By Reed Mangels, PhD, RD

A recently published study from the UK examined more than 48,000 vegans, vegetarians, fish eaters, and meat eaters and their risk of heart disease and stroke over an 18 year period. Because of the relatively small number of vegans, they were combined with lacto vegetarians and lacto-ovo vegetarians into a group called “vegetarians.” The vegetarians (including vegans) had a 22% lower risk of heart disease than the meat eaters; fish eaters had a 13% lower risk than the meat eaters. According to the study’s authors, these results suggest that if a group of 1000 meat eaters was compared to a group of 1000 vegetarians, over a 10 year period, there would be 10 fewer cases of heart disease in the vegetarians than in meat eaters.

In contrast, vegetarians (including vegans) had a higher risk of a kind of stroke called hemorrhagic stroke and of stroke overall than did meat eaters. This suggests that if a group of 1000 meat eaters was compared to a group of 1000 vegetarians, over a 10 year period, there would be 3 more cases of stroke in vegetarians than in meat eaters. There are two main types of stroke – ischemic and hemorrhagic. Ischemic strokes are more common (87% of all strokes) and are due to a blood clot blocking blood flow to the brain. Hemorrhagic strokes are less common and are caused by a weakened blood vessel rupturing and bleeding into the brain.

When vegans were examined separately from other vegetarians, vegans had a lower risk of heart disease than meat eaters but a higher risk for stroke although neither estimate was statistically significant, possibly due to the small number of cases in vegans.

This study’s results are similar to those of other studies which have reported a reduced risk of heart disease or of dying from heart disease in vegetarians including vegans. Up until now, studies of strokes in vegetarians have only looked at the risk of dying from stroke and found no significant difference of dying from stroke by diet group.

The study’s authors note that vegetarians and vegans in this study have lower blood levels of vitamin B12, vitamin D, and omega-3 fatty acids than do meat eaters and wonder if these differences could have contributed to the higher risk of stroke seen in vegetarians in this study.

We also note that there were only small differences in saturated fat and fiber intake between the vegetarian and meat eating groups. Additional research should be done using groups with larger differences in intakes of saturated fat and fiber.

If other large studies have similar results to this study, it will be important to identify dietary changes that vegetarians can make to reduce their risk of stroke without affecting their already reduced risk of heart disease. While we don’t know if lower blood levels of vitamin B12, vitamin D, and omega-3 fatty acids were related to the higher risk of stroke, we do know that having adequate amounts of these nutrients is important for overall health.

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:l4897.