Kim SJ, et al. - In this case–control study, researchers assessed the links between folic acid, vitamin B6, and vitamin B12 supplement use and breast cancer risk among BRCA mutation carriers via unconditional logistic regression. Study participants included 129 Canadian patients with breast cancer and 271 Canadian control participants. Categories of supplement use were never or ever use. Total average daily supplement use was categorized as never, moderate, and high based on tertiles. The investigators noted a remarkably reduced risk of breast cancer in association with the use of any folic acid-containing supplement vs never use of a folic acid-containing supplement. This was found to be significant for BRCA1 mutation carriers only. They also noted a decreased risk of breast cancer in association with moderate vitamin B12 supplement intake vs never use. Overall, a possible protective impact of moderate folic acid- and vitamin B12-containing supplement use was suggested for BRCA-associated breast cancer, particularly among BRCA1 mutation carriers.