Building on preliminary data, researchers at Harvard-affiliated Brigham and Women’s Hospital (BWH) have documented that high folate (vitamin B-9) and vitamin B-6 levels may improve a woman’s chances of preventing breast cancer. Additionally, researchers observed that adequate folate levels may be particularly important for women who are at higher risk of breast cancer due to higher alcohol consumption. The new findings are the latest results from the landmark BWH-based Nurses’ Health Study, and appear in the March 5 issue of The Journal of the National Cancer Institute.
“The benefits of folic acid in reducing birth defects and cardiovascular disease have been well established; however, its protective impact on breast cancer has been less clear,” said Shumin Zhang of BWH and the School of Public Health. “The findings from this large study suggest more precisely that by ensuring adequate levels of folate and vitamin B-6 – by consuming foods rich in these nutrients and taking vitamin supplements – a woman’s risk of breast cancer may be reduced.”
The researchers found that women with the highest recorded folate levels in their blood appeared to be 27 percent less likely to develop breast cancer, compared to women with the lowest folate levels. This association between folate and breast cancer risk was strongest among women who consumed moderate amounts of alcohol – a group already at greater risk for the disease. When plasma folate and alcohol intake were examined in combination, higher alcohol intake only appeared to increase risk of breast cancer in women with low folate levels. The research team observed that for women consuming less than one glass of alcohol a day, high levels of folate eliminated their increased risk of breast cancer by 28 percent. An inverse association between vitamin B-6 levels and breast cancer was also observed; however, it appeared most significant in postmenopausal women.
Folate and vitamin B-6 are found naturally in foods such as oranges and leafy green vegetables. Breakfast cereals and wheat flour have been fortified with folic acid (the synthetic form of folate) since 1998, following a mandate by the Food and Drug Administration to increase vitamin B levels in the average diet. Though still not fully understood, scientists hypothesize that folate’s role in DNA construction may explain why it helps stave off disease and is instrumental in reducing some birth defects by up to 70 percent.
“The prospect that folate and vitamin B-6 may have the potential to be protective against breast cancer is encouraging as we look toward more ways to proactively fight disease onset,” said Zhang, also of Harvard Medical School. “Women may want to monitor their intake of these nutrients more closely, especially those who consume moderate amounts of alcohol, where it appears high folate levels play a role in offsetting their increased risk of breast cancer.”
These findings were based on analysis of 712 breast cancer patients and 712 control subjects selected from a pool of 32,826 women enrolled in the Nurses’ Health Study who provided blood samples at the onset of the study. The subjects were followed for six years, during which individual health and diet information was collected.