Washington, Nov 5 : Daily doses of multivitamin supplements, including folic acid and vitamin B6 and B12, have no effect in preventing cancer in women, according to a group of researchers.
Folate, vitamin B6, and vitamin B12 (water-soluble, essential B vitamins) are thought to play an important role in cancer prevention.
The study found that folic acid and vitamin B6 and B12 had no significant effect on the overall risk of cancer, including breast cancer, among women at high risk of cardiovascular disease.
The research team led by Dr Shumin M. Zhang, Sc.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, conducted a trial o evaluate the effect of combined folic acid, vitamin B6, and vitamin B12 treatment on cancer risk in women at high risk for cardiovascular disease.
The study involved 5,442 U.S. female health professionals age 42 years or older, with pre-existing cardiovascular disease or three or more coronary risk factors.
They were were randomly assigned to receive either a daily combination of folic acid (2.5 mg.), vitamin B6 (50 mg.), and vitamin B12 (1 mg.) or a matching placebo. They were treated for 7.3 years, from April 1998 through July 2005.
The authors found, "a total of 379 women developed invasive cancer (187 in the active treatment group and 192 in the placebo group."
"Compared with placebo, women receiving the active treatment had similar risk of developing total invasive cancer, breast cancer, or any cancer death," the authors said.
A significantly reduced risk was observed for total invasive cancer and breast cancer among women age 65 years or older at study entry, but no reductions in risk were observed among younger women 40-54 years or 55-64 years.
"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," they said.
"The finding is biologically plausible because elderly individuals have increased requirements for these B vitamins.
"In conclusion, treatment with combined folic acid, vitamin B6, and vitamin B12 provided neither beneficial nor harmful effects on overall risk of total cancer, breast cancer, or deaths from cancer among women at high risk for CVD," they added.
The study appears in the issue of JAMA.