVD, IHD, and stroke (total, fatal, and nonfatal) using multivariable-adjusted Prentice-weighted Cox regression. We estimated isocaloric substitutions of replacing fats and carbohydrates with plant- or animal-derived protein and replacing food-specific animal protein with plant protein. Multiplicative interactions between dietary protein and prespecified variables were tested. RESULTS: Neither plant- nor animal-derived protein intake was associated with incident CVD, IHD, or stroke in adjusted analyses without or with macronutrient-specified substitution analyses. Higher plant-derived protein intake was associated with 22% lower total stroke incidence among never smokers [HR 0.78, 95% confidence intervals (CI): 0.62, 0.99], but not among current smokers (HR 1.08, 95% CI: 0.83, 1.40, P-interaction = 0.004). Moreover, higher plant-derived protein (per 3% total energy) when replacing red meat protein (HR 0.52, 95% CI: 0.31, 0.88), processed meat protein (HR 0.39, 95% CI: 0.17, 0.90), and dairy protein (HR 0.54, 95% CI: 0.30, 0.98) was associated with lower incidence of fatal stroke. CONCLUSION: Plant- or animal-derived protein intake was not associated with overall CVD. However, the association of plant-derived protein consumption with lower total stroke incidence among nonsmokers, and with lower incidence of fatal stroke highlights the importance of investigating CVD subtypes and potential interactions. These observations warrant further investigation in diverse populations with varying macronutrient intakes and dietary patterns.

Association between protein intake and risk of gestational diabetes mellitus: A systematic review and dose-response meta-analysis of cohort studies.

BACKGROUND: Gestational diabetes mellitus (GDM) is a common condition in pregnancy, the prevalence of which has increased. Identifying modifiable risk factors for GDM, such as dietary factors, could prevent or delay the onset of the condition. Our goal was to perform a comprehensive meta-analysis of cohort studies, to summarize the current evidence on the relationship between total, animal, and plant protein intake during pregnancy, as well as pre-pregnancy protein intake, and the risk of GDM. METHODS: A literature search was completed using Scopus, PubMed, Web of Science, and Google Scholar up to January 2023 and references of retrieved relevant articles. Observational studies examining the association between the consumption of dietary protein from different sources in pre-pregnancy or/and during pregnancy and the risk of GDM were included. To combine effect sizes for the comparison between the highest and lowest categories of protein intake, a random effects model was utilized. Dose-response relationships were investigated using a 1-stage random-effects model. RESULTS: 8 observational studies were included in the systematic review and 5 prospective cohort studies in the meta-analysis, involving a total of 24,160 participants and 2450 cases of GDM. The analysis revealed a significant association between total protein intake during pregnancy and an elevated risk of GDM (relative risk (RR): 2.24, 95 % confidence interval (CI): 1.67-3.00, P = 0.000). Conversely, no significant association was found between total protein intake before pregnancy and the risk of GDM. Both animal protein intake before pregnancy (RR: 1.47, 95 % CI: 1.06-2.03, P = 0.021) and during pregnancy (RR; 2.31, 95 % CI: 1.43-3.73, P = 0.001) showed a significant association with GDM. Interestingly, there was no significant association between the consumption of plant protein both before and during pregnancy and the risk of GDM. Further analysis revealed that an additional 5 % energy from total protein and animal protein per day was associated with a 24 % and 32 % before and 114 % and 67 % increased risk of GDM during pregnancy respectively. CONCLUSION: In conclusion, consumption of animal protein and total protein before pregnancy is associated with an increased risk of GDM, although the association is not significant for total protein. Conversely, plant protein intake is linked to a decreased risk of GDM, however, the results are not significant. The intake of any protein type (plant/animal/total) during pregnancy is associated with an elevated risk of GDM, with this association being statistically insignificant for plant protein. Further cohort studies are required to validate the findings presented in this study. REGISTRATION: PROSPERO (CRD42023396215).

Association of dietary protein intake, inflammation with muscle mass, physical performance and incident sarcopenia in Chinese community-dwelling older adults.

