Folate supplement may raise breast cancer risk

Researchers in the UK report a possible increase in the risk of developing breast cancer among women who take folate supplements while pregnant.

However, as senior investigator Dr. Andy R. Ness of the University of Bristol, stressed in a statement, "it is important that we don't confuse women about the need to take folic acid supplements early in pregnancy."

Folic acid is the synthetic form of folate, a B vitamin found in green leafy vegetables, fruits and dried beans. Research has shown that taking the supplements before conceiving and early in pregnancy reduces the risk of birth defects such as spina bifida that affect the brain and spinal cord.

The current concerns come from a study, published in the British Medical Journal, involving nearly 3,000 pregnant women who randomly assigned to take a high or low dose of folate, or an inactive placebo, between 1966 and 1967.

Records from the study were linked with those of a National Health Service Central Registry of causes of any deaths. By 2002, a total of 210 women had died, with 40 deaths attributed to cardiovascular disease, 112 to cancer, and 31 specifically to breast cancer.

There were 17 deaths from breast cancer in the placebo group (0.9 percent), six among those assigned to low-dose folate (1.3 percent), and eight among those given high-dose folate (1.6 percent).

However, even after factoring demographics, smoking, weight and blood pressure, none of the differences between groups were significant from a statistical standpoint.

"It is entirely possible that this is a chance finding - so further scientific studies are required to examine the association, if there is one, before we reach any conclusions," said Ness.

In an interview with Reuters Health, Dr. Godfrey P. Oakley, co-author of an accompanying editorial, agreed. "This is an extremely preliminary report" and "it is very likely that this is a statistical fluke," he said.

Oakley and Dr. Jack S. Mandel, epidemiologists at the Rollins School of Public Health of Emory University in Atlanta, point out that numerous other studies have tied folate consumption to reduced rates of breast cancer, heart attack and stroke.

SOURCE: British Medical Journal, December 11, 2004.