"Improving diet and lifestyle is critical for heart and stroke risk reduction in the general population," lead researcher Yan Qu, MD, said. "In particular, a diet rich in fruits and vegetables is highly recommended because it meets micronutrient and macronutrient and fiber requirements without adding substantially to overall energy requirements."

Stroke, which occurs when the blood flow to any part of the brain is obstructed due to a clot or a ruptured blood vessel, is the fourth-leading cause of death in the United States, and one of the major causes of disability (due to brain damage). In China, where the study was conducted, stroke is the foremost cause of death, responsible for 1.7 million fatalities in 2010

Less than half a pound daily cuts risk by a third

While many studies have previously looked into the relationship between diet and stroke risk, results have not been consistent. In order to help resolve this inconsistency, the researchers conducted a meta-analysis of 20 prior studies published over the last 19 years. The analysis included data from 16,981 strokes among 760,629 participants. Six of the studies had been conducted in the United States, eight in Europe and six in China and Japan.

The researchers found that people who ate the most fruits and vegetables were 21 percent less likely to experience a stroke than people who ate the least. Indeed, every extra 200 grams (7 ounces) of daily fruit intake reduced stroke risk by 32 percent, while every extra 200 grams of vegetable intake reduced the risk by 11 percent. The greatest benefit came from consumption of apples, citrus fruits, pears and leafy vegetables.

"The effect of other types of fruit and vegetables on stroke risk still needs to be confirmed," Qu said.

The findings remained significant, even after the researchers adjusted for potential confounding factors including alcohol consumption, blood pressure, body mass index, cholesterol levels, physical activity and smoking. The findings were the same in both men and women, and in participants both younger and older than 55. Fruit and vegetable consumption was found to prevent stroke caused both by blood clots and by bleeding.
 

Follow dietary recommendations

The findings add further weight to existing dietary recommendations from groups such as the Centers for Disease Control and Prevention and the American Heart Association, which encourage people to consume five servings of fruits and vegetables daily.

Unfortunately, the researchers noted, fruit and vegetable consumption tends to be low globally, particularly in low- to middle-income countries. Indeed, the World Health Organization has estimated that, if every person ate 600 grams (20 ounces) of fruits and vegetables per day, the global stroke rate could drop by 19 percent.

"The findings are consistent with the current knowledge that increasing consumption of fruits and vegetables should be encouraged to prevent stroke," Qu said.

What the study did not do was explain why fruits and vegetables lower the risk of stroke. The benefit might come from specific nutrients contained in particular foods; from the fact that diets high in fruits and vegetables improve overall health, reducing stroke risk factors such as blood pressure, cholesterol and weight; or from some combination of factors.

The study found that people with the lowest stroke risk not only ate lots of fruits and vegetables but also controlled other risk factors such as weight and smoking