High intakes of protein and processed meat associate with increased incidence of type 2 diabetes

Association between total, animal, and plant protein intake and type 2 diabetes risk in adults: A systematic review and dose-response meta-analysis of prospective cohort studies

BACKGROUND AND AIMS

While clinical studies indicate that dietary protein may benefit glucose homeostasis in type 2 diabetes (T2D), the impact of dietary protein, including whether the protein is of animal or plant origin, on the risk of T2D is uncertain. We conducted a systematic review and meta-analysis to evaluate the associations of total, animal, and plant protein intakes with the risk of T2D.

METHODS

A systematic search was performed using multiple data sources, including PubMed/Medline, ISI Web of Science, Scopus, and Google Scholar, with the data cut-off in May 2023. Our selection criteria focused on prospective cohort studies that reported risk estimates for the association between protein intake and T2D risk. For data synthesis, we calculated summary relative risks and 95% confidence intervals for the highest versus lowest categories of protein intake using random-effects models. Furthermore, we conducted both linear and non-linear dose-response analyses to assess the dose-response associations between protein intake and T2D risk.

RESULTS

Sixteen prospective cohort studies, involving 615,125 participants and 52,342 T2D cases, were identified, of which eleven studies reported data on intake of both animal and plant protein. Intakes of total (pooled effect size: 1.14, 95% CI: 1.04-1.24) and animal (pooled effect size: 1.18, 95% CI: 1.09-1.27) protein were associated with an increased risk of T2D. These effects were dose-related - each 20-g increase in total or animal protein intake increased the risk of T2D by ∼3% and ∼7%, respectively. In contrast, there was no association between intake of plant protein and T2D risk (pooled effect size: 0.98, 95% CI: 0.89-1.08), while replacing animal with plant protein intake (per each 20 g) was associated with a reduced risk of T2D (pooled effect size: 0.80, 95% CI: 0.76-0.84).

CONCLUSIONS

Our findings indicate that long-term consumption of animal, but not plant, protein is associated with a significant and dose-dependent increase in the risk of T2D, with the implication that replacement of animal with plant protein intake may lower the risk of T2D.

Nutrient quality in dietary therapy for diabetes and diabetic kidney disease

Dietary therapy is crucial for diabetes care with the aim of preventing the onset and progression of diabetes and its complications. The traditional approach to dietary therapy for diabetes has primarily focused on restricting the intake of the three major nutrients and rigorously controlling blood glucose levels. However, advancements in nutritional science have shown that within the three major nutrients - carbohydrates, proteins and lipids - there exist multiple types, each with distinct impacts on type 2 diabetes and its complications, sometimes even showing conflicting effects. In light of this, the present review shifts its focus from the quantity to the quality of the three major nutrients. It aims to provide an overview of how the differences in nutrient quality can influence onset and progression of type 2 diabetes and diabetic kidney disease, highlighting the diverse effects and, at times, contradictory impacts associated with each nutrient type.

Impacts of dietary animal and plant protein on weight and glycemic control in health, obesity and type 2 diabetes: friend or foe?

It is well established that high-protein diets (i.e. ~25-30% of energy intake from protein) provide benefits for achieving weight loss, and subsequent weight maintenance, in individuals with obesity, and improve glycemic control in type 2 diabetes (T2D). These effects may be attributable to the superior satiating property of protein, at least in part, through stimulation of both gastrointestinal (GI) mechanisms by protein, involving GI hormone release and slowing of gastric emptying, as well as post-absorptive mechanisms facilitated by circulating amino acids. In contrast, there is evidence that the beneficial effects of greater protein intake on body weight and glycemia may only be sustained for 6-12 months. While both suboptimal dietary compliance and metabolic adaptation, as well as substantial limitations in the design of longer-term studies are all likely to contribute to this contradiction, the source of dietary protein (i.e. animal vs. plant) has received inappropriately little attention. This issue has been highlighted by outcomes of recent epidemiological studies indicating that long-term consumption of animal-based protein may have adverse effects in relation to the development of obesity and T2D, while plant-based protein showed either protective or neutral effects. This review examines information relating to the effects of dietary protein on appetite, energy intake and postprandial glycemia, and the relevant GI functions, as reported in acute, intermediate- and long-term studies in humans. We also evaluate knowledge relating to the relevance of the dietary protein source, specifically animal or plant, to the prevention, and management, of obesity and T2D.

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

The protective association of dairy intake and the adverse impact of iron on gestational diabetes risk

Background: Gestational diabetes (GDM) is a pregnancy-related glucose intolerance with significant implications for maternal and fetal health. Calcium is essential for insulin secretion and metabolism, while iron intake may also impact GDM. This case-control study was conducted to investigate the relationship between calcium and iron intake with the risk of GDM. Methods: GDM was defined as Fasting Blood Sugar>92mg/dL or 75g Oral-Glucose-Tolerance-Test 120-minutes>153mg/dL. A 168-Item food-frequency-questionnaire was used to collect dietary calcium and iron intake from 24-40 weeks of gestation. The impact of total iron, red, processed/unprocessed meat consumption, calcium, and dairy intake on GDM were investigated. Results: A total of 229 GDM and 205 non-GDM women (18-45 years) participated. GDM group had higher pre-pregnancy weight, weight gain, and pre-pregnancy BMI. Across all models, GDM risk significantly increased in the third and fourth quartiles of iron intake. The fourth quartile had an Odds Ratio (OR) of 2.68 (CI 95%, 4.89-1.56; P<0.001) compared to the reference. Heme-iron consumption in the fourth quartiles increased GDM risk. In the second calcium intake model, ORs for the second, third, and fourth quartiles were 0.51 (CI 95%, 0.91-0.25), 0.43 (CI 95%, 0.77-0.24), and 0.35 (CI 95%, 0.63-0.19), respectively (P<0.001 all), reducing GDM risk by 50-65% compared to the first quartile. Dairy consumption in all quartiles of the first and second models was associated with lower GDM risk. Conclusions: Consumption of heme-iron through red and processed meat associated with an increased chance of developing GDM. Dairy intake reduces the chances of developing GDM in pregnant women.

Effects of whole grains on glycemic control: a systematic review and dose-response meta-analysis of prospective cohort studies and randomized controlled trials

PURPOSE

Whole grains have recently been promoted as beneficial to diabetes prevention. However, the evidence for the glycemic benefits of whole grains seems to conflict between the cohort studies and randomized control trials (RCTs). To fill the research gap, we conducted a meta-analysis to determine the effects of whole grains on diabetes prevention and to inform recommendations.

METHODS

We searched PubMed, Clarivate Web of Science, and Cochrane Library until March 2024. We used the risk ratio (RR) of type 2 diabetes to represent the clinical outcomes for cohort studies, while the biomarkers, including fasting blood glucose and insulin, HbA1C, and HOMA-IR, were utilized to show outcomes for RCTs. Dose-response relationships between whole grain intakes and outcomes were tested with random effects meta-regression models and restricted cubic splines models. This study is registered with PROSPERO, CRD42021281639.

RESULTS

Ten prospective cohort studies and 37 RCTs were included. Cohort studies suggested a 50 g/day whole grain intake reduced the risk of type 2 diabetes (RR = 0.761, 95% CI: 0.700 to 0.828, I2 = 72.39%, P < 0.001) and indicated a monotonic inverse relationship between whole grains and type 2 diabetes rate. In RCTs, whole grains significantly reduced fasting blood glucose (Mean difference (MD) = -0.103 mmol/L, 95% CI: -0.178 to -0.028; I2 = 72.99%, P < 0.01) and had modest effects on HbA1C (MD = -0.662 mmol/mol (-0.06%), 95% CI: -1.335 to 0.010; I2 = 64.55%, P = 0.05) and HOMA-IR (MD = -0.164, 95% CI: -0.342 to 0.013; I2 = 33.38%, P = 0.07). The intake of whole grains and FBG, HbA1C, and HOMA-IR were significantly dose-dependent. The restricted spline curves remained flat up to 150 g/day and decreased afterward. Subgroup analysis showed that interventions with multiple whole-grain types were more effective than those with a single type.

CONCLUSION

Our study findings suggest that a daily intake of more than 150 g of whole grain ingredients is recommended as a population approach for diabetes prevention.

Protein intake and type 2 diabetes mellitus: an umbrella review of systematic reviews for the evidence-based guideline for protein intake of the German Nutrition Society

PURPOSE

Protein-rich foods show heterogeneous associations with the risk of type 2 diabetes (T2D) and it remains unclear whether habitual protein intake is related to T2D risk. We carried out an umbrella review of systematic reviews (SR) of randomised trials and/or cohort studies on protein intake in relation to risks of T2D.

METHODS

Following a pre-specified protocol (PROSPERO: CRD42018082395), we retrieved SRs on protein intake and T2D risk published between July 1st 2009 and May 22nd 2022, and assessed the methodological quality and outcome-specific certainty of the evidence using a modified version of AMSTAR 2 and NutriGrade, respectively. The overall certainty of evidence was rated according to predefined criteria.

