Topic Highlight
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Feb 21, 2013; 19(7): 1005-1010
Published online Feb 21, 2013. doi: 10.3748/wjg.v19.i7.1005
Vitamin B6 and colorectal cancer: Current evidence and future directions
Xue-Hong Zhang, Jing Ma, Stephanie A Smith-Warner, Jung Eun Lee, Edward Giovannucci
Xue-Hong Zhang, Jing Ma, Edward Giovannucci, Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, United States
Stephanie A Smith-Warner, Edward Giovannucci, Department of Nutrition, and Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, United States
Jung Eun Lee, Department of Food and Nutrition, Sookmyung Women’s University, Seoul 140742, South Korea
Author contributions: All authors contributed to conception of the study; ZhangXH drafted the article; Ma J, Smith-Warner SA, Lee JE and Giovannucci E revised it critically for important intellectual content; all authors approved the final version of this article.
Correspondence to: Edward Giovannucci, MD, Professor of Nutrition and Epidemiology, Department of Epidemiology, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, United States.
Telephone: +1-617-4324648 Fax: +1-617-4322435
Received: September 19, 2012
Revised: December 25, 2012
Accepted: January 11, 2013
Published online: February 21, 2013

Colorectal cancer remains the third most common cancer in both women and men worldwide. Identifying modifiable dietary factors is crucial in developing primary prevention strategies. Vitamin B6 is involved in more than 100 coenzyme reactions, and may influence colorectal cancer risk in multiple ways including through its role in one-carbon metabolism related DNA synthesis and methylation and by reducing inflammation, cell proliferation, and oxidative stress. Observational studies of dietary or dietary plus supplementary intake of vitamin B6 and colorectal cancer risk have been inconsistent with most studies reporting nonsignificant positive or inverse associations. However, published studies of plasma pyridoxal 5’-phosphate (the active form of vitamin B6) levels consistently support an approximately 30%-50% reduction in risk of colorectal cancer comparing high with low concentrations. The reasons for the discrepancy in the results between dietary-based and plasma-based studies remain unresolved. Other unresolved questions include the effects of vitamin B6 intake in early life (i.e., childhood or adolescence) and of suboptimal vitamin B6 status on colorectal cancer risk, whether the associations with vitamin B6 differ across molecular subtypes of colorectal cancer, and whether the vitamin B6-colorectal cancer association is modified by genetic variants of one-carbon metabolism.

Keywords: Vitamin B6, Plasma pyridoxal 5’-phosphate, Colorectal cancer, Adenoma, Incidence, Case-control study, Cohort study, Randomized controlled trial, Epidemiology