Alice Stanton

The world, in 2024, faces both climate and biodiversity crises, and the food system does contribute significantly to these crises. For some, the solution is simple - intakes of animal source foods (ASFs) should be considerably reduced, and consumption of plant-source foods (PSFs) should be greatly increased. Advocates for such a dietary transformation express confidence that plant-based diets will not only benefit planetary health, but will provide nutrient adequacy for all, and will also result in considerable protection from chronic non-communicable diseases (NCDs). However, as described in this perspective, the dramatic reductions in ASFs, entailed by many plant-based diets, will worsen already prevalent micronutrient and protein deficiencies. The protections provided by plant-based diets against NCDs appear to be more strongly associated with reduced intakes of calories and salt, and increased intakes of fruit, vegetables, nuts and whole grains, rather than with reduced intakes of ASFs. Any possible absolute adverse effects of red and processed meat consumption on NCDs are very small and uncertain. Other ASFs either appear to have no impact on NCDs (poultry meat and eggs), or are associated with protections against obesity, cardiovascular events, brain disorders and some cancers (seafood and dairy). Rigorous randomized controlled trials of all newly proposed environmentally-protective plant-based diets are required, so as to provide clear-cut evidence of micronutrient and protein adequacy, with or without, supplementation, fortification and/or biofortification. In the meantime, dietary guidelines should advise moderating excessive consumption, rather than substantially limiting or excluding ASFs from the human diet.

Many recent very influential reports, including those from the Global Burden of Disease (GBD) Risk Factor Collaborators, the EAT-Lancet Commission on Food, Planet, Health, and the Lancet Countdown on Health and Climate Change, have recommended dramatic reductions or total exclusion of animal-source foods, particularly ruminant products (red meat and dairy), from the human diet. They strongly suggest that these dietary shifts will not only benefit planetary health but also human health. However, as detailed in this perspective, there are grounds for considerable concern in regard to the quality and transparency of the input data, the validity of the assumptions, and the appropriateness of the statistical modelling, used in the calculation of the global health estimates, which underpin the claimed human health benefits. The lessor bioavailability of protein and key micronutrients from plant-source foods versus animal-source foods was not adequately recognised nor addressed in any of these reports. Furthermore, assessments of bias and certainty were either limited or absent. Despite many of these errors and limitations being publically acknowledged by the GBD and the EAT-Lancet authors, no corrections have been applied to the published papers. As a consequence, these reports continue to erroneously influence food policy decisions and international dietary guidelines, such as the World Wildlife Fund’s Livewell Diet, and the Nordic Nutrition Recommendations 2023.

Despite being a foundational part of human evolutionary diets and a source of high-quality protein and bioavailable micronutrients in a global context of nutrient insecurity (see elsewhere in this Special Issue; Leroy et al., 2023), the consumption of red and processed meats is nowadays increasingly discouraged by a vocal group of scientists and organizations. The rationale for this is based on a purported association of their intake with an increased risk of obesity and non-communicable diseases, such as myocardial infarction, stroke, diabetes, and particular cancers. As for most foods, one could assume that there may be compelling evidence for optimal intake levels, balancing the potential benefits and harms of meat as a human food. Such an optimum, however, is difficult to estimate, as the evidence is highly contextual and complex, or even conceptually incorrect to begin with.

Background: We have previously shown that tissue Doppler assessments of left ventricular (LV) diastolic function predict cardiac events in a hypertensive population over a period of 4 years (1). These out-performed traditional echocardiographic measures in a well-treated hypertensive population. Purpose: We aimed to test whether tissue Doppler assessment of LV diastolic function would predict cardiovascular (CV) mortality in the Hypertension Associated Cardiovascular Disease sub-study of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT). Methods: ASCOT was a multicentre randomised trial with a 2x2 factorial design (2). Inclusion criteria for the study included hypertension and three other CV risk factors, including male sex and age over 55. Protocols, including for echocardiography, have been detailed previously (2, 3). This study comprised the 519 patients recruited to the St Mary's Hospital site of the ASCOT study, who were followed for 19 years with mortality flagged by the Office for National Statistics. We have used all reported deaths on or before 31st January 2019. CV deaths include deaths due to coronary heart disease (CHD), stroke and other CV causes. Echocardiography was performed one year after blood pressure control. mean tissue Doppler E' was calculated as the average of septal, lateral and inferior wall measurements over three cycles. The ratio of the transmitral Doppler E wave velocity and the composite mean of E' was used to calculate E/E' ratio. Statistical analysis was performed using Python including multivariable Cox proportional hazards regression. A two-sided P-value <0.05 was considered statistically significant. Results: After a median of 19 years, 317 patients survived (mean age at baseline 60.7y, 38 female) and 202 did not (mean age 68.1y, 30 female). Twenty-three deaths were due to CHD, 11 were due to stroke, 27 were due to other CV causes, and 76 were due to cancer. Baseline characteristics were not significantly different between those who survived to follow up and those who did not. Unadjusted analysis showed a strong association between CV mortality and E' (HR=0.74, p<0.005) and E/E' (HR=1.18, p<0.005) (Table 1). The association between CV mortality and E' was attenuated slightly but persisted after adjusting for age and sex (HR=0.83, p=0.02) and after adjusting for age, sex and systolic BP (HR=0.83, p=0.03). The association between CV mortality and E/E' was attenuated but persisted after adjusting for age and sex (HR=1.12, p=0.01) and after adjusting for age, sex and systolic BP (HR=1.11, p=0.04). There was a weak association between all-cause mortality and both E/E' and E', which was null after adjusting for age and sex. Figure 1 shows unadjusted Kaplan Meier survival curves for E'. Conclusions: Tissue Doppler E' velocity and E/E' predicted 19-year cardiovascular mortality in a hypertensive population independent of age, sex and systolic blood pressure. Funding Acknowledgement: Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The HACVD substudy was supported by an investigational grant by Pfizer International, New York, NY, USA. The principal funding source for ASCOT was Pfizer, New York, NY, USA, additional funding was also provided by Servier Research Group, Paris, France, and Leo Laboratories, Copenhagen, Denmark.