RESULTS

Eight SRs were identified of which six contained meta-analyses. The majority of SRs on total protein intake had moderate or high methodological quality and moderate outcome-specific certainty of evidence according to NutriGrade, however, the latter was low for the majority of SRs on animal and plant protein. Six of the eight SRs reported risk increases with both total and animal protein. According to one SR, total protein intake in studies was ~ 21 energy percentage (%E) in the highest intake category and 15%E in the lowest intake category. Relative Risks comparing high versus low intake in most recent SRs ranged from 1.09 (two SRs, 95% CIs 1.02-1.15 and 1.06-1.13) to 1.11 (1.05-1.16) for total protein (between 8 and 12 cohort studies included) and from 1.13 (1.08-1.19) to 1.19 (two SRs, 1.11-1.28 and 1.11-1.28) (8-9 cohort studies) for animal protein. However, SRs on RCTs examining major glycaemic traits (HbA1c, fasting glucose, fasting insulin) do not support a clear biological link with T2D risk. For plant protein, some recent SRs pointed towards risk decreases and non-linear associations, however, the majority did not support an association with T2D risk.

CONCLUSION

Higher total protein intake was possibly associated with higher T2D risk, while there is insufficient evidence for a risk increase with higher intakes of animal protein and a risk decrease with plant protein intake. Given that most SRs on plant protein did not indicate an association, there is possibly a lack of an effect.

Association between type 2 diabetes and branched chain amino acids (BCAA); a case-control study

Background

Several amino acids and their derivatives have been implicated in insulin resistance (IR) and Type 2 Diabetes Mellitus (T2DM). This research sought to establish a relationship between the dietary levels of branched-chain amino acids (BCAA) and the risk of T2DM.

Methods

This case-control study was carried out on 4200 participants consisting of 589 people with T2DM and 3611 non-diabetic aged 35 to 70 years residents in Sabzevar, Iran. Data on the economic-social, employment status, medical history, lifestyle, and sleep habits were collected via interview. The food frequency questionnaire (FFQ) was used to check the nutritional status. Participants' dietary BCAA consumption was estimated using Nutritionist IV software.

Results

A significant negative association between the incidence of T2DM and the dietary levels of BCAAs after adjustment for age and sex (OR = 0.972, CI 95%:0.648-0.996, P = 0.022). The negative association remained significant after additional adjustments for body mass index (BMI) and physical activity (OR = 0.967, CI 95%: 0.943-0.992, P = 0.010). Interestingly, a positive association was found between T2DM and total BCAAs (OR = 1.067, CI 95%: 1.017-1.119, P = 0.008), Isoleucine (OR = 1.248, CI 95%: 1.043-1.494, P = 0.016), Leucine (OR = 1.165, CI 95%: 1.046-1.299, P = 0.006) and Valine (OR = 1.274, CI 95%: 1.088-1.492, P = 0.003) after further adjustment for calorie intake.

Conclusions

Our results demonstrate branched-chain amino acids (BCAAs) including isoleucine, leucine, and valine are negatively associated with the incidence of type 2 diabetes (T2DM) after adjusting for age and sex, BMI, and physical activity. However, adjusting for calorie intake reversed the association between T2DM and BCAAs. These findings suggest that the association between BCAAs and T2DM may be influenced by calorie intake. Future longitudinal studies are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01247-9.

Legume consumption in adults and risk of cardiovascular disease and type 2 diabetes: a systematic review and meta-analysis

Objectives

This study aimed to systematically review the evidence for associations between consumption of legumes and cardiovascular disease (CVD), type 2 diabetes (T2D) and their risk factors among healthy adults.

Methods

We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus up to 16 May 2022 for ≥4 weeks long randomized (RCT) and non-randomized controlled trials and prospective cohort studies with follow-up ≥12 months, assessing legume intake (beans/lentils/peas/soybeans, excluding peanuts and legume-products/protein/powder/flour) as the intervention or exposure. Outcomes were CVD, coronary heart disease (CHD), stroke, T2D and in intervention trials only: changes in blood lipids, glycemic markers, and blood pressure. Risk of bias (RoB) was evaluated with Cochrane's RoB2, ROBINS-I, and US Department of Agriculture (USDA)'s RoB-NObS. Effect sizes were pooled using random-effects meta-analyses and expressed as relative risk or weighed mean differences with 95% confidence intervals, heterogeneity quantified as I2. The evidence was appraised according to World Cancer Research Fund's criteria.

Results

Of the 181 full-text articles assessed for eligibility, 47 were included: 31 cohort studies (2,081,432 participants with generally low legume consumption), 14 crossover RCTs (448 participants), one parallel RCT and one non-randomized trial. Meta-analyses of cohort studies were suggestive of null associations for CVD, CHD, stroke and T2D. Meta-analyses of RCTs suggested a protective effect on total cholesterol (mean difference -0.22 mmol/L), low density lipoprotein (LDL)-cholesterol (-0.19 mmol/L), fasting glucose (-0.19 mmol/L), and HOMA-IR (-0.30). Heterogeneity was high (I2 = 52% for LDL-cholesterol, >75% for others). The overall evidence for associations between consumption of legumes and risk of CVD and T2D was considered limited - no conclusion.

Conclusion

Legume consumption was not found to influence risk of CVD and T2D in healthy adult populations with generally low legume consumption. However, protective effects on risk factors, seen in RCTs, lend some support for recommending legume consumption as part of diverse and healthy dietary patterns for prevention of CVD and T2D.

Protein-to-carbohydrate ratio is informative of diet quality and associates with all-cause mortality: Findings from the National Health and Nutrition Examination Survey (2007-2014)

Background

Dietary protein and carbohydrate intake and health outcomes have received extensive attention in recent years. However, the nutritional context in which these associations occur is less studied.

Objectives

We aimed to examine the dietary context associating protein-to-carbohydrate ratio and all-cause mortality in US adults.

Methods

Data from 17,814 adults enrolled in the 2007-2014 NHANES was analyzed. Information on mortality was obtained from the US mortality registry updated in December 2015. Diet quality was assessed using the Healthy Eating Index (HEI) and Total Nutrients Index (TNI). ANCOVA was used to test the mean differences in HEI and TNI scores across %E P:C quintiles. Linear regression examined the association of HEI and TNI with %E P:C. Cox proportional hazards regression evaluated the association between %E P:C and all-cause mortality. A restricted cubic spline examined the non-linear relationship between %E P:C and death.

Results

Low %E P:C was associated with lower HEI and TNI scores while higher %E P:C was associated with healthier HEI and TNI scores. HEI and TNI were positively associated with %E P:C (β = 0.22, 95% CI: 0.19-0.25, and β = 0.16, 95% CI: 0.14-0.18), respectively. Low %E P:C was associated with an increased risk of death from all-cause. The higher HRs (95% CIs) of all-cause mortality were 1.97(1.46-2.65), and 7.35 (2.57-21.03) in the second quintile for the age-sex-ethnicity model, and the fully adjusted model, respectively. There was a significant reverse U-shape relationship between %E P:C and all-cause mortality with P, non-linearity < 0.001.

Conclusion

This study indicates that a low %E P:C that gives emphasis to unhealthy foods increases the risk of death. Hence, it would be useful to consider the complete diet associated with protein intake when making dietary recommendations for populations.

Dietary Protein Sources, Mediating Biomarkers, and Incidence of Type 2 Diabetes: Findings From the Women's Health Initiative and the UK Biobank

OBJECTIVE

Whether and how dietary protein intake is linked to type 2 diabetes (T2D) remains unclear. The aim of this study was to investigate the associations of protein intake with development of T2D and the potential mediating roles of T2D biomarkers.

RESEARCH DESIGN AND METHODS

We included 108,681 postmenopausal women without T2D at baseline from the Women's Health Initiative (WHI) (primary cohort) and 34,616 adults without T2D from the U.K. Biobank (UKB) (replication cohort). Cox proportional hazard models were used for estimation of protein-T2D associations. Mediation analysis was performed to assess the mediating roles of biomarkers in case-control studies nested in the WHI.

RESULTS

In the WHI, 15,842 incident T2D cases were identified during a median follow-up of 15.8 years. Intake of animal protein was associated with increased T2D risk (hazard ratio in comparing the highest to the lowest quintile = 1.31 [95% CI 1.24-1.37]) and plant protein with decreased risk (0.82 [0.78-0.86]). Intakes of red meat, processed meat, poultry, and eggs were associated with increased T2D risk and whole grains with decreased risk. Findings from the UKB were similar. These findings were materially attenuated after additional adjustment for BMI. Substituting 5% energy from plant protein for animal protein was associated with 21% decreased T2D risk (0.79 [0.74-0.84]), which was mediated by levels of hs-CRP, interleukin-6, leptin, and SHBG.

CONCLUSIONS

Findings from these two large prospective cohorts support the notion that substituting plant protein for animal protein may decrease T2D risk mainly by reducing obesity-related inflammation.

Exploring diet associations with Covid-19 and other diseases: a Network Analysis-based approach

The current global pandemic, Covid-19, is a severe threat to human health and existence especially when it is mutating very frequently. Being a novel disease, Covid-19 is impacting the patients with comorbidities and is predicted to have long-term consequences, even for those who have recovered from it. To clearly recognize its impact, it is important to comprehend the complex relationship between Covid-19 and other diseases. It is also being observed that people with good immune system are less susceptible to the disease. It is perceived that if a correlation between Covid-19, other diseases, and diet is realized, then caregivers would be able to enhance their further course of medical action and recommendations. Network Analysis is one such technique that can bring forth such complex interdependencies and associations. In this paper, a Network Analysis-based approach has been proposed for analyzing the interplay of diets/foods along with Covid-19 and other diseases. Relationships between Covid-19, diabetes mellitus type 2 (T2DM), non-alcoholic fatty liver disease (NAFLD), and diets have been curated, visualized, and further analyzed in this study so as to predict unknown associations. Network algorithms including Louvain graph algorithm (LA), K nearest neighbors (KNN), and Page rank algorithms (PR) have been employed for predicting a total of 60 disease-diet associations, out of which 46 have been found to be either significant in disease risk prevention/mitigation or in its progression as validated using PubMed literature. A precision of 76.7% has been achieved which is significant considering the involvement of a novel disease like Covid-19. The generated interdependencies can be further explored by medical professionals and caregivers in order to plan healthy eating patterns for Covid-19 patients. The proposed approach can also be utilized for finding beneficial diets for different combinations of comorbidities with Covid-19 as per the underlying health conditions of a patient. Graphical abstract.

