(2/25/98) - Eating about twice the recommended daily allowance (RDA) of folic acid and vitamin B6 may reduce women’s risk of heart disease, according to the 14-year Nurses' Health Study of more than 80,000 nurses. The finding supports the theory that homocysteine, an amino acid that these vitamins help diminish, may contribute to heart disease, researchers say.

Previous studies have shown that a high intake of folic acid and B₆ lowers homocysteine concentrations in the blood. The amino acid helps plaque to collect in the heart’s arteries, which can lead to a stroke or heart attack. Up to 40 percent of heart-disease patients have high concentrations of homocysteine, researchers say.

At the outset of the Nurses' Health Study, the women had no history of heart disease, cancer, high cholesterol, or diabetes. However, during the 14 years of follow-up, 939 of the nurses developed heart disease. These women tended to eat or take the least amount of folic acid and B₆ of all the study participants, Eric B. Rimm of the Harvard School of Public Health in Boston and his colleagues report in the February 4 Journal of the American Medical Association.

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Compared with others in the group, the women who got the largest amounts of the vitamins faced about half the risk of heart disease, even after researchers adjusted for factors such as age, hypertension, smoking, fiber and vitamin E intake. They consumed more than 400 micrograms a day of folate—its RDA is 180 micrograms for non-pregnant women --and more than 3 milligrams of B₆--its RDA is 1.6 milligrams for women. Taking a lot of either vitamin on its own decreased a woman’s risk by about 30 percent. Studies of men have produced similar results. For men, the folate RDA is 200 micrograms and B₆ RDA is 2 milligrams.

Over the course of the study, women completed four detailed questionnaires about their diet. Their main sources of folate were vitamins, cold cereal, orange juice, lettuce, eggs, broccoli, and spinach. The B₆ sources were vitamins, beef, cold cereal, potatoes, bananas, chicken, milk, and tuna fish.

Women who drank alcohol moderately and got lots of the folic acid and vitamin B₆ were the least likely to fall prey to heart disease, the researchers note.

Editorial Comment:
This is an interesting article from the ongoing Nurses' Health Study, which supports the idea of eating one's fruits and vegetables and taking a multivitamin a day. Most multivitamins contain 400 ug of folate, which appears to help lower homocysteine levels. Homocysteine is an amino acid which is associated with an increased risk of atherosclerosis. We have not proved that lowering homocysteine lowers one's risk of CHD. In the meantime, it seems prudent to eat a moderate amount of fruits and vegetables and to consider taking a multivitamin, based on these and other findings.

SOURCES: Rimm, Eric B. ScD, et al, "Folate and Vitamin B₆ From Diet and Supplements in Relation to Risk of Coronary Heart Disease Among Women", The Journal of the American Medical Association, February 4, 1998, Volume 279, Number 5, 359-364; JAMA News, Press Release, February 4, 1998; Mann, Denise, "B Vitamins Found to Prevent Heart Disease", February 3, 1998, Medical Tribune News Service; Reuters Health Information Services, Inc., February 3, 1998.