Vitamin B Not Effective in Preventing Cancer

B vitamins are essential nutrients for growth, development and numerous bodily functions. They play a major role in the breakdown of carbohydrates into glucose, providing energy for the body, as well as the breakdown of fats and proteins, which aids the normal functioning of the nervous system. However, while B vitamins are needed to help avoid many health conditions, cancer doesn’t appear to be one of them, as some previous research had suggested.

So says a new U.S. study, which involved 5,442 female health-care professionals from around the country. All of the women were over 42 years of age, and either had cardiovascular disease or risk factors for it, such as high blood pressure or high cholesterol. Over the course of 7.3 years, from April 1998 through July 2005, the women took either a supplement containing 2.4 milligrams of folic acid, 50 milligrams of vitamin B6 and 1 milligram of vitamin B12, or a placebo.

During that time, 187 in the treatment group and 192 in the placebo group developed invasive cancer. Of the women who developed cancer, 154 developed breast cancer—70 in the treatment group and 84 in the placebo group. “In women at risk of cardiovascular disease, we found that folic acid, vitamin B6 and vitamin B12 had no beneficial or harmful effects on the risk of invasive cancer or breast cancer,” said study author Dr. Shumin Zhang, an associate professor of medicine at Brigham and Women’s Hospital and Harvard Medical School in Boston.

However, the study did find that there appeared to be a protective effect from the supplement treatment in women 65 and older. Those taking the daily vitamins were 25 percent less likely to develop any type of cancer and 38 percent less likely to get breast cancer. “If the finding is real and substantiated, the results may have public health significance because the incidence rates of cancer are high in elderly persons. The finding is biologically plausible because elderly individuals have increased requirements for these B vitamins,” the study authors wrote.

It is important that people get the proper amount of the various B vitamins. Vitamin B6, or pyridoxine, can be found in foods such as liver, meat, brown rice, fish, butter and soybeans. Vitamin B12 can be found in liver, meat, egg yolk, poultry and milk. Folic acid is found in green vegetables, liver, yeast and whole grain cereals. Since January 1998, folic acid has been added to many food items in the United States, such as cereals and breads, primarily to reduce the risk of neural tube birth defects. “There are really good reasons for women to take folic acid, especially if they're planning on having a baby, because there’s really conclusive evidence that it can reduce birth defects. But, for the average woman in terms of cancer risk, folic acid and B vitamins don’t seem to increase or reduce risk,” Dr. Zhang said.

The study was published in the November 5 issue of the Journal of the American Medical Association.