OBJECTIVES: Inflammation and impaired muscle synthesis are important factors of sarcopenia. Plant protein may reduce inflammation but may not be as efficient as animal protein in providing essential amino acids. We therefore examined the associations between dietary protein intake and changes in muscle mass and physical performance, incident sarcopenia, and the interaction effect of inflammation. DESIGN: Prospective cohort study. SETTING: The Mr. OS and Ms. OS (Hong Kong) cohort. PARTICIPANTS: A total of 2,811 sarcopenia-free participants and 569 sarcopenia participants aged ≥65 years were recruited from communities. MEASUREMENTS: Dietary protein intake was assessed using a validated food frequency questionnaire. Serum high-sensitivity C-reactive protein (hs-CRP) was measured. Linear regression examined the associations between dietary protein intake and 4-year changes in muscle mass and physical performance. Cox regression examined the association between dietary protein intake and incident sarcopenia. RESULTS: Higher plant protein intake, but not total and animal protein, was associated with less decline in muscle mass and gait speed among sarcopenia-free participants. Conversely, higher ratio of animal-to-plant protein was associated with reduced muscle mass loss among participants with sarcopenia. The highest tertile of plant protein intake was associated with lower incident sarcopenia risk (HR: 0.75, 95% CI: 0.57-0.98; P-trend = 0.034) compared to the lowest tertile. Notably, this association was observed among participants with higher serum hs-CRP levels (HR: 0.57, 95% CI: 0.34-0.95), but not in those with lower hs-CRP levels. CONCLUSION: Dietary animal and plant protein intake have differential associations with muscle mass and physical performance in older adults with and without sarcopenia. The role of plant protein in preventing sarcopenia involves modulation of inflammation.

Association between total and animal proteins with risk of fracture: A systematic review and dose-response meta-analysis of cohort studies.

Previous cohort studies have indicated that consumption of total and animal proteins are related to fracture risk; however, results were inconclusive. This dose-dependent review sought to summarize the earlier evidence regarding the relation between total and animal proteins and fracture risk. We searched Scopus, PubMed, and Web of Science until July 2023 for original research articles examining the association of certain types of proteins and the incidence of all fractures in general adults. Summary relative risks (RRs) were calculated using random effects analysis to examine the relation between each certain amount (g/day) increment of total and animal protein and fracture risk. Twenty cohort studies with serious to moderate risk of bias involving 780,322 individuals were included. There was a non-statistically significant relation between intake of animal proteins and dairy products and all fracture risk. However, 43% and 5% decreased incidence of fracture was obtained with total protein (RR, 0.57; 95%CI, 0.36 to 0.93; per 100 g/day) and fish (RR, 0.95; 95%CI, 0.91 to 0.99; per 15 g/day) intake. Every 100 g/day total and animal protein consumption and every 15 g/day fish consumption were linked to 48%, 50%, and 5% lower hip fracture risk. Greater dietary animal protein intake might reduce risk of hip but not fracture at any site. We obtained a lower risk of any or hip fracture with greater total protein (per 100 g/day) and fish (per 15 g/day) intake. No evidence was obtained that higher intake of dairy could decrease risk of fracture.

Mental models of the protein shift: Exploring consumers' perceptions of the transition.

The protein transition is one of today's major societal challenges to mitigate climate change. To support lasting consumer engagement, it has been suggested to look into consumers' understanding of the protein transition to identify barriers that go beyond the practical issues of changing one's diet. The current study explored consumers' mental models of how the transition unfolds to examine which factors consumers perceive as important drivers of the transition. With a fixed set of factors and actors identified with a questionnaire, Dutch consumers (N = 214) mapped their mental models. The content and structure of the mental models were analyzed with a focus on how consumers perceive their own role. Animal well-being and environmental concerns were most often included as important drivers. The findings showed a lack of consensus about which actor(s) drive the transition (i.e., none of the actors were included by a majority of the participants). This diffusion of responsibility may be a barrier for consumers to act. Moreover, the relative simplicity of the observed mental models suggests that consumers do not yet employ systems thinking. A systems thinking mindset may help consumers understand how the system behind the transition works and how their individual contributions matter. Two avenues to encourage consumer engagement were identified: 1) emphasizing the responsibility of different actors and what consumers can contribute, and 2) encouraging a systems thinking mindset.

The role of dietary plant and animal protein intakes on mitigating sarcopenia risk.

PURPOSE OF REVIEW: To highlight contemporary findings comparing the digestibility of animal and plant proteins, their stimulatory effects on muscle protein synthesis, and associations with sarcopenia. RECENT FINDINGS: Animal proteins are more digestible than plant proteins, resulting in greater amino acid availability and stimulation of muscle protein synthesis. However, isolated plant proteins, plant protein blends, and modified plant proteins enriched with indispensable amino acids can elicit comparable digestion and absorption kinetics to animal proteins. More research is needed to determine whether these modified plant protein sources can effectively mitigate sarcopenia risk. SUMMARY: Both animal and plant protein foods can be incorporated into a healthful eating plan that limits risk of age-related diseases, such as sarcopenia. Humans eat food rather than isolated nutrients; as such, considering the context of the overall diet and its impact on health, instead of solely focusing on individual nutrients in isolation, is important.

