Higher intake of folic acid is associated with a decreased risk of developing high blood pressure, particularly among younger women, according to Harvard researchers.

Small studies have suggested that high-dose folic acid supplementation may lower blood pressure, Dr. John P. Forman and colleagues note in this week’s Journal of the American Medical Association, but there have been no large, forward-looking studies examining this issue.

The team analyzed information on nearly 94,000 women ages 27 to 44 years participating in the Nurses’ Health Study II, none of whom had high blood pressure when the study began. Their folate intake was estimated based on food questionnaires and information regarding folate-containing supplements.

During 8 years of follow-up, 7373 of the women developed hypertension.

After adjusting for factors such as physical activity, weight and family history, women who consumed at least 1000 micrograms per day of total folate had a 46 percent lower risk of becoming hypertensive compared with those with an intake less than 200 micrograms per day.

Forman’s team also examined data on more than 62,000 older women (43 to 70 years of age) in the Nurses’ Health Study I, among whom 12,347 developed high blood pressure.

In this group, the risk of hypertension was reduced 18 percent for the highest versus lowest folate intake.

The benefit came primarily from folate supplementation rather than dietary folate, the researchers found.

This may be because relatively few subjects consumed very high quantities of dietary folate, or perhaps folate from supplements is more readily used by the body.

SOURCE: Journal of the American Medical Association, January 18, 2005.