Variety and quantity of dietary protein intake from different sources and risk of new-onset diabetes: a Nationwide Cohort Study in China

BACKGROUND

The relation of the variety and quantity of different sources of dietary proteins intake and diabetes remains uncertain. We aimed to investigate the associations between the variety and quantity of proteins intake from eight major food sources and new-onset diabetes, using data from the China Health and Nutrition Survey (CHNS).

METHODS

16,260 participants without diabetes at baseline from CHNS were included. Dietary intake was measured by three consecutive 24-h dietary recalls combined with a household food inventory. The variety score of protein sources was defined as the number of protein sources consumed at the appropriate level, accounting for both types and quantity of proteins. New-onset diabetes was defined as self-reported physician-diagnosed diabetes or fasting glucose ≥7.0mmol/L or glycated hemoglobin ≥6.5% during the follow-up.

RESULTS

During a median follow-up of 9.0 years, 1100 (6.8%) subjects developed diabetes. Overall, there were U-shaped associations of percentages energy from total protein, whole grain-derived and poultry-derived proteins with new-onset diabetes; J-shaped associations of unprocessed or processed red meat-derived proteins with new-onset diabetes; a reverse J-shaped association of the fish-derived protein with new-onset diabetes; L-shaped associations of egg-derived and legume-derived proteins with new-onset diabetes; and a reverse L-shaped association of the refined grain-derived protein with new-onset diabetes (all P values for nonlinearity<0.001). Moreover, a significantly lower risk of new-onset diabetes was found in those with a higher variety score of protein sources (per score increment; HR, 0.69; 95%CI, 0.65-0.72).

CONCLUSIONS

There was an inverse association between the variety of proteins with appropriate quantity from different food sources and new-onset diabetes.

Ultra-processed food and risk of type 2 diabetes: a systematic review and meta-analysis of longitudinal studies

BACKGROUND

The consumption of some food groups is associated with the risk of diabetes. However, there is no evidence from meta-analysis which evaluates the consumption of ultra-processed products in the risk of diabetes. This study aimed to review the literature assessing longitudinally the association between consumption of ultra-processed food and the risk of type 2 diabetes and to quantify this risk through a meta-analysis.

METHODS

We conducted a systematic review and meta-analysis with records from PubMed, Latin American and Caribbean Literature in Health Sciences (LILACS), Scielo, Scopus, Embase, and Web of Science. We included longitudinal studies assessing ultra-processed foods and the risk of type 2 diabetes. The review process was conducted independently by two reviewers. The Newcastle Ottawa scale assessed the quality of the studies. A meta-analysis was conducted to assess the effect of moderate and high consumption of ultra-processed food on the risk of diabetes.

RESULTS

In total 2272 records were screened, of which 18 studies, including almost 1.1 million individuals, were included in this review and 72% showed a positive association between ultra-processed foods and the risk of diabetes. According to the studies included in the meta-analysis, compared with non-consumption, moderate intake of ultra-processed food increased the risk of diabetes by 12% [relative risk (RR): 1.12; 95% confidence interval (CI): 1.06-1.17, I2 = 24%], whereas high intake increased risk by 31% (RR: 1.31; 95% CI: 1.21-1.42, I2 = 60%).

CONCLUSIONS

The consumption of ultra-processed foods increased the risk for type 2 diabetes as dose-response effect, with moderate to high credibility of evidence.

Dietary Intake of Adult Residents in Luxembourg Taking Part in Two Cross-Sectional Studies-ORISCAV-LUX (2007-2008) and ORISCAV-LUX 2 (2016-2017)

Background: A balanced diet is an important lifestyle component and has been associated with a reduced risk of chronic diseases. Objectives: To assess dietary intake of adult residents in Luxembourg taking part in two population-based cross-sectional studies (ORISCAV-LUX, 2007–2008 and ORISCAV-LUX 2, 2016–2017). Methods: Dietary intake of the study participants (1242 in 2007/08 and 1326 in 2016/17), 25–69 years old, were evaluated using food-frequency questionnaires (134 items in 2007/2008 and 174 items in 2016/2017) according to the French ANSES-CIQUAL food composition database. Both food-group- and nutrient-based analyses were conducted. Results: Dietary patterns in ORISCAV-LUX 2, 2016–2017, were characterized by an increase in the estimated marginal means (EMM) of the intake of energy, total fat, saturated fatty acids, alcohol, and decreased EMM of total carbohydrates, magnesium, and calcium compared to 2007/08. We also observed an increased EMM of the intake of protein-rich food items and ready-to-eat foods/fast foods, together with a decreased intake of grains, dairy products, and vegetables (all p-values <0.05, linear mixed models). The intake of most micronutrients was stable or slightly increased in ORISCAV-LUX 2 vs. ORISCAV-LUX, except for the drop in magnesium and calcium, and generally met recommendations, in particular, EFSA population reference intakes (PRI), except for vitamin D. Conclusions: Though most micronutrient recommendations were met, nutrient consumption in terms of high energy, total fat, and sodium, as well as low carbohydrates, were not aligned with recommendations for balanced eating.

Lower Dietary Intake of Plant Protein Is Associated with Genetic Risk of Diabetes-Related Traits in Urban Asian Indian Adults

The increasing prevalence of type 2 diabetes among South Asians is caused by a complex interplay between environmental and genetic factors. We aimed to examine the impact of dietary and genetic factors on metabolic traits in 1062 Asian Indians. Dietary assessment was performed using a validated semi-quantitative food frequency questionnaire. Seven single nucleotide polymorphisms (SNPs) from the Transcription factor 7-like 2 and fat mass and obesity-associated genes were used to construct two metabolic genetic risk scores (GRS): 7-SNP and 3-SNP GRSs. Both 7-SNP GRS and 3-SNP GRS were associated with a higher risk of T2D (p = 0.0000134 and 0.008, respectively). The 3-SNP GRS was associated with higher waist circumference (p = 0.010), fasting plasma glucose (FPG) (p = 0.002) and glycated haemoglobin (HbA1c) (p = 0.000066). There were significant interactions between 3-SNP GRS and protein intake (% of total energy intake) on FPG (Pinteraction = 0.011) and HbA1c (Pinteraction = 0.007), where among individuals with lower plant protein intake (<39 g/day) and those with >1 risk allele had higher FPG (p = 0.001) and HbA1c (p = 0.00006) than individuals with ≤1 risk allele. Our findings suggest that lower plant protein intake may be a contributor to the increased ethnic susceptibility to diabetes described in Asian Indians. Randomised clinical trials with increased plant protein in the diets of this population are needed to see whether the reduction of diabetes risk occurs in individuals with prediabetes.

Associations of Total Legume, Pulse, and Soy Consumption with Incident Type 2 Diabetes: Federated Meta-Analysis of 27 Studies from Diverse World Regions

BACKGROUND

The consumption of legumes is promoted as part of a healthy diet in many countries but associations of total and types of legume consumption with type 2 diabetes (T2D) are not well established. Analyses across diverse populations are lacking despite the availability of unpublished legume consumption data in prospective cohort studies.

OBJECTIVE

To examine the prospective associations of total and types of legume intake with the risk of incident T2D.

METHODS

Meta-analyses of associations between total legume, pulse, and soy consumption and T2D were conducted using a federated approach without physical data-pooling. Prospective cohorts were included if legume exposure and T2D outcome data were available and the cohort investigators agreed to participate. We estimated incidence rate ratios (IRRs) and CIs of associations using individual participant data including ≤42,473 incident cases among 807,785 adults without diabetes in 27 cohorts across the Americas, Eastern Mediterranean, Europe, and Western Pacific. Random-effects meta-analysis was used to combine effect estimates and estimate heterogeneity.

RESULTS

Median total legume intake ranged from 0-140 g/d across cohorts. We observed a weak positive association between total legume consumption and T2D (IRR = 1.02, 95% CI: 1.01 to 1.04) per 20 g/d higher intake, with moderately high heterogeneity (I2 = 74%). Analysis by region showed no evidence of associations in the Americas, Eastern Mediterranean, and Western Pacific. The positive association in Europe (IRR = 1.05, 95% CI: 1.01 to 1.10, I2 = 82%) was mainly driven by studies from Germany, UK, and Sweden. No evidence of associations was observed for the consumption of pulses or soy.

CONCLUSIONS

These findings suggest no evidence of an association of legume intakes with T2D in several world regions. The positive association observed in some European studies warrants further investigation relating to overall dietary contexts in which legumes are consumed, including accompanying foods which may be positively associated with T2D.

Egg, cholesterol and protein intake and incident type 2 diabetes mellitus: Results of repeated measurements from a prospective cohort study

BACKGROUND & AIMS

Epidemiological evidence on the associations of egg, cholesterol and protein intake with risk of type 2 diabetes is inconsistent. Therefore, we conducted this study to explore these associations among Chinese adults.

