A combination supplement of folic acid, vitamin B6 and vitamin B12 did not statistically significantly increase or decrease the risk of colorectal cancer in older women, according to the results of a study published in the Journal of the National Cancer Institute.
Colorectal cancer is the second leading cause of cancer death in the United States. The disease strikes both men and women, with more than 140,000 cases diagnosed each year. Approximately 50,000 people die from colorectal cancer each year.
The chance of an individual developing cancer depends on both inherited genetic factors as well as environmental or behavioral factors. Dietary and lifestyle habits may play a role in the development of cancer and researchers continue to evaluate different foods and supplements and their relationship to different types of cancers. Identifying dietary factors related to cancer could lead to potentially preventive lifestyle habits and strategies.
The relationship between B vitamins and colorectal cancer remains unclear. Some research has indicated that vitamin B6 deficiency could increase the risk of colorectal cancer. Other studies, however, have failed to establish a relationship between B vitamins and colorectal cancer.
The Women’s Antioxidant and Folic Acid Cardiovascular Study was a randomized, double-blind, placebo-controlled clinical trial that included 5,442 female health professionals at high risk for cardiovascular disease. The study ran from April 1998 through July 2005. Participants were randomly assigned to receive a combination pill of folic acid (2.5mg), vitamin B6 (50mg), and vitamin B12 (1mg) or placebo. About a quarter of the patients in this study—1,470 women—were followed for as long as 9.2 years and underwent an endoscopy at some point during that follow-up.
Researchers used data from this group of patients to determine the risk of colorectal cancer and found that the risk was almost identical among participants receiving the vitamin supplements (24.3%) compared to those receiving placebo (24%). Even when data was analyzed by subsite, size, stage, and the number of adenomas, supplementation with folic acid, B6 and B12 had no effect on the risk of colorectal cancer.
The researchers concluded that there was no statistically significant effect of combined supplementation with folic acid, vitamin B6 and vitamin B12 on the risk of colorectal cancer among women at high risk for cardiovascular disease.
 Song Y, Manson JE, Lee IM, et al. Effect of combined folic acid, vitamin B6, and vitamin B12 on colorectal adenoma. Journal of the National Cancer Institute. Published early online October 12, 2012. doi: 10.1093/jnci/djs370
 Larsson SC, Orsini N, Wolk A. Vitamin B6 and risk of colorectal cancer: a meta-analysis of prospective studies. JAMA. 2010;303:1077-1083.