Vegetarians, vegans and pescetarians have a lower risk of coronary heart disease (CHD), a recent study published in the BMJ found, but vegans and vegetarians, specifically, are also more at risk for stroke than meat-eaters.
Researchers from the University of Oxford conducted the study after tracking 48,188 people, with an average age of 45, for 18 years.
The participants – who were grouped by meat-eaters (24,428), pescetarians (7,506), and vegetarians, including vegans (16,254) – had no history of CHD or stroke.
After the 18-year study period, researchers reported 2,820 cases of CHD and 1,072 cases of stroke during the study period — “including 519 cases of ischaemic stroke (when a blood clot blocks the flow of blood and oxygen to the brain) and 300 cases of hemorrhagic stroke,” according to a press release regarding the findings.
After accounting for medical history, physical activity and smoking, among other factors that could influence the results, they determined pescetarians had a 13 percent lower risk of CHD, while vegetarians had a 22 percent lower risk.
“The difference may be at least partly due to lower BMI and lower rates of high blood pressure, high blood cholesterol and diabetes linked to these diets,” the authors concluded, according to the release.
That said, researchers also found vegetarians and vegans had a 20 percent higher risk of stroke than their meat-eating counterparts, which is “equivalent to three more cases of stroke per 1,000 people over 10 years, mainly due to a higher rate of hemorrhagic stroke.”
There was not a significantly higher rate of stroke for pescetarians.
Though an exact reason has not been established, those who follow vegetarian and vegan diets “had lower circulating cholesterol and levels of several nutrients than meat-eaters,” such as vitamin B12, they wrote of a possible cause.
“The higher relative risk of stroke among vegetarians is a new contribution to the body of evidence on the health effects of a vegetarian diet,” Mark Lawrence and Sarah McNaughton, professors at Deakin University in Australia, wrote in an editorial addressing the findings. They were not involved in the study.
The researchers warned that the study was observational, saying “the findings may not be widely applicable because they were mainly based on white Europeans,” per the release.
"It is based on results from just one study and the increase is modest relative to meat-eaters," Lawrence and McNaughton added.
"Relevance to vegetarians worldwide must also be considered," they said. "Participants were all from the U.K. where dietary patterns and other lifestyle behaviors are likely very different from those prevalent in low and middle-income countries where most of the world's vegetarians live."