The supplements do have their uses, Manson was quick to add. Folic acid is known to prevent birth defects that affect a baby's brain and spine. "We strongly recommend that women who might become pregnant take additional folic acid supplements," she said.
Manson used the word "additional," because bread and other grain products in the United States and other developed countries are fortified with folic acid. Natural sources of folic acid include green leafy green vegetables and citrus fruits.
Supplements could be recommended routinely for people in countries where no such fortification is done, said Dr. Eva Lonn, professor of medicine at McMaster University in Hamilton, Ontario, Canada, who wrote an accompanying editorial in the journal.
"But what we have learned from the trials in North America, where folic acid is added to flour products, is that there is no role for homocysteine screening or treatment in cardiovascular disease," Lonn said.
Some studies have indicated that folic acid supplements might protect against Alzheimer's disease, she said. "But they aren't conclusive," she added. "We need randomized trials with hard endpoints."
A woman's guide to folic acid is offered by the U.S. National Women's Health Information Center.
SOURCES: JoAnn E. Manson, M.D., chief of preventive medicine, Brigham and Women's Hospital, Boston; Eva Lonn, M.D., professor of medicine, McMaster University, Hamilton, Ontario, Canada; May 7, 2008, Journal of the American Medical Association
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