High dietary folate may decrease the incidence of stroke, according to a 20-year study reported in a recent edition of Stroke: Journal of the American Heart Association.

Researchers found that people who consumed at least 300 micrograms (mcg) of folate per day had a 20% lower risk of stroke and a 13% lower risk of cardiovascular disease than those consuming less than 136 mcg of folate per day. The findings accounted for other heart disease risk factors such as cholesterol, blood pressure, smoking and obesity.

“Our data support the existing recommendation to consume 400 mcg of folate per day,” says the study’s lead author Lydia A. Bazzano, Ph.D., a research fellow at Tulane School of Public Health and Tropical Medicine in New Orleans.

For consumers, Bazzano says the results of this study mean that it is likely that dietary intake of folate can affect the risk of stroke.

“Therefore, people should be aware of the amount of folate in their diets,” she says.

“For doctors, this study would suggest that screening patients’ dietary folate intake and promoting the recommended level may decrease patients’ risk of stroke.”

Folate is thought to have beneficial effects on the cardiovascular system by decreasing levels of homocysteine, an amino acid that is linked to a higher risk of atherosclerosis. Atherosclerosis is the disease process that underlies heart disease and stroke.

Folate can reduce homocysteine, but this new study looks at the direct effect of folate on cardiovascular disease risk, according to Bazzano. Researchers looked at participants in the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study (NHEFS) to examine the relationship of dietary folate intake to the risk of cardiovascular disease.

Study participants included 9,764 men and women in the US, ages 25 to 74 years. They did not have cardiovascular disease when the study started. In the original study, researchers asked participants to recall the food they had eaten during the last 24 hours. Specific dietary intake of folate was not available in the first database, but researchers later matched the recorded foods and portions to foods listed in a database to estimate the amount of folate ingested by patients in a 24-hour period.

According to the study, follow-up data were collected between 1982 and 1984, and in 1986, 1987, and 1992. Each follow-up examination included performing an in-depth interview; obtaining hospital and nursing home records, including pathology reports and electrocardiograms; and, for those who died during the study, acquiring a death certificate. The researchers recorded incidences of stroke and cardiovascular disease that occurred during follow-up.
The results showed participants’ median folate intake was 203.7 mcg per day.

Folate is a B-vitamin found in citrus fruits; tomatoes; leafy green vegetables such as spinach and romaine lettuce; pinto, navy, and kidney beans; and grain products. Since January 1998, wheat flour has been fortified with folic acid, the synthetic form of folate, to add an estimated 100 mcg per day to the average diet.