SHANGHAI, CHINA. A team of American and Chinese researchers has discovered that folic acid (folate) is highly effective in preventing breast cancer in both pre- and postmenopausal women. Their investigation involved 1321 women with breast cancer and 1382 healthy controls. The women were between the ages of 25 and 64 years when they enrolled in the Shanghai Breast Cancer Study during 1996-98.
The researchers found a clear correlation between dietary intake of folic acid and the risk of breast cancer. Women with a daily intake of 345 micrograms or higher had a 38 per cent lower risk than did women with an intake of less than 195 micrograms – after adjustment for total vegetable, fruit and animal food intake. The protective effect of folic acid was even more pronounced in women who also had a high dietary intake of vitamin B6, vitamin B12 and methionine. Women with a daily intake equal to or higher than 345 micrograms of folic acid, 8.47 micrograms of vitamin B12, 2 mg of vitamin B6, and 1.9 grams of methionine had a 53 per cent lower risk of breast cancer than did women with daily intakes at or below 195 micrograms of folic acid, 1.32 micrograms of vitamin B12, 1.35 mg of vitamin B6, and 1.27 grams of methionine.
Researchers believe that folic acid exerts its protective effect by preventing errors in DNA replication and by helping to regenerate methionine, a vital component in DNA synthesis. They also point out that both vitamin-B12 and vitamin-B6 are vital cofactors required for folic acid to "do its job". NOTE: Most multivitamins have levels of folic acid, vitamin B6 and vitamin B12 well above the levels found to be beneficial in the Shanghai study.
Shrubsole, Martha J., et al. Dietary folate intake and breast cancer risk: results from the Shanghai Breast Cancer Study. Cancer Research, Vol. 61, October 1, 2001, pp. 7136-41