Written by Chrystal Moulton, Staff Writer. Dietary folate, equal to or less than 343mcg per day, along with dietary and supplemental intakes of vitamin B6 and riboflavin, were associated with a reduced risk of colorectal cancer.
Colorectal cancer is characterized by noncancerous clusters of cells in the lining of the colon and rectum, which over time may develop into abnormal and often cancerous tissue growth or polyps. There is no specific cause of colorectal cancer and individuals generally do not experience any symptoms during the early stages of the disease.(1) In the US, documented trends indicate a decrease in both men and women in the occurrence of colorectal cancer by about 3.2% and 2.8% respectively. (2)
In the Women’s Health Initiative Observational study, researchers investigated the relationship between vitamin B6, vitamin B12, folate, riboflavin and colorectal cancer during the period before, during and after the implementation of folic acid fortification of foods in the US. A total of 88,045 postmenopausal women aged 50 to 79 years were recruited from 1993-98. Participants completed a food frequency questionnaire at the beginning of the trial and a medical history update questionnaire annually. Approximately 1,003 cases of colorectal cancer were found among participants during study.
Researchers compared dietary (from food) and supplementary intakes of folate, B6, B12, and riboflavin to the incidence of colorectal cancer. Participants were categorized into 4 groups (quartiles) based on B-vitamin consumption. Quartile 1 signified the group with the lowest intake of B-vitamins, while quartile 4 signified the group with the largest intake of B-vitamins. Hazard ratios were calculated for each quartile.
Researchers found that the highest intakes of dietary folate (≥343mcg per day, HR=.79, p=0.03) and total intakes of vitamin B6 and riboflavin, which include both dietary and supplemental intakes, were associated with a reduced risk of colorectal cancer (B-6: > 3.88mg per day, HR=.73, p < 0.01), (riboflavin: > 3.97mg per day, HR=.75, p< 0.01).
Researchers were also curious to know if the FDA-mandated folic acid fortification program from 1994 to 1998 may be associated with some risk of developing colorectal cancer. They found that for dietary folate above or equal to 343mcg per day, an increased risk of colorectal cancer was observed specifically in individuals exposed to fortification for 3 to < 6 years (HR=1.54, p < 0.01) and 6-9yrs (HR=3.24, p < 0.01). An explanation for why folic acid showed reduced risk of colorectal cancer for increases in folic acid intake up to 343 mcg per day and increased risk for intakes over 343 mcg per day should be provided by additional studies.
Source: Zschäbitz, Stefanie, et al. “B vitamin intakes and incidence of colorectal cancer: results from the Women’s Health Initiative Observational Study cohort.” The American journal of clinical nutrition (2013): ajcn-034736.
© 2012 by the American Society for Nutrition
Posted February 20, 2013.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
- Colon Cancer. PubMed Website. Accessed January 23, 2013.
- Colorectal Cancer Trends on Center for Disease Control and Prevention (CDC website). Accessed January 23, 2013.
- B vitamin intakes and incidence of colorectal cancer: results from the Women’s Health Initiative Observational Study cohort. Zschäbitz S, Cheng TY, Neuhouser ML,et al. Am J Clin Nutr. 2013 Feb;97(2):332-43.doi: 10.3945/ajcn.112.034736. Epub 2012 Dec 19.