In vitro digestion mimicking conditions in young and elderly reveals marked differences between profiles and potential bioactivity of peptides from meat and soy proteins.

We applied in vitro models of gastrointestinal (GI) digestion simulating the conditions of the GI tract of healthy adults and elderly individuals with achlorhydria (EA) to investigate differences in the digestibility of meat (chicken, beef and pork) and soy proteins. Digestibility was significantly affected by EA alterations. Peptidomics analyses revealed significant differences in peptide profiles between control and EA conditions, including number, length distribution, clustering, and differentially abundant peptides (DAPs). Our results revealed that the differences in meat peptide profiles diminished going from the gastric to intestinal phase. For soy protein, the marked differences between control and EA conditions were maintained in the gastric and intestinal phases. Higher numbers of potentially bioactive peptides were generated under the control condition compared to the EA condition. The present study provides insight into the distinct peptide profiles generated by in vitro digestion of meat and soy proteins under adult and EA GI conditions.

Association of animal and plant protein intakes with biomarkers of insulin and insulin-like growth factor axis.

BACKGROUND & AIMS: Insulin and insulin-like growth factor (IGF)-1 signaling is a proposed mechanism linking dietary protein and major chronic diseases. However, it is unclear whether animal and plant proteins are associated with biomarkers of insulin and IGF axis. METHODS: We analyzed a total of 14,709 participants from Nurses' Health Study and Health Professionals Follow-up Study who had provided a blood sample. Detailed dietary information was assessed using validated food frequency questionnaires. We assessed C-peptide, insulin, IGF-1, and IGF binding proteins (BP). Multivariable-adjusted linear regressions were used to examine associations of animal and plant protein intake with biomarkers after adjusting for confounders. RESULTS: The medians (5th-95th percentiles) of animal and plant protein intake (% of total energy) were 13% (8-19%) and 5% (4-7%), respectively. Compared to participants in the lowest quintile, those in the highest quintile of animal protein had 4.8% (95% CI: 1.9, 7.9; P-trend<0.001) higher concentration of IGF-1 and -7.2% (95% CI: -14.8, 1.1; P for trend = 0.03) and -11.8% (95% CI: -20.6, -1.9; P-trend<0.001) lower concentration of IGFBP-1 and IGFBP-2, respectively, after adjustment for major lifestyle factors and diet quality. In contrast, no association was observed between animal protein intake and C-peptide, insulin and IGFBP-3. The associations were restricted to participants with at least one unhealthy lifestyle risk factor (i.e., overweight/obese, physical inactivity, smoking, and heavy alcohol intake). Plant protein tended to be strongly associated with numerous biomarkers in age-adjusted analyses but these became largely attenuated or non-significant in multivariable adjustment. Plant protein intake remained positively associated with IGF-1 (P-trend = 0.002) and possibly IGFBP-1 (P-trend = 0.02) after multivariable adjustment. Substitution of plant protein with animal protein sources was associated with lower IGFBP-1. In additional analysis, IGF-1 and IGFBPs were estimated to mediate approximately 5-20% of the association between animal protein and type 2 diabetes. CONCLUSIONS: Higher animal protein intake was associated with higher IGF-1 and lower IGFBP-1 and IGFBP-2, whereas higher plant protein intake was associated with higher IGF-1 and IGFBP-1.

Associations of Total Protein or Animal Protein Intake and Animal Protein Sources with Risk of Kidney Stones: A Systematic Review and Dose-Response Meta-Analysis.

We conducted the present systematic review and meta-analysis to evaluate the association of total protein, animal protein, and animal protein sources with risk of kidney stones in the general population. A literature search was performed in PubMed/Medline, Scopus, and EMBASE up to July 2021. We assessed the credibility of evidence based on NutriGrade scoring system. A total of 14 prospective cohort studies were included. A positive association was observed between higher intake of nondairy animal protein (RR: 1.11; 95% CI: 1.03, 1.20; I2 = 0%, n = 4), total meat and meat products (RR: 1.22; 95% CI: 1.09, 1.38; I2 = 13%, n = 3), and processed meat (RR: 1.29; 95% CI: 1.10, 1.51; I2 = 0%, n = 2) with risk of kidney stones. There was an inverse association between higher intake of dairy protein and risk of kidney stones (RR: 0.91; 95% CI: 0.84, 0.99; I2 = 0%, n = 4). Moreover, each 100-gincrement of red meat intake was significantly associated with increased risk of kidney stones (RR: 1.39; 95% CI: 1.13, 1.71). According to the NutriGrade scoring system, the credibility of evidence for most of the exposures was rated as low. We found some kind of publication bias in the association of animal protein intake and risk of kidney stones, according to Egger's and Begg's tests. In the sensitivity analysis of processed meat as well as dairy consumption with risk of kidney stones we observed in each individual analysis, 1 study changed the overall estimate. Further observational studies are needed to confirm the present results. The protocol of the present study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42021230125: https://www.crd.york.ac.uk/PROSPERO).

