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Vegetarian diets are associated with decreased risk of heart disease, but increased risk of stroke. Getty Images
  • A new study looks at the benefits and drawbacks of avoiding meat and other animal products.
  • Researchers found that people who avoided meat may be more at risk for having a stroke.
  • However, people who eat meat are more likely to develop heart disease.

It’s commonly accepted that a plant-based diet will reduce the risk of heart disease — but recent research finds that it may put you at risk for another serious health issue: stroke.

Published in the UK-based BMJ, a new study looked at meat eaters, fish eaters, and vegetarians over an 18-year follow-up period.

“Vegetarian and vegan diets have become increasingly popular in recent years, partly due to the perceived health benefits, but also concerns about the environment and animal welfare,” lead researcher, Tammy Tong, PhD, told Healthline.

According to the findings, fish eaters and vegetarians had 13 percent and 22 percent lower rates of heart disease, respectively, compared to meat eaters. But the researchers also discovered something very surprising.

Vegetarians experienced a roughly 20 percent higher stroke risk than meat eaters, and it was mostly due to a higher rate of one particular type called hemorrhagic stroke.

“Hemorrhagic stroke is a type of stroke caused because of a rupture of a weakened blood vessel causing spillage of blood into the brain. Most common causes include uncontrolled high blood pressure, rupture of a brain aneurysm, or rupture of an abnormal blood vessel in the brain,” said Dr. Ishwara Sankara, neurointensivist and Texas Health Fort Worth medical staff with Neurocritical Care Associates of Fort Worth, a Texas Health Physicians Group practice.

Sankara explained that these types of strokes can often cause more damage and be more deadly than ischemic strokes caused by blood clots.

This study was based on the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford) Study and included information on 48,188 people in their 40s with no history of coronary heart disease or stroke.

They were divided into meat eaters, pescatarians (fish eaters), and vegetarians and vegans.

According to an accompanying editorial published along with this study, it was “the ideal study design for examining long-term effects of dietary patterns on health. The authors paid particular attention to adjusting for sociodemographic and lifestyle confounders and to applying rigorous statistical methods.”

While previous research has associated vegetarian eating with a reduced risk of coronary heart disease compared to people who eat meat, little has been reported on the difference in stroke risk.

As the health, environmental, and ethical concerns associated with meat grow in importance, more people than ever have been turning to vegetarian or vegan diets.

“However, the full extent of the potential health benefits and hazards of these diets is not well understood,” said Tong. “Some recent evidence has suggested that very low cholesterol levels might be linked to a higher risk of hemorrhagic stroke, although low cholesterol level is protective against heart disease.”

“But, in absolute numbers, the lower risk of coronary heart disease does exceed the higher risk of stroke in the vegetarians,” she said. “The findings are also currently based on a single study, so more research is needed to examine whether the findings are generalizable to other populations.”

Tong suggests the increased stroke risk associated with a vegetarian diet may reflect low blood levels of total cholesterol or a low intake of certain essential nutrients.

“The higher rate of hemorrhagic and total stroke in the vegetarian/vegan group seems surprising. However, as the authors point out, these findings are not dissimilar to other research from Japan and China linking vegetarian diets with higher rates of stroke. They attribute this to a possible protective effect of some meat products,” said Dr. Jennifer H. Haythe, cardiologist at Columbia University Irving Medical Center.

Sankara emphasized that further research is needed to understand the reason for this increased risk.

“One thing that could contribute to this observation may be the fact that vegetarians and vegans are at a higher risk of developing vitamin B-12, vitamin D, and other nutrient deficiencies which could contribute to neurological illness,” Sankara said.

If the body has a nutrient deficiency it can lead to an increased risk for a variety of health issues.

“Nutrient deficiencies, especially vitamin deficiencies such as vitamin B-12, and other B vitamins like folic acid (B-9) and B-6, can increase the risk of stroke,” he said.

“Vitamin D deficiency can also increase the risk of stroke. It’s imperative that vegetarians discuss with their primary care physician, be screened for such deficiencies, and be appropriately treated with vitamin supplements as needed,” he added.

The brain is an extremely fatty organ.

Roughly 60 percent of a human brain is fat, 20 percent of which is a fat with extraordinary health properties. It’s an omega-3 fatty acid called docosahexaenoic acid (DHA).

DHA’s critical functions include:

  • the formation of myelin to insulate our nerves and neurons
  • maintaining the integrity of the blood-brain barrier
  • playing a critical role in the development of the brain’s cortex, where we do all our most complex thinking

Without DHA, the complicated connections needed for mental focus and problem-solving ability won’t form properly, and plant foods don’t have it.

For people who follow vegan or vegetarian diets, it’s important to know this.

The omega-3 fatty acid in plant foods like kidney beans or flax is called alpha-linolenic acid (ALA). ALA is very difficult for the human body to convert into DHA.

Recent research finds people eating a vegetarian or vegan diet have a reduced risk of coronary heart disease, but an increased risk of a particularly dangerous kind of stroke.

Experts say this could be because plant-based diets lack certain essential nutrients, but they caution more research is needed to confirm this association.

For optimal health and development, the human brain requires a fat called DHA that can only be found in meat. While plant foods do contain a substance called ALA that can be changed into DHA, very little of it can be converted in the body.