Vitamin B supplements do not prevent cancer: study

By Will Dunham

WASHINGTON (Reuters) - Vitamin B supplements do not appear to protect against cancer as some previous research had suggested, according to a U.S. study published on Tuesday.

Women who took a daily supplement that included vitamins B6 and B12 and folic acid, also known as vitamin B9, for about 7-1/2 years were no more or less likely to develop or die from cancer than women who took a placebo, the researchers said.

"This study shows that supplementation with the combined B vitamins provided no beneficial effect and no harmful effect. So in terms of cancer risk, this may not be an effective approach," Dr. Shumin Zhang of Brigham and Women's Hospital and Harvard Medical School in Boston, who led the study, said in a telephone interview.

Researchers have been exploring whether a number of different vitamins may protect against cancer.

The study, published in the Journal of the American Medical Association, involved 5,442 female health-care professionals from around the United States. Their average age was 63.

The women had cardiovascular disease or risk factors for it such as high blood pressure or high cholesterol levels.

Some experts had been hopeful that B vitamins might protect against cancer after earlier studies indicated that people who get more of these vitamins may have a lower risk of developing cancer, especially colon cancer.

But in the new study, the number of women who developed cancer was nearly identical in the vitamin supplement group (187 women) and the placebo group (192 women). The two groups had similar risks for developing any type of cancer or dying from any type of cancer.

The study did find that among women 65 and older, those getting the daily B vitamins were 25 percent less likely to develop any type of cancer and 38 percent less likely to get breast cancer. But Zhang said it is not clear whether this is a genuine finding or simply a chance result.

HEALTH BENEFITS

People can get folic acid and other B vitamins in the diet through leafy green vegetables and fortified cereals or through vitamin supplements.

It is important that people get the proper amount of the various B vitamins, which are essential nutrients for growth, development and numerous other functions. For example, folic acid is important in the production of red blood cells and is important for women to prevent certain birth defects of a baby's brain and spine, known as neural tube defects.

Despite this study's findings, other research suggests that people who eat foods high in folic acid may lower their cancer risk, according to Dr. JoAnn Manson of Brigham and Women's Hospital, who also took part in the study.

Other studies have looked at whether B vitamins may provide additional health benefits. U.S. researchers reported on October 14 in the same journal that high doses of B vitamins failed to slow cognitive decline associated with Alzheimer's disease.

Alzheimer's patients in that study took supplements of vitamins B6 and B12 and folic acid for 18 months.

But a study by researchers at the University of California, Irvine that was published on Tuesday showed that giving high doses of nicotinamide, a form of vitamin B3, prevented memory loss in mice with an animal version of Alzheimer's.

These researchers, whose findings appear in the Journal of Neuroscience, are now doing a study to see if the vitamin also may help people with Alzheimer's disease.

(Editing by Julie Steenhuysen and Eric Beech