A higher intake of folate and possibly vitamin B6 may reduce the risk of developing breast cancer, report researchers in the US.
The team from Brigham and Women's Hospital and Harvard Medical School, Boston, also report that adequate levels of folate may be particularly important for women at higher risk of developing breast cancer because of higher alcohol consumption.
Folate, found in foods such as orange juice, leafy greens and fortified breakfast cereals, has already been shown to reduce the elevated risk of breast cancer associated with moderate alcohol consumption. However, data relating plasma folate levels to breast cancer risk are sparse, wrote the team in this month's Journal of the National Cancer Institute.
The researchers investigated the association between plasma folate and other vitamins with breast cancer in a prospective, case-control study. They studied the blood samples of 712 breast cancer case patients matched with 712 control subjects. Dietary information was obtained from food frequency questionnaires.
They report that the inverse association between plasma folate and breast cancer risk was highly statistically significant among women consuming at least 15 g of alcohol daily, about one drink, in contrast with that of women consuming less than this amount. Women with the highest blood folate levels who also drank regularly were 89 per cent less likely to go on to develop breast cancer than those who had the lowest levels of the B vitamin.
Also plasma vitamin B12 levels were inversely associated with breast cancer risk among premenopausal women but not among postmenopausal women. Plasma homocysteine was not associated with breast cancer risk.