Improving nutrition science begins with asking better questions.

A priority of nutrition science is to identify dietary determinants of health and disease to inform effective public health policies, guidelines, and clinical interventions. Yet, conflicting findings in synthesizing evidence from randomized trials and observational data has contributed to confusion and uncertainty. Often, heterogeneity can be explained by the fact that seemingly similar bodies of evidence are asking very different questions. Improving the alignment within and between research domains begins with investigators clearly defining their diet-disease questions; however, nutritional exposures are complex and often require a greater degree of specificity. First, dietary data are compositional, meaning a change in a food may imply a compensatory change of other foods. Second, dietary data are multidimensional; that is, the primary components (i.e., foods) are comprised of sub-components (e.g., nutrients), and sub-components can be present in multiple primary components. Third, because diet is a lifelong exposure, the composition of a study population's background diet has implications on the interpretation of the exposure and the transportability of effect estimates. Collectively clarifying these key aspects of inherently complex dietary exposures when conducting research will facilitate appropriate evidence synthesis, improve certainty of evidence, and improve the ability of these efforts to inform policy and decision-making.

Role of dietary fibres in cardiometabolic diseases.

PURPOSE OF REVIEW: This review highlights recent developments in understanding the role of dietary fibre and specific fibre types on risk and management of cardiometabolic disease with a focus on the causal pathways leading to cardiometabolic diseases, namely weight management, glycaemic control, and lipid levels, as well as the latest findings for cardiovascular disease outcomes such as coronary heart disease, stroke, and mortality. Evidence for mechanisms through gut microbiota are also briefly reviewed. RECENT FINDINGS: Dietary fibre intake is associated with improved weight management, the extent of which may depend on the subtype of dietary fibre. Overall dietary fibre intake reduces blood glucose and HbA1c, however soluble fibres may be particularly effective in reducing HbA1c, fasting blood glucose and blood lipids. Individual meta-analyses and umbrella reviews of observational studies on dietary fibre, as well as major fibre types, observed inverse associations with incident coronary heart disease, stroke, and mortality due to cardiovascular disease. As different types of fibres exerted different health benefits, fibre diversity (i.e. combinations of fibres) should be further investigated. SUMMARY: Dietary fibres improve both short-term and long-term cardiometabolic disease risk factors and outcomes, and thus should be on every menu.

The Association between the Substitution of Red Meat with Legumes and the Risk of Primary Liver Cancer in the UK Biobank: A Cohort Study.

Primary liver cancer is globally on the rise, partially due to poor diets and sedentary lifestyles. Shifting to more plant-based diets may lower the risk. We aimed to estimate the effect of replacing total red meat, unprocessed red meat and processed red meat with legumes on primary liver cancer in a free-living population. We analyzed data from 126,744 UK Biobank participants who completed ≥ two 24 h diet recalls. Baseline characteristics were collected from the initial assessment visit. Information on liver cancer diagnoses was collected via external linkage to inpatient hospital episodes or central cancer registries. Cox proportional hazards regression models were used to estimate the substitution of 15 g/day of legumes with 15 g/day of total red meat, unprocessed red meat or processed red meat on liver cancer risk, using the leave-one-out food substitution model. During a median follow-up time of 11.1 years, 173 participants developed liver cancer. In the fully adjusted models, no association was observed when substituting 15 g/day of legumes with total red meat (HR: 1.02 (95% CI 0.96-1.08)), unprocessed red meat (HR: 1.00 (95% CI 0.94-1.06)) or processed red meat (HR: 1.09 (95% CI 0.99-1.21)). Overall, little evidence of an association between replacing red meat with legumes and liver cancer was observed. Further research in other study populations with longer follow-up time is warranted.

A systematic evaluation of seven different scores representing the EAT-Lancet reference diet and mortality, stroke, and greenhouse gas emissions in three cohorts.

Different approaches have been used for translation of the EAT-Lancet reference diet into dietary scores that can be used to assess health and environmental impact. Our aim was to compare the different EAT-Lancet diet scores, and to estimate their associations with all-cause mortality, stroke incidence, and greenhouse gas emissions. We did a systematic review (PROSPERO, CRD42021286597) to identify different scores representing adherence to the EAT-Lancet reference diet. We then qualitatively compared the diet adherence scores, including their ability to group individuals according the EAT-Lancet reference diet recommendations, and quantitatively assessed the associations of the diet scores with health and environmental outcome data in three diverse cohorts: the Danish Diet, Cancer and Health Cohort (DCH; n=52 452), the Swedish Malmö Diet and Cancer Cohort (MDC; n=20 973), and the Mexican Teachers' Cohort (MTC; n=30 151). The DCH and MTC used food frequency questionnaires and the MDC used a modified diet history method to assess dietary intake, which we used to compute EAT-Lancet diet scores and evaluate the associations of scores with hazard of all-cause mortality and stroke. In the MDC, dietary greenhouse gas emission values were summarised for every participant, which we used to predict greenhouse gas emissions associated with varying diet adherence scores on each scoring system. In our review, seven diet scores were identified (Knuppel et al, 2019; Trijsburg et al, 2020; Cacau et al, 2021; Hanley-Cook et al, 2021; Kesse-Guyot et al, 2021; Stubbendorff et al, 2022; and Colizzi et al, 2023). Two of the seven scores (Stubbendorff and Colizzi) were among the most consistent in grouping participants according to the EAT-Lancet reference diet recommendations across cohorts, and higher scores (greater diet adherence) were associated with decreased risk of mortality (in the DCH and MDC), decreased risk of incident stroke (in the DCH and MDC for the Stubbendorff score; and in the DCH for the Colizzi score), and decreased predicted greenhouse gas emissions in the MDC. We conclude that the seven different scores representing the EAT-Lancet reference diet had differences in construction, interpretation, and relation to disease and climate-related outcomes. Two scores generally performed well in our evaluation. Future studies should carefully consider which diet score to use and preferably use multiple scores to assess the robustness of estimations, given that public health and environmental policy rely on these estimates.

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.

Adherence to the EAT-Lancet diet in midlife and development in weight or waist circumference after five years in a Danish cohort.

Purpose: The EAT-Lancet reference diet has been proposed as a healthy dietary pattern to reduce food-related climate impacts, but little is known regarding associations with bodyweight development. This study investigated adherence to the EAT-Lancet diet in midlife and development in weight and waist circumference (WC) after five years. Design: The Danish Diet, Cancer and Health cohort recruited participants in 1993-1997. At baseline, data on diet, lifestyle, and anthropometry were collected. Participants self-reported weight and WC five years later. In total, 44,194 participants were included in analyses of weight (43,678 for WC). Baseline adherence to the EAT-Lancet diet was scored 0-14 points. Multiple linear regression was used to estimate associations between the EAT-Lancet diet and development in weight and WC after five years. Poisson regression was used to estimate risk ratios (RR) of obesity (≥30 kg/m2) or elevated WC. Results: Adherence to the EAT-Lancet diet was not associated with follow-up weight, adjusting for baseline weight and confounders (11-14 vs 0-7 points ß: -0.08, 95% CI: -0.27, 0.11 kg), but was associated with lower follow-up WC adjusting for baseline WC and confounders (ß: -0.38, 95% CI: -0.69, -0.07 cm), and was associated with lower risk of obesity and elevated WC (RR 0.89, 95% CI: 0.82, 0.98, and 0.95, 95% CI: 0.93, 0.96, respectively). Conclusion: Adherence to the EAT-Lancet diet in midlife was associated with lower WC but not weight after five years follow up, taking baseline into account. Our findings suggest that greater adherence to the EAT-Lancet diet does not contribute to development of obesity.