METHODS

Data from 4 waves (2004, 2006, 2009 and 2011) of the China Health and Nutrition Survey were used. A multistage random-cluster sampling method was employed to recruit the participants in both rural and urban areas. We included individuals who participated in 2004 and any waves afterwards. Those 1) below 18 years of age; 2) with diabetes at baseline; or 3) with extreme energy intake (men: <800 kcal or >6000 kcal; women: <600 kcal or >4000 kcal) were excluded. Respondents were classified into four groups according to quartiles of egg, cholesterol and protein intake per day. Numbers of eggs per day were calculated by dividing egg intake in grams by 50 g. Diagnosis of type 2 diabetes was self-reported. Logistic generalized estimation equation models were employed.

RESULTS

There were 7312 individuals included in 2004, 6390 in 2006, 4826 in 2009 and 4963 in 2011. The mean age of participants at baseline was 48.3 years and 47.2% were men. Over an average of 5.8-y follow-up, 209 developed type 2 diabetes. After adjustment for demographic, lifestyle and dietary confounders, the odds ratio of type 2 diabetes for those in the highest compared with the lowest protein intake quartile was 2.38 (95% CI: 1.43, 3.98). The odds ratio of individuals with ≥3 eggs/day versus none was 3.76 (95% CI, 2.05, 6.90). Cholesterol intake was not associated with type 2 diabetes.

CONCLUSIONS

Individuals with the highest protein intake had over a 2-fold increased risk of type 2 diabetes compared with those with the lowest protein intake. A high intake of egg, but not dietary cholesterol, was associated with type 2 diabetes. This association warrants further investigation.

Western Dietary Patterns, Foods, and Risk of Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

An increasing number of epidemiological studies suggest that adherence to Western dietary patterns (WDPs) is associated with risk of gestational diabetes mellitus (GDM), but results remain inconsistent. Therefore, we conducted a systematic review and meta-analysis of the effect of WDPs and typical Western dietary foods on GDM. A literature search was performed in PubMed, Embase, Web of Knowledge, and the Cochrane Library up to December 2019. Cohort studies investigating the combined associations of WDPs with incidence of GDM were included. Reviewers were paired, and they independently reviewed and assessed studies, extracted data, and evaluated study quality. Pooled HRs were calculated using random-effects models. Heterogeneity and publication bias tests were also conducted. Twenty-one prospective cohort studies with 191,589 participants, including 12,331 women with GDM, were included in our analysis. The pooled risk ratio (RR) of WDPs was 1.52 (95% CI: 1.21, 1.91), indicating a significant association with GDM risk in Western countries. Potatoes (pooled RR: 1.12; 95% CI: 0.93, 1.35) showed a nonsignificant (P > 0.05) relation to GDM risk. However, consumption of animal meat (pooled RR: 1.35; 95% CI: 1.16, 1.57) and fast food (pooled RR: 1.75; 95% CI: 1.41, 2.19) showed a positive association with the risk of developing GDM. Subgroup analysis demonstrated that the consumption of red meat and processed red meat increased the risk of GDM more than either poultry or fish intake. Our study provides further evidence for understanding the relation between dietary factors and increased GDM risk and contributes to reducing the incidence of GDM through healthy diets.

Associations of carbohydrates and carbohydrate-rich foods with incidence of type 2 diabetes

Dietary carbohydrates have long been expected to be associated with risk of type 2 diabetes; however, the associations for many carbohydrates and carbohydrate-rich foods remain inconclusive. This study analysed associations between intakes of six types of carbohydrates and thirteen carbohydrate-rich foods with incident type 2 diabetes in 26 622 participants (61 % women) in the Malmö Diet and Cancer Study in southern Sweden. Dietary intake was assessed at baseline (1991-1996) by using a modified diet history method. During mean follow-up of 18 years, 4046 cases were identified. Adjusting for potential confounders (including lifestyle, BMI and dietary factors), comparing highest v. lowest quintile of intake, monosaccharides (hazard ratio (HR) 0·88; 95 % CI 0·79, 0·98; Ptrend = 0·02) and fruits (HR 0·91; 95 % CI 0·82, 1·01; Ptrend = 0·03) were inversely associated with incident type 2 diabetes, while disaccharides (HR 1·17; 95 % CI 1·04, 1·30; Ptrend = 0·002) and sweets (HR 1·09; 95 % CI 1·00, 1·19; Ptrend = 0·02) were positively associated. After stratification by sex, marmalade/honey/jam (HR 0·82; 95 % CI 0·72, 0·94; Ptrend < 0·001) and vegetables (HR 0·85; 95 % CI 0·73, 0·98; Ptrend = 0·06) were inversely associated with incident type 2 diabetes in men and chocolate (HR 1·26; 95 % CI 1·09, 1·46; Ptrend < 0·001) was positively associated in women. In conclusion, we identified inverse associations for intake of monosaccharides and fruits with type 2 diabetes risk, and positive associations for disaccharides and sweets. Additional sex-specific associations were also identified. Future studies are needed to explore these associations further.

Dietary Protein to Carbohydrate Ratio and Incidence of Metabolic Syndrome in Korean Adults Based on a Long-Term Prospective Community-Based Cohort

Interest in high protein diets has recently been increasing for reduction of weight or management of cardiometabolic risks. However, studies on high protein, low carbohydrate diet in Asians are limited. This study aimed to estimate whether the dietary ratio of protein (%) to carbohydrate (%) from total energy intake (p/c ratio) is associated with the risk of metabolic syndrome (MS) and its components in Korean adults using a long-term prospective cohort. A total of 6335 participants from the Korean Genome and Epidemiology Study, aged between 40 and 69 years, with no previous diagnosis of MS, cardiovascular diseases, or cancer at baseline (2001–2002) were followed until 2013. Dietary intake was measured using a validated semiquantitative food-frequency questionnaire. MS components were measured at baseline and every 2 years. During a mean of 7.7 years of follow up, 1198 (36.1%) men and 1169 (38.8%) women developed MS. The multivariate adjusted hazard ratio (HR) of incident MS was 1.43 (95% confidence interval, 1.09–1.89) for the highest compared lowest quintile of p/c ratio in men. When evaluating each component of MS, higher dietary p/c ratio was associated with an increased risk of high triglyceride and fasting glucose in men (HR for fifth vs. first quintile, 1.39 and 1.41 in Model 3, respectively). However, we observed no associations with incident MS and its components and dietary p/c ratio in women. In conclusion, we found that high dietary p/c ratio was associated with an increased risk of MS and its components (i.e., increased triglycerides and fasting glucose) in men. Our study suggested that even if the absolute amount of protein intake is not large, an increased p/c ratio may increase the risk of metabolic diseases.

Facility-dependent metabolic phenotype and gut bacterial composition in CD-1 mice from a single vendor: A brief report

Utilization of murine models remains a valuable tool in biomedical research, yet, disease phenotype of mice across studies can vary considerably. With advances in next generation sequencing, it is increasingly recognized that inconsistencies in host phenotype can be attributed, at least in part, to differences in gut bacterial composition. Research with inbred murine strains demonstrates that housing conditions play a significant role in variations of gut bacterial composition, however, few studies have assessed whether observed variation influences host phenotype in response to an intervention. Our study initially sought to examine the effects of a long-term (9-months) dietary intervention (i.e., diets with distinct fatty acid compositions) on the metabolic health, in particular glucose homeostasis, of genetically-outbred male and female CD-1 mice. Yet, mice were shipped from two different husbandry facilities of the same commercial vendor (Cohort A and B, respectively), and we observed throughout the study that diet, sex, and aging differentially influenced the metabolic phenotype of mice depending on their husbandry facility of origin. Examination of the colonic bacteria of mice revealed distinct bacterial compositions, including 23 differentially abundant genera and an enhanced alpha diversity in mice of Cohort B compared to Cohort A. We also observed that a distinct metabolic phenotype was linked with these differentially abundant bacteria and indices of alpha diversity. Our findings support that metabolic phenotypic variation of mice of the same strain but shipped from different husbandry facilities may be influenced by their colonic bacterial community structure. Our work is an important precautionary note for future research of metabolic diseases via mouse models, particularly those that seek to examine factors such diet, sex, and aging.

Consumption of red meat, genetic susceptibility, and risk of LADA and type 2 diabetes

Purpose

Red meat consumption is positively associated with type 1 (T1D) and type 2 (T2D) diabetes. We investigated if red meat consumption increases the risk of latent autoimmune diabetes in adults (LADA) and T2D, and potential interaction with family history of diabetes (FHD), HLA and TCF7L2 genotypes.

Methods

Analyses were based on Swedish case–control data comprising incident cases of LADA (n = 465) and T2D (n = 1528) with matched, population-based controls (n = 1789; n = 1553 in genetic analyses). Multivariable-adjusted ORs in relation to self-reported processed and unprocessed red meat intake were estimated by conditional logistic regression models. Attributable proportion (AP) due to interaction was used to assess departure from additivity of effects.

Results

Consumption of processed red meat was associated with increased risk of LADA (per one servings/day OR 1.27, 95% CI 1.07–1.52), whereas no association was observed for unprocessed red meat. For T2D, there was no association with red meat intake once BMI was taken into account. The combination of high (> 0.3 servings/day vs. less) processed red meat intake and high-risk HLA-DQB1 and -DRB1 genotypes yielded OR 8.05 (95% CI 4.86–13.34) for LADA, with indications of significant interaction (AP 0.53, 95% CI 0.32–0.73). Results were similar for the combination of FHD-T1D and processed red meat. No interaction between processed red meat intake and FHD-T2D or risk variants of TCF7L2 was seen in relation to LADA or T2D.

