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B vitamins make no difference in heart disease, cancer

Last Updated: 2010-06-22 19:27:15 -0400 (Reuters Health)

June 23, 2010

By Frederik Joelving

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.

The new study, published in the June 23/30 issue of 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 Dr. Marta Ebbing of Haukeland University Hospital in Bergen, Norway, who did not work on the study.

"I've been expecting this article for a long time," she said. "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.

For the study reported this week in JAMA, Dr. Jane Armitage, of the University of Oxford in the U.K. and colleagues randomly assigned more than 12,000 myocardial infarction patients 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.

About a quarter of the patients in the placebo group suffered another 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. Armitage. "We have done the experiment and unfortunately come out with a negative answer."

Another important question was the safety of folic acid. 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 Dr. Armitage.

However, earlier studies have pointed to potential cancer risks, and Dr. 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.

http://jama.ama-assn.org/cgi/content/short/303/24/2486

JAMA 2010;303:2486-2494.

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B vitamins make no difference in heart disease, cancer

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