Supplements don't lower heart, stroke risk in women

Women who took folic acid and B vitamin supplements had the same rate of cardiovascular disease as women who didn't, a new study in the Journal of the American Medical Association reports, adding to the list of substances that showed promise in earlier observational studies but not in more rigorous trials.

Researchers led by Dr. JoAnn E. Manson of Harvard Medical School and Brigham and Women's Hospital studied 5,442 women in the health profession who were at least 42 years old and had a history of cardiovascular disease or three or more risk factors for it. For more than seven years, half were given a pill containing folic acid plus two B vitamins and half were given a matching placebo.

The supplements did lower the women's levels of homocysteine, an amino acid previously implicated in the risk of cardiovascular disease. But women randomly assigned to receive the vitamins had about the same number of heart attacks, strokes, coronary artery blockages, or deaths as the women who got dummy pills.

"This randomized trial casts further doubt on the role of folic acid and B vitamins in preventing cardiovascular disease, despite their effect in lowering homocysteine," Manson said in an interview. "It may take substantial lowering or it may be beneficial in people with extremely high levels of homocysteine, but this finding suggests folic acid and B vitamins should not be taken with the express intent of lowering cardiovascular disease."

This was the largest, longest trial of the supplements in women and the first to include women who had not yet developed heart disease or stroke, Manson said. Similar results had already been found in men.

Folic acid is still important for women of childbearing age because of its proven value in preventing birth defects such as neural tube disorders, Manson emphasized. It also doesn't meant that the vitamins don't have other health benefits, but like vitamins E and C before them, most alleged benefits have not been confirmed by research.

"Once again experimental and observational data do not always translate into therapeutic benefits," Dr. Eva Lonn of McMaster University in Hamilton, Ontario, writes in an accompanying editorial.

Antioxidants, vitamins, postmenopausal hormone therapy, and drugs to raise "good" cholesterol also looked promising in earlier trials. But later trials that accounted for the influence of diet, lifestyle and other factors could not find the same benefit and even discovered harm from the treatments.

"It does highlight the fact that markers for disease may identify individuals at high risk. It does not automatically mean lowering biomarkers lowers risk," Manson said. "Lowering biomarkers has to be tested."

Biomarkers that have passed the test and found to be true harbingers of disease are high "bad" cholesterol and high blood pressure, she said.