Folate May Lower Risk of High Blood Pressure In Women

CHICAGO--Young women who consume more than 800 mcg/d of folate may be one-third less likely to develop high blood pressure compared to those who consume less than 200 mcg/d, according to new research presented at the American Heart Association's 58th Annual High Blood Pressure Research Conference.

Folate is a B vitamin native to citrus fruits; tomatoes; leafy green vegetables (e.g., spinach and romaine lettuce); beans (i.e., pinto, navy, and kidney); and grain products. Another source is wheat flour, which undergoes federally mandated fortification with folic acid (the synthetic form of folate). Folate has been shown to reduce levels of homocysteine, a blood component that can damage blood vessels, and may also help blood vessels relax, improving blood flow, according to John P. Forman, M.D., lead author of the as yet unpublished study and a research and clinical fellow at Brigham and Women's Hospital in Boston.

The researchers based their findings on data collected from more than 150,000 women from two large studies--the Nurses' Health Study I (NHS I), which includes 62,260 women, ages 43 to 70, and the Nurses' Health Study II (NHS II), which includes 93,034 women ages 26 to 46--without a history of high blood pressure--to determine if there was a link between level of folate intake--including dietary supplements--and risk of high blood pressure. The study participants were interviewed using a semi-quantitative food frequency questionnaire with questions about dietary and supplemental folate intake at baseline, then administered the same questionnaire every four years. Information about physician-diagnosed high blood pressure was self-reported on health status questionnaires every two years during the eight-year follow-up.

The results showed the most dramatic effects among the younger group (NHS II), although folate benefited older women (NHS I) to a lesser extent. Younger women in the highest folate intake quintile (consuming more than 800 mcg/d) of total folate (from dietary intake plus supplements) had a 29 percent lower risk for high blood pressure than those in the lowest quintile (consuming less than 200 mcg/d of folate). Older women who had total folate intake of 800 mcg/d had a 13 percent lower risk. The results were independent of other factors including exercise, salt intake and diet, which are known to influence the risk of high blood pressure. The researchers also collected data on body mass index; smoking; family history of hypertension; calcium, magnesium and potassium intake; fiber intake; methionine intake; caffeine and alcohol consumption; and use of vitamins B6, B12 and D.

Researchers also looked at the independent effect of supplemental folic acid. Women in NHS II who consumed 800 mcg/d or more of folate mainly as supplemental folic acid had a 48 percent reduction in hypertension risk compared to those whose folate intake was less than 200 mcg/d (and who did not take supplements). Women in NHS I experienced a 40 percent reduction.