Eat more fruits and vegetables
Stroke is a leading cause of death and disability globally. Preventing stroke with better lifestyle choices has the potential to greatly reduce the incidence of stroke over time. The Working Group for Nutrition and Stroke in Italy conducted a systematic review of meta-analyses that evaluated risk of death from stroke in relation to dietary factors. Data from 87 meta-analyses (mainly prospective studies) provided evidence for primary prevention for stroke, including total stroke and ischemic and hemorrhagic sub-types. Food groups that received strong recommendations in favor of increased intake included fruits and vegetables, fish, milk and dairy products (especially the low-fat versions), coffee and tea, and chocolate. Food groups that received strong recommendations in favor of decreased intake included meat, processed meat and sweetened beverages. In addition, the Mediterranean and DASH dietary patterns received strong positive recommendations. This systematic review reprised typical recommendations for healthy eating to reduce the risk of other chronic diseases.
Meat might not matter
A 2016 report from the EPIC-Oxford study did not show a significant link between vegetarianism and death due to stroke. A 2019 update of the EPIC-Oxford study confirmed the previous report. The new results for 48,188 participants showed that vegetarians has a 20 percent higher risk of having a stroke compared to meat eaters over an average follow-up of 14 years. For every 100 persons over a 10-year period, the vegetarians would have three more cases of stroke than the meat eaters. Thus, the absolute difference in stroke risk for vegetarians was small relative to meat eaters. It’s worth considering that this same study found that vegetarians and fish eaters had a 13 percent lower risk of ischemic heart disease (caused by a blood clot the heart). Other research shows that hypertension accounts for the highest fraction of risk of stroke. Yet in the EPIC-Oxford study, vegetarians had twice the incidence of hypertension than meat eaters. This study illustrates the potential pitfalls of ascribing “healthy” or “unhealthy” to any particular approach to eating.
Meat might matter
Some studies show that higher consumption of red meat and processed meat predict greater risk of stroke. A unique study from Taiwan provides confirmation. The study included 5,050 participants with an average age of 53 years in the Tzu Chi Health Study and 8,302 participants with an average of 49 years in the Tzu Chi Vegetarian Study. Many of the participants were Tzu Chi volunteers who go through at least two years of training, commit to volunteer for community services, and avoid alcohol and smoking. About 30 percent of the combined cohorts are full-time vegetarians. Compared to non-vegetarians in the Tzu Chi Health Study and the Tzu Chi Vegetarian Study, vegetarians had 49 and 48 percent lower risks, respectively, of developing any type of stroke during follow-up. For ischemic stroke (by far the most common type), the comparable reductions in risk were 74 and 59 percent. These results contrast with those of the EPIC-Oxford study above. One possible reason for the difference is much higher alcohol and allium vegetable (onions and their relatives) intake by the EPIC-Oxford participants. In addition, Taiwanese vegetarians don’t smoke, while some of the EPIC-Oxford participants smoke. Finally, Taiwanese vegetarians might embrace other healthy lifestyle choices, such as volunteering, than their non-vegetarians counterparts
Eat more fiber, fruits, vegetables, and dairy
Stroke come in two types, ischemic and hemorrhagic, with the former being far more common than the latter. Prospective studies suggest that increased intake of certain foods reduces or increases the risk of stroke. A recent study used dietary data from 418,329 participants with an average age of 51 years from 22 centers in 9 European countries to determine which foods predicted risk of both types of stroke over an average follow-up of 13 years. Increased intake of dietary fiber, fruit and vegetables, cheese, yogurt, and milk independently and significantly reduced the risk of ischemic stroke. Specifically, increasing daily intake of fiber by 10 grams or fruits and vegetables by 200 grams (for example, about 1 ½ cups of broccoli or 1 1/4 cups of apples) reduced risk by 23 and 13 percent, respectively. For dairy foods, increasing daily intake of cheese, yogurt, or milk by 200 grams (about ¾ of a cup) decreased risk by 13, 9, and 9 percent, respectively. For hemorrhagic stroke, each 20 gram increase in egg intake (about half of a small egg) predicted a significant 25 percent increase in risk. Boost you daily diet with more fiber, fruits, vegetables, and dairy products to help avoid stroke.
More recent evidence
Hundreds, if not thousands of studies have evaluated the effects of diet on the risk of stroke. A new umbrella review included 122 meta-analyses in an attempt to settle contradictions among meta-analyses of prospective studies. Moderate to high strength evidence suggested that higher intakes of fruits and vegetables predicted significantly lower risk of total stroke, ischemic stroke, and hemorrhagic stroke. Higher intakes of red meat, particularly processed red meat, predicted significantly higher risk of total stroke, ischemic stroke, and hemorrhagic stroke. Lower quality evidence showed that increased intake of fish, nuts, peanuts, milk, chocolate, coffee, and tea predicted significantly lower risk of total stroke. These same foods plus whole grains predicted significantly lower risk of ischemic stroke. Lower quality evidence showed that increased intake of fruits, vegetables, fish, dairy products, chocolate, and tea predicted significantly lower risk of hemorrhagic stroke. With respect to individual nutrients, low-quality evidence suggested that increased intake of total fiber, vitamin C, folate, beta-carotene, lycopene, magnesium, and flavonoids predicted lower risk of total stroke. Increased intake of sodium predicted higher risk. The oft-repeated to eat more fruits and vegetables seems relevant to reducing your risk of stroke.
What to eat?
You probably already knew that dietary research frequently yields confusing or even contradictory findings. Don’t take the results of a single (or even many studies) as gospel. Some studies are poorly designed and/or conducted. Dietary studies, in particular, suffer from inherent problems that are difficult or impossible to remedy adequately. My take on the above studies: My current emphasis on eating lots of fruits (but not fruit juices) and vegetables, whole grains, nuts, and moderate amounts of low- or non-fat milk and yogurt probably reduce my risk of stroke. This way of eating also likely improves my metabolic health and reduces my risk of type 2 diabetes and dementia.