B vitamins make no difference in heart disease, cancer

NEW YORK (Reuters Health) - Despite a lot of initial excitement, B vitamins turn out not to lower the risk of a second heart attack in people who've already survived one, according to a large study that experts say closes the issue.

On the other hand, the findings also show that the vitamins -- folic acid and vitamin B12 -- don't appear to increase cancer risk, a concern voiced by some researchers.

"I've been expecting this article for a long time," said Dr. Marta Ebbing of Haukeland University Hospital in Bergen, Norway, who did not work on the study. "It was nice that it finally came along."

While she wasn't surprised by the results, she said they were clearly disappointing.

"During the late 1990s, we really hoped that this safe and cheap treatment would help patients with heart disease," she said.

Early studies had shown that blood levels of the amino acid homocysteine were high in people with heart disease. That led some researchers to speculate that using B vitamins to lower homocysteine levels might in turn protect the heart and decrease the risk of strokes.

While later clinical studies didn't bear out those hopes, it was unclear whether they had the appropriate size and duration to be able to find a potential effect.

The new study, published in the Journal of the American Medical Association and funded by Merck, "is clearly the largest and probably most well-conducted clinical trial on this issue so far," said Ebbing.

The researchers randomly assigned more than 12,000 heart attack survivors to take either placebo pills or vitamin B12 (1 mg daily) and folic acid (2 mg). Then they followed the patients for almost seven years to see if the vitamins would protect them.

About a quarter of the patients on placebo pills suffered a heart attack or a stroke over the follow-up period. In the vitamin group, slightly more people did so, despite their considerably lower homocysteine levels.

"It was worth testing," said a disappointed Dr. Jane Armitage, of the University of Oxford in the U.K., who led the research. "We have done the experiment and unfortunately come out with a negative answer."

Another important question was the safety of folic acid, which is added to foods in many countries -- including the U.S. but not the U.K. -- to avoid the birth defects that may result if pregnant women don't get enough of the vitamin.

Cancer, which was the main concern, was not statistically increased in patients who took the vitamins.

The results "are reassuring in the sense that there were no safety concerns," said Armitage.

However, earlier studies have pointed to potential cancer risks, and Ebbing, who has studied the issue herself, said the long-term consequences of vitamin B supplements were still uncertain.

What is certain, she added, is that taking these vitamins doesn't help the heart, despite what labels on commercial products might say.

"My advice to heart patients would be that if you have high homocysteine levels you have a good reason to live as healthily as possible," she said.

Apart from standard drugs such as aspirin and blood pressure- and cholesterol-lowering medications, she recommended that heart patients start jogging and eating more healthy foods.

"The way to treat this is not to take vitamins but to live more healthily," she said.

SOURCE: link.reuters.com/jej53m JAMA, online June 22, 2010.