Association between dietary acid load and clinical features of migraine headaches among Iranian individuals.

There is limited evidence regarding the possible role of dietary acid load (DAL) in the pathophysiology of migraine headaches. Therefore, we sought to examine DAL in relation to the clinical features of migraine including headache frequency, severity and duration, headache impact test-6 (HIT-6), and serum levels of nitric oxide (NO). In the present cross-sectional study, 262 patients (38 men and 224 women aged 20-50 years) were recruited through a simple random sampling method. Dietary intakes were obtained by using a validated 168-item semi-quantitative food frequency questionnaire (FFQ). DAL was then calculated by two different methods; potential renal acid load (PRAL) and net endogenous acid production (NEAP). In total, 262 patients with a mean (SE) age of 36.1 (0.53) and a BMI of 25.55 (0.21) were included in the current study. After controlling for potential confounders, a higher DAL was positively associated with headache frequency in those with the highest DAL score compared to the lowest (PRAL; ß = 2.33; 95% CI 0.78, 3.88; NEAP; ß = 1.74; 95% CI 0.13, 3.34). Increasing NEAP from 28.96 to 35.89 resulted in a 3.43 and 2.74 increment in HIT-6 scores in the crude (95% CI 1.35, 5.52) and fully-adjusted models (95% CI 0.40, 5.07), respectively. Moreover, a higher dietary PRAL was significantly associated with migraine-related disability, as shown by HIT-6, in subjects of the third tertile compared to those in the first tertile after controlling for confounders (ß = 2.42; 95% CI 0.13, 4.70). In conclusion, our study highlighted the importance of the acid-base properties of a diet in the pathophysiology of migraine headaches. However, further well-designed studies are needed to confirm our findings.

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.

An evaluation of the serum carbon isotope ratio as a candidate predictive biomarker of the dietary animal protein ratio (animal protein/total protein) in a 15-day controlled feeding study of US adults.

BACKGROUND: The serum natural abundance carbon isotope ratio (CIR) was recently identified as a candidate biomarker of animal protein intake in postmenopausal women. Such a biomarker would help clarify the relation between dietary protein source (plant or animal) and chronic disease risk. OBJECTIVES: We aimed to evaluate the performance of the serum CIR as a biomarker of dietary protein source in a controlled feeding study of men and women of diverse age and BMI. METHODS: We conducted a 15-d feeding study of 100 adults (age: 18-70 y, 55% women) in Phoenix, AZ. Participants were provided individualized diets that approximated habitual food intakes. Serum was collected at the end of the feeding period for biomarker measurements. RESULTS: Median [IQR] animal protein intake was 67 g/d [55-88 g/d], which was 64% of total protein. The serum CIR was positively correlated with animal protein and inversely correlated with plant protein intake, leading to a strong correlation (r2 = 0.76) with the dietary animal protein ratio (APR; animal/total protein). Regressing serum CIR on the APR, serum nitrogen isotope ratio (NIR), gender, age, and body weight generated an R2 of 0.78. Following the measurement error model for predictive biomarkers, the resulting regression equation was then inverted to develop a calibrated biomarker equation for APR. Added sugars ratio (added/total sugars intake) and corn intakes also influenced the serum CIR but to a much lesser degree than the APR; variations in these intakes had only small effects on biomarker-estimated APR. CONCLUSIONS: Based on our findings in this US cohort of mixed sex and age, we propose the serum CIR alongside NIR as a predictive dietary biomarker of the APR. We anticipate using this biomarker to generate calibrated estimates based on self-reported intake and ultimately to obtain more precise disease risk estimates according to dietary protein source.

Associations between dietary intake of total protein and sources of protein (plant vs. animal) and risk of all-cause and cause-specific mortality in older Australian men: The Concord Health and Ageing in Men Project.

