Folic acid lowers blood concentrations of homocysteine

A new study published in the October 2005 issue of the American Journal of Clinical Nutrition indicates that a dosage of at least 800 mcg of folic acid is needed to maximally reduce plasma homocysteine concentrations. Increased blood homocysteine levels are considered to be a risk factor for cardiovascular disease.

This meta-analysis of 25 studies evaluated the effect of various doses of folic acid on plasma homocysteine. Doses of 800 micrograms provided a significantly greater reduction in plasma homocysteine compared to 400 micrograms. Supplementation with 800 micrograms folic acid per day was associated with a 23 percent reduction in homocysteine, compared to a 20 percent reduction associated with 400 micrograms. A dosage of 200 mcg was associated with a 13 percent reduction. Higher doses provided only a slightly greater benefit. The addition of vitamin B12 was associated with a synergistic benefit.

Although some fortified foods contribute to daily intake in the U.S., many multi-nutrient supplements provide just 400 mcg of folic acid.

American Journal of Clinical Nutrition, Vol. 82, No. 4, 806-812, October 2005