Conclusion

Consumption of processed but not unprocessed red meat may increase the risk of LADA, especially in individuals with FHD-T1D or high-risk HLA genotypes.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02285-2) contains supplementary material, which is available to authorized users.

Legume and soy intake and risk of type 2 diabetes: a systematic review and meta-analysis of prospective cohort studies

BACKGROUND

Previous findings on the associations of legume and soy intake with the risk of type 2 diabetes are conflicting.

OBJECTIVE

We aimed to summarize the longitudinal associations between legume and soy intake and risk of type 2 diabetes.

METHODS

We searched for relevant prospective cohort studies in PubMed, EMBASE, and Ovid up to August 2019. Study-specific, multivariable-adjusted RRs and 95% CIs were pooled by random-effects models.

RESULTS

We identified 15 unique cohorts including 565,810 individuals and 32,093 incident cases. The summary RRs (95% CIs) of incident type 2 diabetes were 0.95 (0.79, 1.14; NS) for total legumes, 0.83 (0.68, 1.01; NS) for total soy, 0.89 (0.71, 1.11; NS) for soy milk, 0.92 (0.84, 0.99) for tofu, 0.84 (0.75, 0.95) for soy protein, and 0.88 (0.81, 0.96) for soy isoflavones, respectively. High heterogeneity was found for total legumes (I2 = 84.8%), total soy (I2 = 90.8%), and soy milk (I2 = 91.7%). Potential sources of heterogeneity were not evident for total legumes or soy milk, whereas for total soy, geographic location (Asia, United States; P = 0.04) and study quality (high, moderate, or low; P = 0.02) significantly predicted heterogeneity. In dose-response analysis, significant linear inverse associations were observed for tofu, soy protein, and soy isoflavones (all P < 0.05). Overall quality of evidence was rated as moderate for total legumes and low for total soy and soy subtypes.

CONCLUSIONS

Dietary intakes of tofu, soy protein, and soy isoflavones, but not total legumes or total soy, are inversely associated with incident type 2 diabetes. Our findings support recommendations to increase intakes of certain soy products for the prevention of type 2 diabetes. However, the overall quality of evidence was low and more high-quality evidence from prospective studies is needed. This trial was registered as PROSPERO CRD42019126403 (https://www.crd.york.ac.uk/PROSPERO).

Specificity, Dose Dependency, and Kinetics of Markers of Chicken and Beef Intake Using Targeted Quantitative LC-MS/MS: A Human Intervention Trial

SCOPE

Common methods for food intake assessment are error-prone. Estimating food intake via metabolite biomarkers in blood/urine is challenged by inter-individual variation. Here, meat intake markers based on criteria defined within the FoodBAll consortium, including dose dependency, specificity, kinetics, and their ability to predict meat dose, are evaluated.

METHODS AND RESULTS

In two randomized human interventions, meat at different doses are consumed. Plasma concentrations of 100 analytes, including previously proposed meat intake markers, are determined at different time points up to 24 h after meat ingestion using targeted liquid chromatography-tandem mass spectrometry. Plasma concentrations of π-methylhistidine (π-M-His) correlated best with the chicken meat amount consumed even after 24 h (R² = 0.96). Both, anserine and π-M-His show first-order elimination kinetics, irrespective of meat dose (t_1/2 is 1.4 and 5.9 h, respectively). Surprisingly, π-M-His best predicted the amount of beef consumed, albeit at lower concentrations. Furthermore, trimethylamine-N-oxide (TMAO) increases only after beef, while dimethylglycine only after chicken consumption. The lack of baseline concentrations for π-M-His and anserine is likely the strength of these compounds to predict meat dose.

CONCLUSION

Quantitative assessment of meat intake within 24 h is most accurate with π-M-His, whereas TMAO and dimethylglycine best discriminate between chicken and beef.

Carbohydrate-restricted diet alters the gut microbiota, promotes senescence and shortens the life span in senescence-accelerated prone mice

This study examined the effects of a carbohydrate-restricted diet on aging, brain function, intestinal bacteria and the life span to determine long-term carbohydrate-restriction effects on the aging process in senescence-accelerated prone mice (SAMP8). Three-week-old male SAMP8 were divided into three groups after a week of preliminary feeding. One group was given a controlled diet, while the others fed on high-fat and carbohydrate-restricted diets, respectively. The mice in each group were further divided into two subgroups, of which one was the longevity measurement group. The other groups fed ad libitum until the mice were 50 weeks old. Before the test period termination, passive avoidance test evaluated the learning and memory abilities. Following the test period, serum and various mice organs were obtained and submitted for analysis. The carbohydrate-restricted diet group exhibited significant decrease in the survival rate as compared to the other two diet groups. The passive avoidance test revealed a remarkable decrease in the learning and memory ability of carbohydrate-restricted diet group as compared to the control-diet group. Measurement of lipid peroxide level in tissues displayed a marked increase in the brain and spleen of carbohydrate-restricted diet group than the control-diet and high-fat diet groups. Furthermore, notable serum IL-6 and IL-1β level (inflammation indicators) elevations, decrease in Enterobacteria (with anti-inflammatory action), increase in inflammation-inducing Enterobacteria and lowering of short-chain fatty acids levels in cecum were observed in the carbohydrate-restricted diet group. Hence, carbohydrate-restricted diet was revealed to promote aging and shortening of life in SAMP8.

Dietary Protein Consumption and the Risk of Type 2 Diabetes: ADose-Response Meta-Analysis of Prospective Studies

The relationship between dietary protein consumption and the risk of type 2 diabetes (T2D) has been inconsistent. The aim of this meta-analysis was to explore the relations between dietary protein consumption and the risk of T2D. We conducted systematic retrieval of prospective studies in PubMed, Embase, and Web of Science. Summary relative risks were compiled with a fixed effects model or a random effects model, and a restricted cubic spline regression model and generalized least squares analysis were used to evaluate the diet–T2D incidence relationship. T2D risk increased with increasing consumption of total protein and animal protein, red meat, processed meat, milk, and eggs, respectively, while plant protein and yogurt had an inverse relationship. A non-linear association with the risk for T2D was found for the consumption of plant protein, processed meat, milk, yogurt, and soy. This meta-analysis suggests that substitution of plant protein and yogurt for animal protein, especially red meat and processed meat, can reduce the risk for T2D.

The Association between Maternal Dietary Protein Intake and Risk of Gestational Diabetes Mellitus

BACKGROUND

The amount and type of dietary protein affect glucose metabolism. However, the association between dietary protein intake and gestational diabetes mellitus (GDM) risk is vague. We examined this association. Methods: We included 152 GDM and 168 non-GDM participants (total 320), age 18-45 years from Arash Women's Hospital, Tehran, Iran. Protein intake was ascertained from 168-item Food Frequency Questionnaire at 24-40 weeks' gestation. GDM was defined as fasting blood sugar >95 mg/dL and/or oral glucose tolerance test >155 mg/dL. Dietary data were assessed using N4 software and statistical analysis was performed using SPSS 21. We tested the association between the amount of protein consumed from red and processed meat, poultry, dairy, egg, seafood, and vegetable plus sociodemographic and lifestyle covariates and GDM risk using multivariate logistic regression analysis.

RESULTS

There was a significant association between the physical activity (P < 0.035), socioeconomic status (P < 0.013), body mass index, age, and each trimester's weight (P < 0.001), and risk of GDM. No significant association was observed between the intake of protein from major protein sources and risk of GDM. The only significant association was observed for egg consumption which was lower in GDM participants (P = 0.004), yet this association turned nonsignificant after adjustment for confounders, except for the fourth quartile (odds ratio: 0.43, 95% confidence interval: 0.208, 0.893).

CONCLUSIONS

According to our findings, dietary intake of total and major protein sources could not affect the GDM risk. Differences between Iranian and Western population and the reverse causality might be the main reasons for this nonsignificant association.

Legume Consumption and Cardiometabolic Health

Legumes are key components of several plant-based diets and are recognized as having a wide range of potential health benefits. Previous systematic reviews and meta-analyses have summarized the evidence regarding different cardiometabolic outcomes, such as cardiovascular disease (CVD) and type 2 diabetes (T2D), and legume consumption. However, those studies did not differentiate between nonsoy and soy legumes, which have different nutritional profiles. The aim of the present updated review, therefore, was to summarize and meta-analyze the published evidence regarding legume consumption (making a distinction between nonsoy and soy legumes) and cardiometabolic diseases. In addition, we reviewed randomized clinical trials assessing the effect of legume consumption on CVD risk factors in order to understand their associations. The results revealed a prospective, significant inverse association between total legume consumption and CVD and coronary heart disease risk, whereas a nonsignificant association was observed with T2D and stroke. In the stratified analysis by legume subtypes, only nonsoy legumes were associated with lower risk of T2D. Unfortunately, owing to the paucity of studies analyzing legumes and CVD, it was not possible to stratify the analysis for these outcomes. Because of the high degree of heterogeneity observed for most of the outcomes and the few studies included in some analyses, further prospective studies are warranted to determine the potential role of legume consumption on CVD and T2D.