BACKGROUND: The association between dietary protein intake and the risk of mortality is still controversial. The present study aimed to examine the associations between dietary total, animal and plant protein intake and all-cause and cause-specific mortality. METHODS: Community-dwelling men aged ≥ 70 years were recruited from local government areas surrounding Concord Hospital in Sydney, New South Wales for the Concord Health and Ageing in Men Project (CHAMP). The research dietitian administered a standardised validated diet history questionnaire to capture baseline dietary intake. In total, 794 men participated in a detailed diet history interview at the third wave. Adequacy of protein intake was assessed by comparing participant intake with the Nutrient Reference Values. Total protein intake was categorised into quintiles. Sources of protein were also captured. Mortality was ascertained through the New South Wales death registry. Cox proportional hazard models were used to assess the association between dietary total, animal and plant protein intake and risk of mortality. RESULTS: The mean age of the CHAMP men was 81 years. In total, 162 men died during a median follow-up of 3.7 years. Of these, 54 (33.3%) and 49 (30.2%) men died due to cancer and cardiovascular disease, respectively. There were U-shaped associations between protein intake and all-cause and cancer mortality. In multiple adjusted analysis, the second (hazard ratio [HR] = 0.38; 95% confidence interval [CI] = 0.18-0.82) and third (HR = 0.36; 95% CI = 0.16-0.82) quintiles of protein intakes were significantly associated with reduced risk of all-cause and only second quintile (HR = 0.47; 95% CI = 0.10-0.93) of protein intake was significantly associated with cancer mortality. Each serve increase in animal protein was significantly associated with 12% (HR = 1.12; 95% CI = 1.00-1.26) and 23% (HR = 1.23; 95% CI = 1.02-1.49) increased risk of all-cause mortality and cancer mortality respectively. Conversely, each serve increase in plant protein intake was significantly associated with 25% (HR = 0.75; 95% CI 0.61-0.92) and 28% (HR = 0.72; 95% CI = 0.53-0.97) reduced risk of all-cause and cancer mortality, respectively. No such associations were observed for cardiovascular disease mortality. CONCLUSIONS: Both second and third quintiles of total protein intake were associated with reduced all-cause and cancer mortality. Plant protein was inversely associated with all-cause and cancer mortality, whereas animal protein intake was positively associated with mortality.

The importance of protein sources to support muscle anabolism in cancer: An expert group opinion.

This opinion paper presents a short review of the potential impact of protein on muscle anabolism in cancer, which is associated with better patient outcomes. Protein source is a topic of interest for patients and clinicians, partly due to recent emphasis on the supposed non-beneficial effect of proteins; therefore, misconceptions involving animal-based (e.g., meat, fish, dairy) and plant-based (e.g., legumes) proteins in cancer are acknowledged and addressed. Although the optimal dietary amino acid composition to support muscle health in cancer is yet to be established, animal-based proteins have a composition that offers superior anabolic potential, compared to plant-derived proteins. Thus, animal-based foods should represent the majority (i.e., ≥65%) of protein intake during active cancer treatment. A diet rich in plant-derived proteins may support muscle anabolism in cancer, albeit requiring a larger quantity of protein to fulfill the optimal amino acid intake. We caution that translating dietary recommendations for cancer prevention to cancer treatment may be inadequate to support the pro-inflammatory and catabolic nature of the disease. We further caution against initiating an exclusively plant-based (i.e., vegan) diet upon a diagnosis of cancer, given the presence of elevated protein requirements and risk of inadequate protein intake to support muscle anabolism. Amino acid combination and the long-term sustainability of a dietary pattern void of animal-based foods requires careful and laborious management of protein intake for patients with cancer. Ultimately, a dietary amino acid composition that promotes muscle anabolism is optimally obtained through combination of animal- and plant-based protein sources.

Dietary Animal to Plant Protein Ratio Is Associated with Risk Factors of Metabolic Syndrome in Participants of the AHS-2 Calibration Study.