Diets low in seafood omega-3 polyunsaturated fatty acids (PUFAs) are very prevalent. Such diets have recently been ranked as the sixth most important dietary risk factor—1.5 million deaths and 33 million disability-adjusted life-years worldwide are attributable to this deficiency. Wild oily fish stocks are insufficient to feed the world’s population, and levels of eicosapentaenoic acid and docosahexaenoic acid (DHA) in farmed fish have more than halved in the last 20 years. Here we report on a double-blinded, controlled trial, where 161 healthy normotensive adults were randomly allocated to eat at least three portions/week of omega-3-PUFA enriched (or control) chicken-meat, and to eat at least three omega-3-PUFA enriched (or control) eggs/week, for 6 months. We show that regular consumption of omega-3-PUFA enriched chicken-meat and eggs significantly increased the primary outcome, the red cell omega-3 index (mean difference [98.75% confidence interval] from the group that ate both control foods, 1.7% [0.7, 2.6]). Numbers of subjects with a very high-risk omega-3 index (index < 4%) were more than halved amongst the group that ate both enriched foods. Furthermore, eating the enriched foods resulted in clinically relevant reductions in diastolic blood pressure (− 3.1 mmHg [− 5.8, − 0.3]). We conclude that chicken-meat and eggs, naturally enriched with algae-sourced omega-3-PUFAs, may serve as alternative dietary sources of these essential micronutrients. Unlike many lifestyle interventions, long-term population health benefits do not depend on willingness of individuals to make long-lasting difficult dietary changes, but on the availability of a range of commonly eaten, relatively inexpensive, omega-3-PUFA enriched foods.

Introduction The association between long-chain omega-3 polyunsaturated fatty acids (PUFAs), brain health, cognitive function and mood has been the subject of intensive research. Marine-derived omega-3 PUFAs, such as docosahexaenoic acid and eicosapentaenoic acid, are highly concentrated in neuronal membranes and affect brain function. Many studies have found that consumption of omega-3 PUFAs is associated with lower risk of cognitive or mood dysfunction. However, other studies have demonstrated no beneficial effects. There appears to be inconsistent findings from both epidemiological and randomised controlled trial (RCT) studies. The aim of this review is to compile the previous literature and establish the efficacy of omega-3 PUFAs in enhancing cognitive performance and mood in healthy adults. Methods and analysis Prospective cohort studies, RCTs, controlled clinical trials, controlled before and after studies, interrupted time series with a minimum of 3 months duration will be eligible for inclusion. Studies on healthy adults over the age of 18, where the intervention/exposure of interest is omega-3 PUFAs will be included. The outcomes of interest are cognition and mood. Studies will be eligible for inclusion if they measure changes in cognitive function or mood, or the risk of developing cognitive or mood disorders using validated tools and assessments. Relevant search terms and keywords will be used to generate a systematic search in Cochrane Library, MEDLINE, EMBASE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Scopus and the grey literature. Two independent reviewers will screen studies for eligibility. Risk of bias in cohort and non-randomised studies will be assessed using the ROBINS-I tool. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials will be used for RCTs. If there are sufficient data, a meta-analysis will be conducted. Ethics and dissemination This systematic review does not involve primary data collection and therefore formal ethical approval is not required. Results will be disseminated through peer reviewed publications, conference presentations and the popular press. PROSPERO registration number CRD42018080800.