Prevention of Type 2 Diabetes by Lifestyle Changes: A Systematic Review and Meta-Analysis

Prevention of type 2 diabetes (T2D) is a great challenge worldwide. The aim of this evidence synthesis was to summarize the available evidence in order to update the European Association for the Study of Diabetes (EASD) clinical practice guidelines for nutrition therapy. We conducted a systematic review and, where appropriate, meta-analyses of randomized controlled trials (RCTs) carried out in people with impaired glucose tolerance (IGT) (six studies) or dysmetabolism (one study) to answer the following questions: What is the evidence that T2D is preventable by lifestyle changes? What is the optimal diet (with a particular focus on diet quality) for prevention, and does the prevention of T2D result in a lower risk of late complications of T2D? The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was applied to assess the certainty of the trial evidence. Altogether seven RCTs (N = 4090) fulfilled the eligibility criteria and were included in the meta-analysis. The diagnosis of incident diabetes was based on an oral glucose tolerance test (OGTT). The overall risk reduction of T2D by the lifestyle interventions was 0.53 (95% CI 0.41; 0.67). Most of the trials aimed to reduce weight, increase physical activity, and apply a diet relatively low in saturated fat and high in fiber. The PREDIMED trial that did not meet eligibility criteria for inclusion in the meta-analysis was used in the final assessment of diet quality. We conclude that T2D is preventable by changing lifestyle and the risk reduction is sustained for many years after the active intervention (high certainty of evidence). Healthy dietary changes based on the current recommendations and the Mediterranean dietary pattern can be recommended for the long-term prevention of diabetes. There is limited or insufficient data to show that prevention of T2D by lifestyle changes results in a lower risk of cardiovascular and microvascular complications.

Associations between Dietary Pulses Alone or with Other Legumes and Cardiometabolic Disease Outcomes: An Umbrella Review and Updated Systematic Review and Meta-analysis of Prospective Cohort Studies

To update the European Association for the Study of Diabetes clinical practice guidelines for nutrition therapy, we conducted an umbrella review and updated systematic review and meta-analysis (SRMA) of prospective cohort studies of the association between dietary pulses with or without other legumes and cardiometabolic disease outcomes. We searched the PubMed, MEDLINE, EMBASE, and Cochrane databases through March 2019. We included the most recent SRMAs of prospective cohort studies and new prospective cohort studies published after the census dates of the included SRMAs assessing the relation between dietary pulses with or without other legumes and incidence and mortality of cardiovascular diseases (CVDs) [including coronary heart disease (CHD), myocardial infarction (MI), and stroke], diabetes, hypertension, and/or obesity. Two independent reviewers extracted data and assessed risk of bias. Risk estimates were pooled using the generic inverse variance method and expressed as risk ratios (RRs) with 95% CIs. The overall certainty of the evidence was assessed using the GRADE approach. Six SRMAs were identified and updated to include 28 unique prospective cohort studies with the following number of cases for each outcome: CVD incidence, 10,261; CVD mortality, 16,168; CHD incidence, 7786; CHD mortality, 3331; MI incidence, 2585; stroke incidence, 8570; stroke mortality, 2384; diabetes incidence, 10,457; hypertension incidence, 83,284; obesity incidence, 8125. Comparing the highest with the lowest level of intake, dietary pulses with or without other legumes were associated with significant decreases in CVD (RR: 0.92; 95% CI: 0.85, 0.99), CHD (RR: 0.90; 95% CI: 0.83, 0.99), hypertension (RR: 0.91; 95% CI: 0.86, 0.97), and obesity (RR: 0.87; 95% CI: 0.81, 0.94) incidence. There was no association with MI, stroke, and diabetes incidence or CVD, CHD, and stroke mortality. The overall certainty of the evidence was graded as "low" for CVD incidence and "very low" for all other outcomes. Current evidence shows that dietary pulses with or without other legumes are associated with reduced CVD incidence with low certainty and reduced CHD, hypertension, and obesity incidence with very low certainty. More research is needed to improve our estimates. This trial was registered at clinicaltrials.gov as NCT03555734.

Dietary protein intake and subsequent risk of type 2 diabetes: a dose-response meta-analysis of prospective cohort studies

AIMS

Dietary proteins, including those obtained from animal and plant sources, have inconsistently been correlated with type 2 diabetes mellitus (T2DM) risk. Therefore, a meta-analysis was conducted to evaluate the association between dietary proteins and the risk of T2DM.

METHODS

Prospective cohort studies published until November 2018 were systematically searched in PubMed, Embase, and the Cochrane library. The pooled relative risks (RRs) were calculated with 95% confidence intervals (CIs) using the random-effects model.

RESULTS

Ten articles involving a total of 21 cohorts were included in the final meta-analysis. A total of 487,956 individuals were recruited in these studies and 38,350 T2DM cases were reported. Analysis of the pooled RRs indicated that high total protein intake was associated with an increased risk of T2DM (RR 1.10; P = 0.006), whereas moderate total protein intake was not significantly associated with T2DM risk (RR 1.00; P = 0.917). Moreover, a higher risk of T2DM was observed with high animal protein intake (RR 1.13; P = 0.013), whereas moderate animal protein intake had little or no effect on T2DM risk (RR 1.06; P = 0.058). Finally, high intake of plant protein did not affect T2DM risk (RR 0.93; P = 0.074), whereas moderate intake was associated with a reduced risk of T2DM (RR 0.94; P < 0.001).

CONCLUSIONS

The results of this study indicate that high total protein and animal protein intakes are associated with an increased risk of T2DM, whereas moderate plant protein intake is associated with a decreased risk of T2DM.

Association between dairy intake and the risk of contracting type 2 diabetes and cardiovascular diseases: a systematic review and meta-analysis with subgroup analysis of men versus women

CONTEXT

The association between dairy product intake and the risk of developing type 2 diabetes (T2D) or cardiovascular disease (CVD) has been investigated in several studies, but little attention was given to the role of sex as a moderator of these associations. (In this article, the term "sex" is used to denote the biologically-based differences between males and females.).

OBJECTIVE

This meta-analysis examines whether dairy consumption has different effects on T2D and CVD in men and women.

DATA SOURCES

The PubMed database and previous reviews were searched for cohort studies published between 2006 and 2016.

DATA EXTRACTION AND ANALYSIS

Reported risk ratios (RRs) for T2D/CVD with high versus low dairy intake were extracted. A random-effects model has been used to calculate the pooled RR. A subgroup analysis was conducted to compare the results for men and women.

RESULTS

The present meta-analysis of 201 studies found that T2D (n = 16 studies) and CVD (n = 13 studies) are inversely associated with dairy intake. Subgroup analysis for sex showed that the association between dairy intake and T2D and between dairy intake and CVD are significant in women (RR for T2D = 0.868; 95%CI, 0.82-0.92; P < 0.001; RR for CVD = 0.837; 95%CI, 0.75-0.93; P < 0.001) but not in men.

CONCLUSIONS

There is an inverse association between high dairy intake and the risk of developing T2D and CVD in women.

Protein intake and the incidence of pre-diabetes and diabetes in 4 population-based studies: the PREVIEW project

BACKGROUND

Data on the relationship between protein intake and the risk of type 2 diabetes are conflicting.

OBJECTIVE

We studied prospective associations between the intake of total, plant-based, and animal protein and the risk of pre-diabetes and diabetes in 4 population-based studies included in the PREVIEW project.

METHODS

Analyses were conducted with the use of data from 3 European cohorts and 1 Canadian cohort, including 78,851 participants. Protein intake was assessed through the use of harmonized data from food-frequency questionnaires or 3-d dietary records. Cohort-specific incidence ratios (IRs) were estimated for pre-diabetes and diabetes, adjusting for general characteristics, lifestyle and dietary factors, disease history, and body mass index (BMI) and waist circumference; results were pooled based on a random-effects meta-analysis.

RESULTS

Higher total protein intake (g · kg-1 · d-1) was associated with lower incidences of pre-diabetes and diabetes (pooled IRs: 0.84; 95% CI: 0.82, 0.87 and 0.49; 95% CI: 0.28, 0.83, respectively); plant-based protein intake was the main determinant (pooled IRs: 0.83; 95% CI: 0.81, 0.86 and 0.53; 95% CI: 0.36, 0.76, respectively). Substituting 2 energy percentage (E%) protein at the expense of carbohydrates revealed increased risks of pre-diabetes and diabetes (pooled IRs: 1.04; 95% CI: 1.01, 1.07 and 1.09; 95% CI: 1.01, 1.18, respectively). Except for the associations between intakes of total protein and plant-based protein (g · kg-1 · d-1) and diabetes, all other associations became nonsignificant after adjustment for BMI and waist circumference.

CONCLUSIONS

Higher protein intake (g · kg-1 · d-1) was associated with a lower risk of pre-diabetes and diabetes. Associations were substantially attenuated after adjustments for BMI and waist circumference, which demonstrates a crucial role for adiposity and may account for previous conflicting findings. This study was registered at ISRCTN as ISRCTN31174892.

Perspective: Refined Grains and Health: Genuine Risk, or Guilt by Association?