BACKGROUND: Few research studies have focused on the effects of dietary protein on metabolic syndrome and its components. Our objective was to determine the relationship between the type of dietary protein intake and animal to plant (AP) protein ratio with metabolic syndrome and its components. METHODS: This population-based study had a cross sectional design and conducted on 518 participants of the Adventist Health Study 2 (AHS-2) Calibration Study. Two sets of three dietary 24-h recalls were obtained six months apart. Anthropometric measures and biochemical tests were performed in clinics. Regression calibration models were used to determine the association of type of dietary protein with metabolic syndrome and its components (raised triglyceride, raised blood pressure, reduced high-density lipoprotein cholesterol (HDL), raised fasting blood glucose and increased waist circumference). RESULTS: The likelihood of metabolic syndrome was lower in those with higher total dietary protein and animal protein intake (p = 0.02).Total protein (ß = 0.004, [95%CI: 0.002, 0.007]), animal protein intake (ß = 0.004, [95%CI: 0.001, 0.007]) and AP protein intake ratio (ß = 0.034, [95%CI: 0.021, 0.047]) were positively associated with waist circumference. Higher AP protein ratio was related to higher fasting blood glucose (ß = 0.023, [95%CI: 0.005, 0.041]). CONCLUSION: Our study suggests that considering a significant amount of plant protein as a part of total dietary protein has beneficial effects on cardiometabolic risk factors.

Dairy protein intake is inversely related to development of non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is closely related to metabolic dysfunction, including insulin resistance, obesity, and metabolic syndrome. Dairy protein, rich in casein and whey protein, could help to reduce metabolic diseases. Therefore, we investigated the relationship between dairy protein intake and incident NAFLD. METHODS: We analyzed data for 5171 adults aged 40-69 years from the Korean Genome and Epidemiology Study.(KoGES) Participants were separated as men, women aged ≥50 years, and women aged <50 years and then divided into tertiles based on dairy protein intake. NAFLD was defined as NAFLD liver fat score >-0.640. Scores were calculated as 1.18 × metabolic syndrome (Yes: 1, No: 0) + 0.45 × diabetes mellitus (Yes: 2, No: 0) + 0.15 × serum insulin +0.04 × AST - 0.94 × (AST/ALT) - 2.89. Cox proportional hazards spline curves were drawn to visualize dose-response relationships between dairy protein intake and incident NAFLD. Multiple Cox hazard regression analysis was conducted to examine associations between dairy protein intake and incident NAFLD. RESULTS: The Cox proportional hazards spline curves revealed a negative linear relationship between dairy protein intake and incident NAFLD. The cumulative incidence of NAFLD significantly decreased with increasing tertiles of dairy protein intake in men and women aged ≥50 years. After adjusting for confounding factors, the hazard ratios and 95% confidence intervals for NAFLD in the middle and highest tertiles, compared to the lowest tertile, were 0.80 (0.67-0.96) and 0.71 (0.57-0.88) in men, 0.89 (0.72-1.09) and 0.72 (0.56-0.92) in women aged ≥50 years, and 1.01 (0.80-1.27) and 0.91 (0.67-1.24) in women aged <50 years, respectively. CONCLUSIONS: We found that higher dairy protein intake was significantly and inversely associated with the risk of incident NAFLD in men and women aged ≥50 years. Consumption of milk and other dairy products could help prevent the development of NAFLD.

Dietary patterns and risk of non-alcoholic fatty liver disease in adults: A prospective cohort study.

BACKGROUND AND AIMS: Prospective cohort studies linking dietary patterns and non-alcoholic fatty liver disease (NAFLD) are limited, especially in Asian populations. This study aimed to prospectively investigate the association between dietary patterns and risk of NAFLD in a general Chinese adult population. METHODS: This study included a total of 17,360 participants free from NAFLD at baseline. Dietary patterns at baseline were identified with factor analysis based on responses to a validated 100-item food frequency questionnaire. NAFLD was diagnosed by abdominal ultrasound after excluding other causes related to chronic liver disease. Cox proportional regression models were used to assess the association between dietary patterns and risk of NAFLD. RESULTS: During a median follow-up of 4.2 years, 4034 NAFLD cases were documented. Three main dietary patterns were extracted: sugar rich dietary pattern, vegetable rich dietary pattern, and animal food dietary pattern. After adjusting for age, sex, body mass index, smoking, alcohol, education, occupation, income, physical activity, total energy intake, personal and family history of disease, depressive symptoms, dietary supplement use, inflammation markers, and each other dietary pattern score, comparing the highest with the lowest quartiles of dietary pattern scores, the multivariable hazard ratios (95% confidence interval) of NAFLD were 1.11 (1.01, 1.23) for sugar rich dietary pattern, 0.96 (0.86, 1.07) for vegetable rich dietary pattern, and 1.22 (1.10, 1.36) for animal food dietary pattern. Further adjustment for waist circumference instead of body mass index provided similar results. CONCLUSION: Dietary patterns rich in animal foods or sugar were associated with a higher risk of NAFLD among Chinese adults, whereas a vegetable rich dietary pattern was not associated.