Taking folic acid and other B vitamins on regular basis doesn’t prevent breast cancer or cancer in general, according to a seven-year study published in today’s Journal of the American Medical Association.

Researchers at the Brigham and Women’s Hospital of Harvard Medical School evaluated 5,442 female health-care professionals, 42 and older, with a known history of heart disease or 3 or more risk factors associated with the diseases’ onset.

The study’s purpose was to see whether vitamin B6, vitamin B12 and folic acid prevent cancer in women prone to developing heart disease.

At the beginning of the study in 1998, the women were divided into two groups. The first group was given a daily supplement of folic acid, vitamin B6 and vitamin B12, while the second group received a placebo.

For the next 7.3 years, the women were asked about adverse effects, overall health and risk factors. At the end of the study in 2005, out of the 5,442 participants, 379 of them developed invasive cancer. Of them, 187 had received the supplement combination and 192 the placebo. Of the women who developed cancer, 154 developed breast cancer – 70 in the active 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 of breast cancer,” says study author Dr. Shumin Zhang, an associate professor of medicine at Brigham and Women’s Hospital and Harvard Medical School, in Boston.

However, a significantly lower risk of total invasive and breast cancer was detected among women 65 years or older when the trial first started. No reduction in risk was seen in younger women.

“The study findings may have significant impact on public health if substantiated because the rate of cancer incidence is high among elderly persons. The findings are biologically possible because elderly individuals have an increased need for these vitamins,” the study reads.

This is not the first time when researchers want to see whether vitamins play a significant role in cancer prevention. Just last week, the National Cancer Institute halted a trial involving about 35,000 men after finding that vitamin E and selenium didn’t prevent prostate cancer. On contrary, researchers found a higher risk for aggressive prostate cancer in participants taking only vitamin E and a small risk of developing diabetes in subjects taking only selenium.

An earlier study (of a much smaller group) conducted on the effect of selenium supplementation on the recurrence of skin cancers did not demonstrate a reduced rate of recurrence of skin cancers, but did show a reduced occurrence of total cancers.

The American Cancer Society’s Michael Thun said it would be great if taking a pill would decrease cancer risk. “People are hoping for an easy solution, and that's difficult to find,” he added.