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By Eric Neilson, MD
Dr. Neilson is Assistant Professor, Department of Clinical Foundations at Ross University School of Medicine, Barbados, West Indies
Dr. Neilson reports no financial relationships relevant to this field of study.
SYNOPSIS: A recent study revealed vegetarians have a 22% lower incidence of ischemic heart disease, but a 20% increased incidence of total stroke, mostly related to hemorrhagic stroke, when compared to meat eaters.
SOURCE: Tong TYN, Appleby PN, Bradbury KE, et al. Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: Results from the prospective EPIC-Oxford study. BMJ 2019;366:I4897.
Published dietary recommendations often are confusing, controversial, or contradictory. This is especially true for vegetarian diets and red meat consumption, wherein current recommendations vary widely. A journal recently published, with low-certainty evidence, a weak recommendation for adults to continue current processed and unprocessed red meat consumption.1 The World Health Organization’s International Agency for Research on Cancer lists processed meat in the Group 1, carcinogenic to humans, classification.2 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines strongly recommend (Class I, Level A evidence) a diet high in vegetables, fruits, and whole grains, including low-fat dairy, poultry, and fish, with limited red meat.3 Providing patients with clear, unambiguous dietary advice seems to be an impossible mission. Tong et al offered evidence that further complicates this conversation. These authors followed nearly 50,000 vegetarians, red meat eaters, and pescatarians for 18 years to monitor stroke and ischemic heart disease outcomes. Using proportional hazards regression models for associations between diet groups, results indicated that compared to a diet inclusive of red meat, a pescatarian or vegetarian diet is associated with a lower risk of ischemic heart disease. However, when compared to a diet including red meat, a vegetarian diet is associated with higher risks of total and hemorrhagic stroke. This risk reduction translates to four and 10 fewer incidents of ischemic heart disease per 1,000 persons over 10 years for pescatarians and vegetarians, respectively, compared to red meat eaters (predicted incidents per 1,000 population: 40.4 pescatarians and 36.2 vegetarians vs. 46.2 meat eaters; 95% confidence interval [CI] and P heterogeneity value < 0.001). Vegetarians experienced three more cases of total stoke per 1,000 persons over 10 years compared to red meat eaters (18.3 vs. 15.4; 95% CI and P heterogeneity value = 0.04). Data indicated there was no statistically significant increase in stroke incidence for pescatarians. Continued research on larger and more diverse groups of participants and considerations of the effects of specific nutrients associated with variations in diet (e.g., cholesterol, fatty acids, vitamin B12) are critical to determine the underlying mechanisms for the results found in this study. This nutritional study also was complicated by self-reporting, exclusion of high calorie intake, and changes in diet over time, which must be considered in future research. The study supports general ACC/AHA guidelines and indicates the need for physicians to talk with patients about the risks and benefits of individual dietary considerations.
Financial Disclosure: Internal Medicine Alert’s Physician Editor Stephen Brunton, MD, is a retained consultant for Abbott, Acadia, Allergan, AstraZeneca, Avadel, Boehringer Ingelheim, GlaxoSmithKline, Janssen, Mylan, and Salix; he serves on the speakers bureau of AstraZeneca, Boehringer Ingelheim, Janssen, Lilly, and Novo Nordisk. Peer Reviewer Gerald Roberts, MD; Editor Jonathan Springston; Editor Jason Schneider; Editorial Group Manager Leslie Coplin; and Accreditations Manager Amy M. Johnson, MSN, RN, CPN, report no financial relationships relevant to this field of study.