Folic acid, the little-known B vitamin recommended to pregnant women to reduce spinal birth defects, could prevent up to 50,000 heart disease deaths a year, researchers say.

"We think there's good enough evidence that the whole population would benefit from increasing folic acid intake," says Shirley Beresford, associate professor of epidemiology at the University of Washington School of Public Health, Seattle.

Her team analyzed findings of 38 studies and found "very strong evidence" that folic acid can reduce heart disease risk caused by increased levels of homocysteine, an amino acid byproduct believed to impede blood flow in the arteries.

The researchers recommend putting folic acid in the USA's flour and cereals, which they estimate could prevent about 49,000 deaths a year.

Other possible, though less effective measures:

Eating two or three more servings a day of fruits and vegetables (orange juice, dried beans and spinach), which could prevent 26,000 deaths.

Taking a supplement of 400 micrograms of folic acid daily (the recommended daily allowance until it was cut in half in 1989), which could prevent 27,000 deaths.

Some say supplementation would be premature without more information, including details on optimal doses: "We await more definitive evidence that supplementation would have the desired benefit," says Ronald Krauss of the American Heart Association.

The report, in Tuesday's Journal of the American Medical Association, calls for clinical trials, but "in the meantime, policies for increasing folic acid intake could have a considerable effect."

By Leslie Miller, USA TODAY