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

There is limited evidence on the long-term health outcomes associated with vegetarian and vegan diets, including risks of ischaemic heart disease (IHD) and stroke, which are the top two causes of death worldwide. We examined this using data from the EPIC-Oxford study. We analysed data on 48 188 participants with no history of cardiovascular disease, who were classified into three distinct diet groups: meat eaters (participants who consumed meat, regardless of whether they consumed fish, dairy, or eggs, n=24 428), fish eaters (consumed fish but no meat, n=7506), and vegetarians including vegans (n=16 254), based on dietary information collected at recruitment (1993-2001), and subsequently around 2010 (n=28 364).

Over 18 years of follow-up, 2820 cases of IHD and 1072 cases of total stroke (519 of ischaemic stroke and 300 of haemorrhagic stroke) were recorded. Compared with meat eaters, and after adjusting for socio-demographic and lifestyle confounders, the fish eaters and vegetarians had 13% (95% confidence interval 1 to 23%) and 22% (13 to 30%) lower rates of IHD, respectively, equivalent to 10 fewer cases (6.7 to 13.1 fewer) in the vegetarians per 1000 population over 10 years. In contrast, vegetarians had 20% higher rates of total stroke (2 to 40%) compared with meat eaters, equivalent to 3 more (0.8 to 5.4) cases per 1000 population over 10 years, mostly due to a higher rate of haemorrhagic stroke.

After adjusting for sociodemographic and lifestyle confounders, fish eaters and vegetarians had 13% (hazard ratio 0.87, 95% confidence interval 0.77 to 0.99) and 22% (0.78, 0.70 to 0.87) lower rates of ischaemic heart disease than meat eaters, respectively (P<0.001 for heterogeneity). This difference was equivalent to 10 fewer cases of ischaemic heart disease (95% confidence interval 6.7 to 13.1 fewer) in vegetarians than in meat eaters per 1000 population over 10 years. The associations for ischaemic heart disease were partly attenuated after adjustment for self reported high blood cholesterol, high blood pressure, diabetes, and body mass index (hazard ratio 0.90, 95% confidence interval 0.81 to 1.00 in vegetarians with all adjustments). By contrast, vegetarians had 20% higher rates of total stroke (hazard ratio 1.20, 95% confidence interval 1.02 to 1.40) than meat eaters, equivalent to three more cases of total stroke (95% confidence interval 0.8 to 5.4 more) per 1000 population over 10 years, mostly due to a higher rate of haemorrhagic stroke. The associations for stroke did not attenuate after further adjustment of disease risk factors.

Conclusions In this prospective cohort in the UK, fish eaters and vegetarians had lower rates of ischaemic heart disease than meat eaters, although vegetarians had higher rates of haemorrhagic and total stroke.