Vegetarian, Vegan Diets Linked to Lower Heart Disease Risk, but Higher Risk of Stroke

Vegetarian and pescetarian diets could lower the risk of coronary heart disease, according to research. But vegetarians and vegans are also more likely to have strokes than meat eaters.

The study involved 48,188 people from the U.K. who were recruited between 1993 and 2001 when they had no history of cardiovascular disease. This umbrella term includes conditions which affect the blood vessels, including heart attacks and strokes. They answered questions about their diets at the start of the study, and again in around 2010.

Researchers used this information to split the participants into three groups: meat-eaters; fish-eaters (pescetarians); and vegetarians, including vegans.

When compared with meat-eaters, pescetarians and vegetarians were found to have a 13 percent and 22 percent lower chance of developing coronary heart disease, respectively.

However, vegetarians and vegans were found to have a 20 percent higher risk of experiencing stroke than meat-eaters. This was largely associated with hemorrhagic stroke: a relatively uncommon form of the condition where weakened vessels rupture and cause bleeding in the brain.

This is the first study to look at whether strokes are linked to vegetarian diets, according to the authors.

Study co-author Tammy Tong, a nutritional epidemiologist at the University of Oxford, told Newsweek that as the research was observational the team couldn't answer what underlies this link.

"There is some recent evidence that suggests while low levels of total or LDL cholesterol is protective against heart disease, very low levels might be linked to a slightly higher risk of haemorrhagic stroke, which is the subtype of stroke that was higher in the vegetarians in our study," she said.

"Vegetarian and vegan diets may also be naturally low in some nutrients, such as vitamin B12, which is available for vegetarians in some fortified foods and from supplements, but is otherwise only naturally available from animal sourced foods. Some research has suggested there may be a link between B12 deficiency and higher stroke risk, but the evidence is not conclusive."

Tong said more research is needed to determine the link of both cholesterol and individual nutrients like vitamin B12 with stroke risk. And as the study was based on the U.K. population and included mostly white European individuals, more research is needed to confirm whether the results are generalizable to people of other ethnicities or living in other regions of the world.

She highlighted that the team found a lower risk of coronary heart disease in both pescetarians and vegetarians and vegans, equivalent to six fewer cases of heart disease in the pescetarians and 10 fewer cases in the vegetarians, compared with meat-eaters, in every 1,000 people consuming these diets over 10 years. In contrast, there would be three more cases of stroke in the vegetarians than meat eaters over the same time period.

Speaking broadly on the current scientific consensus on the healthiest diet, Tong said: "There is good evidence that a number of healthy dietary patterns, including the Mediterranean diet, but also the Nordic diet or the DASH diet for example, is linked to lower risks of some chronic diseases.

Fruits, vegetables, whole grains, and legumes feature heavily in these diets, as well as low levels of red and processed meat, Tong said.

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Scientists investigated whether diets including and excluding meat are linked to coronary heart disease. This stock image of a couple eating lunch. Getty