Research has shown that adequate folic acid intake can reduce blood levels of the amino acid homocysteine, which at high levels has been linked to increased risk of cardiovascular disease, and stroke in particular. If folic acid does reduce homocysteine levels, it would seem that eating folic acid-rich foods might help ward off cardiovascular disease and stroke. Research recently published in Stroke: Journal of the American Heart Association suggests that higher folic acid intakes do indeed reduce your risk of stroke.

About the study

Researchers from Tulane University in New Orleans and the National Institutes of Health analyzed data on 9764 men and women who had participated in the NHANES I Epidemiologic Follow-up Study (NHEFS). These people were between the ages of 25 and 74 when they entered the study between 1971 and 1975 and had no history of heart attack, heart failure or stroke before entering the study.

At the start of the study, all participants underwent a physical exam. In addition, trained interviewers used structured questionnaires to interview participants about their medical history, and dietary and lifestyle habits, such as smoking, alcohol intake, and exercise. The researchers used a nutrient database to determine how much folic acid was in the food participants reported eating.

Follow-up interviews were conducted in 1982, 1984, 1986, 1987, and 1992. In addition, researchers obtained death certificates for people who had died and medical records for those who reported developing cardiovascular disease or having a stroke.

After an average of 19 years of follow-up, researchers compared the folic acid intakes of people who developed cardiovascular disease or had a stroke with those who did not.

The findings

Participants who consumed at least 300 micrograms (mcg) of folic acid per day were 20% less likely to have a stroke and 13% less likely to develop cardiovascular disease than their counterparts who consumed less than 136 mcg per day.

In calculating these statistics, the researchers accounted for the effects of other risk factors for cardiovascular disease and stroke, such as age, body weight, smoking, exercise, cholesterol levels, blood pressure, diabetes, and dietary fat.

Although these results are interesting, there are some limitations to this study.

Participants were only asked to recall what they had eaten in the last 24 hours. Although this increases the accuracy of the participants’ recall, it assumes that what they ate in the past 24 hours is representative of their dietary habits overall. Because dietary folic acid was measured only once at the start of the study, these findings do not account for any changes in folic acid intake that may have occurred during the 19-year follow-up period. And because the researchers did not collect information on use of folic acid supplements, it’s unclear what role supplements may have played in these results. In addition, the use of the nutrient database to estimate the folic acid content of foods may have overestimated the folic acid content of some foods because of changes in folic acid content over time.

How does this affect you?

We already know that folic acid is important for women of childbearing age, as it definitely plays a role in the prevention of some birth defects. But in addition to helping prevent birth defects, this study suggests that folic acid can help you ward off cardiovascular disease, and stroke in particular. Although previous research has indicated that folic acid may reduce the risk of stroke, this is the first study to find the benefit among a large group of people followed for nearly 20 years.

What foods contain folic acid? Plenty! Because research has shown that folic acid intake in the early days of pregnancy helps prevent birth defects, the federal government has mandated that a number of grain products be fortified with folic acid, including:

  • Rice
  • Pasta
  • Breakfast cereals
  • Most enriched breads
  • Flour
  • Cornmeal

Foods that naturally contain folic acid include:

  • Leafy dark green vegetables
  • Legumes (dried beans and peas)
  • Citrus fruits and juices
  • Most berries