Refined grain intake is widely assumed to be associated with adverse health outcomes, including increased risk for cardiovascular disease (CVD), type 2 diabetes (T2D), and obesity. The 2015 Dietary Guidelines Advisory Committee recommended that to improve dietary quality, the US population should replace most refined grains with whole grains. This recommendation was based largely on results from studies that examined dietary patterns, not separate food groups. A Western dietary pattern typically includes red and processed meat, sugar-sweetened foods and beverages, French fries, and high-fat dairy products, as well as refined grains, and has been linked to increased risk of many chronic diseases. However, when evaluated as a distinct food category, 11 meta-analyses of prospective cohort studies, which included a total of 32 publications with data from 24 distinct cohorts, demonstrated that refined grain intake was not associated with all-cause mortality, T2D, CVD, coronary heart disease (CHD), stroke, hypertension, or cancer. By contrast, consumption of red and processed meat was consistently associated with increased risk of these same health outcomes. Refined grain consumption up to 6-7 servings/d (1 serving = 30 g) was not associated with higher risk of CHD, T2D, hypertension, or all-cause mortality. Moreover, total grain intake was not associated with risk of CVD, CHD, stroke, or cancer, but was associated with lower risk of all-cause mortality. Consequently, the recommendation to reduce refined grain intake based on results from studies linking a Western dietary pattern to numerous adverse health outcomes is contrary to a substantial body of published scientific evidence. Future research needs to better define refined grain intake to distinguish between staple grain foods and indulgent grain foods, and to better design randomized controlled trials to resolve discrepancies between results from observational studies and such trials with regard to determining the benefits of whole grains compared with refined grains.

A Western dietary pattern is prospectively associated with cardio-metabolic traits and incidence of the metabolic syndrome

The aim of this study was to derive dietary patterns associated with cardio-metabolic traits and to examine whether these predict prospective changes in these traits and incidence of the metabolic syndrome (iMetS). Subjects from the Malmö Diet and Cancer Study cardiovascular cohort without cardio-metabolic disease and related drug treatments at baseline (n 4071; aged 45-67 years, 40 % men) were included. We applied reduced rank regression on thirty-eight foods to derive patterns that explain variation in response variables measured at baseline (waist circumference, TAG, HDL- and LDL-cholesterol, systolic and diastolic blood pressure, fasting glucose and insulin). Patterns were examined in relation to change in cardio-metabolic traits and iMetS in subjects who were re-examined after 16·7 years (n 2704). Two dietary patterns ('Western' and 'Drinker') were retained and explained 3·2 % of the variation in response variables. The 'Western' dietary pattern was inversely associated with HDL-cholesterol and positively with all other response variables (both at baseline and follow-up), but there was no association with LDL at follow-up. After adjustment for potential confounders, the 'Western' dietary pattern was associated with higher risk of iMetS (hazard ratio Q4 v. Q1: 1·47; 95 % CI 1·23, 1·77; P trend=1·5×10-5). The 'Drinker' dietary pattern primarily explained variation in HDL and was not associated with iMetS. In conclusion, this study supports current food-based dietary guidelines suggesting that a 'Western' dietary pattern with high intakes of sugar-sweetened beverages and red and processed meats and low intakes of wine, cheese, vegetables and high-fibre foods is associated with detrimental effects on cardio-metabolic health.

Dairy product consumption is associated with pre-diabetes and newly diagnosed type 2 diabetes in the Lifelines Cohort Study

Previous studies show associations between dairy product consumption and type 2 diabetes, but only a few studies conducted detailed analyses for a variety of dairy subgroups. Therefore, we examined cross-sectional associations of a broad variety of dairy subgroups with pre-diabetes and newly diagnosed type 2 diabetes (ND-T2DM) among Dutch adults. In total, 112 086 adults without diabetes completed a semi-quantitative FFQ and donated blood. Pre-diabetes was defined as fasting plasma glucose (FPG) between 5·6 and 6·9 mmol/l or HbA1c% of 5·7-6·4 %. ND-T2DM was defined as FPG ≥7·0 mmol/l or HbA1c ≥6·5 %. Logistic regression analyses were conducted by 100 g or serving increase and dairy tertiles (T1ref), while adjusting for demographic, lifestyle and dietary covariates. Median dairy product intake was 324 (interquartile range 227) g/d; 25 549 (23 %) participants had pre-diabetes; and 1305 (1 %) had ND-T2DM. After full adjustment, inverse associations were observed of skimmed dairy (OR100 g 0·98; 95 % CI 0·97, 1·00), fermented dairy (OR100 g 0·98; 95 % CI 0·97, 0·99) and buttermilk (OR150 g 0·97; 95 % CI 0·94, 1·00) with pre-diabetes. Positive associations were observed for full-fat dairy (OR100 g 1·003; 95 % CI 1·01, 1·06), non-fermented dairy products (OR100 g 1·01; 95 % CI 1·00, 1·02) and custard (ORserving/150 g 1·13; 95 % CI 1·03, 1·24) with pre-diabetes. Moreover, full-fat dairy products (ORT3 1·16; 95 % CI 0·99, 1·35), non-fermented dairy products (OR100 g 1·05; 95 % CI 1·01, 1·09) and milk (ORserving/150 g 1·08; 95 % CI 1·02, 1·15) were positively associated with ND-T2DM. In conclusion, our data showed inverse associations of skimmed and fermented dairy products with pre-diabetes. Positive associations were observed for full-fat and non-fermented dairy products with pre-diabetes and ND-T2DM.

Effect of a high-egg diet on cardiometabolic risk factors in people with type 2 diabetes: the Diabetes and Egg (DIABEGG) Study-randomized weight-loss and follow-up phase

Background

Some country guidelines recommend that people with type 2 diabetes (T2D) limit their consumption of eggs and cholesterol. Our previously published 3-mo weight-maintenance study showed that a high-egg (≥12 eggs/wk) diet compared with a low-egg diet (<2 eggs/wk) did not have adverse effects on cardiometabolic risk factors in adults with T2D.

Objective

The current study follows the previously published 3-mo weight-maintenance study and assessed the effects of the high-egg compared with the low-egg diets as part of a 3-mo weight-loss period, followed by a 6-mo follow-up period for a total duration of 12 mo.

Design

Participants with prediabetes or T2D (n = 128) were prescribed a 3-mo daily energy restriction of 2.1 MJ and a macronutrient-matched diet and instructed on specific types and quantities of foods to be consumed, with an emphasis on replacing saturated fats with monounsaturated and polyunsaturated fats. Participants were followed up at the 9- and 12-mo visits.

Results

From 3 to 12 mo, the weight loss was similar (high-egg compared with low-egg diets: -3.1 ± 6.3 compared with -3.1 ± 5.2 kg; P = 0.48). There were no differences between groups in glycemia (plasma glucose, glycated hemoglobin, 1,5-anhydroglucitol), traditional serum lipids, markers of inflammation (high-sensitivity C-reactive protein, interleukin 6, soluble E-selectin), oxidative stress (F2-isoprostanes), or adiponectin from 3 to 12 mo or from 0 to 12 mo.

Conclusions

People with prediabetes or T2D who consumed a 3-mo high-egg weight-loss diet with a 6-mo follow-up exhibited no adverse changes in cardiometabolic markers compared with those who consumed a low-egg weight-loss diet. A healthy diet based on population guidelines and including more eggs than currently recommended by some countries may be safely consumed. This trial is registered at http://www.anzctr.org.au/ as ACTRN12612001266853.

Dietary protein intake and risk of type 2 diabetes: a dose-response meta-analysis of prospective studies

PURPOSE

The association between dietary protein intake and type 2 diabetes risk has been inconsistent in the previous epidemiological studies. We aimed to quantitatively assess whether dietary total, animal, and plant protein would be associated with type 2 diabetes risk.

METHODS

A comprehensive literature review was conducted to identify related articles by searching PubMed, Embase, Web of Science, and Wiley Online Library through 20th March 2018. Generalized least squares for trend estimation and restricted cubic spline regression model were applied in the dose-response analysis.

RESULTS

Eight publications with ten prospective cohorts of 34,221 type 2 diabetes cases were included. After adjustment of potential confounders, a 5% of energy increment from dietary total and animal protein intake was related to a 9% (1.04, 1.13; I² = 42.0%) and 12% (95% CI 1.08, 1.17; I² = 14.0%) higher risk of type 2 diabetes respectively. However, for plant protein, a significant U-shaped curve was observed with the most risk reduction at intake of about 6% of energy intake from plant protein intake (P_nonlinearity = 0.001). The results were robust in sensitivity analysis and no publication bias was detected.

CONCLUSIONS

These findings indicate that the consumption of protein particularly animal protein may be associated with an increased risk of type 2 diabetes.

Food patterns in relation to weight change and incidence of type 2 diabetes, coronary events and stroke in the Malmö Diet and Cancer cohort

Purpose

We examined if data-driven food-patterns associate with weight change, incidence of type 2 diabetes (T2D), coronary events (CE) and stroke.

Methods

The study included 20,487 individuals (61% women) from the Malmö Diet and Cancer cohort, 45–74 years, without diabetes and CVD at baseline (1991–1996) and who did not report dietary changes. Diet was measured with a modified diet history method. During 15 years follow-up, 2206 T2D, 1571 CE and 1332 stroke cases were identified. Data on weight change after 16.7 years were available in 2627 individuals.

Results

From principal component analysis, we identified six food-patterns which were similar in women and men. The first pattern, explaining 7% of the variance, was characterized by high intake of fibre-rich bread, breakfast cereals, fruits, vegetables, fish and low-fat yoghurt, and by low intake of low-fibre bread. This health conscious pattern was associated with lower T2D risk (HR comparing highest quintile with lowest: 0.75; 95% CI 0.61–0.92, 0.82; 95% CI 0.68–1.00 in women and men, respectively, P trends = 0.003, 0.01) and CE (HR 0.77; 95% CI 0.58–1.02, HR 0.83; 95% CI 0.68–1.01, P trends = 0.05, 0.07), and in men also with lower risk of ischemic stroke (HR 0.69; 95% CI 0.54–0.88; P trend = 0.001) and less pronounced weight gain (0.93 kg/10 years, P trend = 0.03). A low-fat product pattern was associated with increased T2D risk in gender combined analyses (P trend = 0.03) and a pattern characterized by dressing and vegetables with lower CE risk in men (P trend = 0.02).

