Source: American Journal of Clinical Nutrition, 2009;89(2):624-33.
Research: Folic acid (also known as folate) is a member of the water-soluble B vitamin group. It is also one of the most common vitamin deficiencies. Research has suggested that very high folate intake may be protective against breast cancer. This trial included 35,023 women aged 50-76 years who participated in the Vitamins and Lifestyle (VITAL) cohort study.
Results: Between 2000 and 2006 a total of 743 women were diagnosed with invasive breast cancer. Researchers found that women who consumed 1272 or more dietary folate equivalents (DFE)/day of total folate over an average 10-year period had a 22% decrease in breast cancer risk compared with women consuming 345 DFE/day or less. It was also discovered that the effect of very high folate intake was more pronounced when focusing on estrogen receptor (ER)-negative tumors alone, which is particularly important since ER-negative breast cancers generally have a poorer prognosis than their ER-positive counterparts. This research appears to indicate that high intakes of folate may actually be protective against breast cancer, especially ER-negative tumors.