TUESDAY, Aug. 19 (HealthDay News) -- A study to determine whether folic acid and vitamin B supplements help the heart has been cut short, because the pills weren't doing any good and might have even caused participants harm.

"This confirms what a lot of recent studies have found -- no benefit of taking vitamin B supplements to reduce the risk of heart disease, and it raises a few red flags," said Alice H. Lichtenstein, Gershoff professor of nutrition at Tufts University, Boston.

In the new study, reported in the Aug. 20 issue of the Journal of the American Medical Association, physicians at Haukeland University Hospital in Bergen, Norway, enrolled almost 3,100 volunteers. Three-quarters of them took various doses of vitamin B and folic acid (which is chemically a B vitamin), while the others got a placebo, an inactive substance.

The study was ended early, after an average follow-up of 38 months, because "we could not detect any preventive effect of intervention with folic acid plus vitamin B12 or with vitamin B6 on mortality or major cardiovascular events," the researchers reported.

They did find a slight reduction of stroke, but also a slight increase of cancer in those taking folic acid, but neither of these results reached statistical significance. The study was ended, because another Norwegian study of folic acid and vitamin B supplementation has also hinted at an increased incidence of cancer among users.

But the real bottom line here, according to Lichtenstein, is that "there is no evidence that individuals should take B vitamins to decrease the risk of heart disease, and there may be some evidence that they shouldn't."

The trials were initiated, because observational studies did link high blood levels of a protein called homocysteine with an increased risk of cardiovascular disease. In the new study, homocysteine levels did go down by 30 percent over the course of three years in people taking folic acid and vitamin B. However, there was no related effect on the risk of cardiovascular events.

So, "the observational data was great, but the interventional studies were negative," Lichtenstein said.

Food in the United States is routinely fortified with folic acid, because it reduces the incidence of a specific class of birth defects called neural tube defects. Folic acid is a synthetic form of folate, a B vitamin found in many fruits and vegetables.

"We have been optimistic about the role of antioxidants such as vitamin B in preventing heart disease, yet many of these large trials have shown that there is no benefit," said Dr. Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York City.

It's hard to say whether the reduction in cardiovascular disease seen in some observational trials was caused by vitamin supplementation or because "people taking the supplements have good lifestyles in general," Steinbaum said.

It is also possible that the benefits of vitamin supplements show up only after many years, Steinbaum said. She does recommend a daily multivitamin pill. "But at this point, it is certainly hard to recommend extra supplements when we don't have proof of benefit," Steinbaum said. "What we can recommend is a diet with fruits and vegetables that have antioxidant vitamins in them," she said.

Related MedlinePlus Pages:

• Folic Acid
• Heart Diseases
• Vitamins