Conclusions

Our main finding was that a dietary pattern indicating health conscious food choices was associated with lower risk of cardiometabolic diseases in both genders.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1727-9) contains supplementary material, which is available to authorized users.

Effects of supplemented isoenergetic diets varying in cereal fiber and protein content on the bile acid metabolic signature and relation to insulin resistance

Bile acids (BA) are potent metabolic regulators influenced by diet. We studied effects of isoenergetic increases in the dietary protein and cereal-fiber contents on circulating BA and insulin resistance (IR) in overweight and obese adults. Randomized controlled nutritional intervention (18 weeks) in 72 non-diabetic participants (overweight/obese: 29/43) with at least one further metabolic risk factor. Participants were group-matched and allocated to four isoenergetic supplemented diets: control; high cereal fiber (HCF); high-protein (HP); or moderately increased cereal fiber and protein (MIX). Whole-body IR and insulin-mediated suppression of hepatic endogenous glucose production were measured using euglycaemic–hyperinsulinemic clamps with [6-6²H₂] glucose infusion. Circulating BA, metabolic biomarkers, and IR were measured at 0, 6, and 18 weeks. Under isoenergetic conditions, HP-intake worsened IR in obese participants after 6 weeks (M-value: 3.77 ± 0.58 vs. 3.07 ± 0.44 mg/kg/min, p = 0.038), with partial improvement back to baseline levels after 18 weeks (3.25 ± 0.45 mg/kg/min, p = 0.089). No deleterious effects of HP-intake on IR were observed in overweight participants. HCF-diet improved IR in overweight participants after 6 weeks (M-value 4.25 ± 0.35 vs. 4.81 ± 0.31 mg/kg/min, p = 0.016), but did not influence IR in obese participants. Control and MIX diets did not influence IR. HP-induced, but not HCF-induced changes in IR strongly correlated with changes of BA profiles. MIX-diet significantly increased most BA at 18 weeks in obese, but not in overweight participants. BA remained unchanged in controls. Pooled BA concentrations correlated with fasting fibroblast growth factor-19 (FGF-19) plasma levels (r = 0.37; p = 0.003). Higher milk protein intake was the only significant dietary predictor for raised total and primary BA in regression analyses (total BA, p = 0.017; primary BA, p = 0.011). Combined increased intake of dietary protein and cereal fibers markedly increased serum BA concentrations in obese, but not in overweight participants. Possible mechanisms explaining this effect may include compensatory increases of the BA pool in the insulin resistant, obese state; or defective BA transport.

Impact of Dietary Fiber Consumption on Insulin Resistance and the Prevention of Type 2 Diabetes

Large prospective cohort studies consistently show associations of a high dietary fiber intake (>25 g/d in women and >38 g/d in men) with a 20-30% reduced risk of developing type 2 diabetes (T2D), after correction for confounders. It is less well recognized that these effects appear to be mainly driven by high intakes of whole grains and insoluble cereal fibers, which typically are nonviscous and do not relevantly influence postprandial glucose responses [i.e., glycemic index (GI)] or are strongly fermented by the gut microbiota in the colon. In contrast, a dietary focus on soluble, viscous, gel-forming, more readily fermentable fiber intakes derived from fruit and certain vegetables yields mixed results and generally does not appear to reduce T2D risk. Although disentangling types of fiber-rich foods and separating these from possible effects related to the GI is an obvious challenge, the common conclusion that key metabolic effects of high-fiber intake are explained by mechanisms that should mainly apply to the soluble, viscous type can be challenged. More recently, studies in humans and animal models focused on gaining mechanistic insights into why especially high-cereal-fiber (HCF) diets appear to improve insulin resistance (IR) and diabetes risk. Although effects of HCF diets on weight loss are only moderate and comparable to other types of dietary fibers, possible novel mechanisms have emerged, which include the prevention of the absorption of dietary protein and modulation of the amino acid metabolic signature. Here we provide an update of our previous review from 2008, with a focus on mechanistic insights of how HCF diets may improve IR and the risk of developing T2D.

Dietary Protein Consumption and the Risk of Type 2 Diabetes: A Systematic Review and Meta-Analysis of Cohort Studies

Recently, some studies have focused on the relationship between dietary protein intake and the risk of type 2 diabetes mellitus (T2DM), but the conclusions have been inconsistent. Therefore, in this paper, a systematic review and meta-analysis of cohort studies regarding protein consumption and T2DM risk are conducted in order to present the association between them. We searched the PubMed and Embase databases for cohort studies on dietary protein, high-protein food consumption and risk of T2DM, up to July 2017. A summary of relative risks was compiled by the fixed-effect model or random-effect model. Eleven cohort studies regarded protein intake and T2DM (52,637 cases among 483,174 participants). The summary RR and 95% CI (Confidence Interval) of T2DM was 1.12 (1.08–1.17) in all subjects, 1.13 (1.04–1.24) in men, and 1.09 (1.04–1.15) in women for total protein; 1.14 (1.09–1.19) in all subjects, 1.23 (1.09–1.38) in men, and 1.11 (1.03–1.19) in women for animal protein; 0.96 (0.88–1.06) in all subjects, 0.98 (0.72–1.34) in men, and 0.92 (0.86–0.98) in women for plant protein. We also compared the association between different food sources of protein and the risk of T2DM. The summary RR (Relative Risk) and 95% CI of T2DM was 1.22 (1.09–1.36) for red meat, 1.39 (1.29–1.49) for processed meat, 1.03 (0.89–1.17) for fish, 1.03 (0.64–1.67) for egg, 0.89 (0.84–0.94) for total dairy products, 0.87 (0.78–0.96) for whole milk, 0.83 (0.70–0.98) for yogurt, 0.74 (0.59–0.93) in women for soy. This meta-analysis shows that total protein and animal protein could increase the risk of T2DM in both males and females, and plant protein decreases the risk of T2DM in females. The association between high-protein food types and T2DM are also different. Red meat and processed meat are risk factors of T2DM, and soy, dairy and dairy products are the protective factors of T2DM. Egg and fish intake are not associated with a decreased risk of T2DM. This research indicates the type of dietary protein and food sources of protein that should be considered for the prevention of diabetes.

Branched-chain amino acid, meat intake and risk of type 2 diabetes in the Women's Health Initiative

Knowledge regarding association of dietary branched-chain amino acid (BCAA) and type 2 diabetes (T2D), and the contribution of BCAA from meat to the risk of T2D are scarce. We evaluated associations between dietary BCAA intake, meat intake, interaction between BCAA and meat intake and risk of T2D. Data analyses were performed for 74 155 participants aged 50-79 years at baseline from the Women's Health Initiative for up to 15 years of follow-up. We excluded from analysis participants with treated T2D, and factors potentially associated with T2D or missing covariate data. The BCAA and total meat intake was estimated from FFQ. Using Cox proportional hazards models, we assessed the relationship between BCAA intake, meat intake, and T2D, adjusting for confounders. A 20 % increment in total BCAA intake (g/d and %energy) was associated with a 7 % higher risk for T2D (hazard ratio (HR) 1·07; 95 % CI 1·05, 1·09). For total meat intake, a 20 % increment was associated with a 4 % higher risk of T2D (HR 1·04; 95 % CI 1·03, 1·05). The associations between BCAA intake and T2D were attenuated but remained significant after adjustment for total meat intake. These relations did not materially differ with or without adjustment for BMI. Our results suggest that dietary BCAA and meat intake are positively associated with T2D among postmenopausal women. The association of BCAA and diabetes risk was attenuated but remained positive after adjustment for meat intake suggesting that BCAA intake in part but not in full is contributing to the association of meat with T2D risk.

Intake of different dietary proteins and risk of type 2 diabetes in men: the Kuopio Ischaemic Heart Disease Risk Factor Study

The roles of different dietary proteins in the aetiology of type 2 diabetes (T2D) remain unclear. We investigated the associations of dietary proteins with the risk of incident T2D in Finnish men from the prospective Kuopio Ischaemic Heart Disease Risk Factor Study. The study included 2332 men aged 42–60 years at the baseline examinations in 1984–1989. Protein intakes were calculated from 4-d dietary records. Incident T2D was determined by self-administered questionnaires, fasting blood glucose measurements, 2-h oral glucose tolerance tests, and with national registers. The multivariable-adjusted risk of T2D on the basis of protein intakes was compared by the Cox proportional hazard ratios (HR). During the mean follow-up of 19·3 years, 432 incident T2D cases were identified. Total, animal, meat or dairy product protein intakes were not associated with risk of T2D when the potential confounders were accounted for. Plant (multivariable-adjusted extreme-quartile HR 0·65; 95 % CI 0·42, 1·00; Ptrend 0·04) and egg (HR 0·67; 95 % CI 0·44, 1·00; Ptrend 0·03) protein intakes were associated with a decreased risk of T2D. Adjustments for BMI, plasma glucose and serum insulin slightly attenuated associations. Replacing 1 % energy from carbohydrates with energy from protein was associated with a 5 % (95 % CI 0, 11) increased risk of T2D, but adjustment for fibre intake attenuated the association. Replacing 1 % of energy from animal protein with energy from plant protein was associated with 18 % (95 % CI 0, 32) decreased risk of T2D. This association remained after adjusting for BMI. In conclusion, favouring plant and egg proteins appeared to be beneficial in preventing T2D.