By David Liu, PHD

Sunday Dec 23, 2012 (foodconsumer.org) -- Eating foods high in vitamin B-6 and riboflavin or taking their supplements may reduce the risk of colorectal cancer while eating food fortified with folate may increase the risk, according to a study published in American Journal of Clinical Nutrition.

The study led by S. Zschäbitz S from Cancer Prevention Program, Fred Hutchinson Cancer Research Center in Seattle, WA and colleagues found postmenopausal women in the highest quintile of dietary and total intakes of vitamin B6 were 20 and 20%, respectively less likely to be diagnosed with colorectal cancer, compared with those in the lowest quintile of intakes.

The study also found women in the highest total intakes of riboflavin were 19 percent less likely to develop colorectal cancer or regionally spread disease, compared with those in the lowest quintile.

The study was based on data from 88,045 postmenopausal women enrolled in the Women's Health Initiative Observational Study and intended to examine the association between intake of b vitamins including folate, riboflavin, vitamin B-6, and vitamin B-12 and risk  of colorectal cancer.

Among current light drinkers who consumed less than 1 drink or 13 grams of alcohol per week, B vitamin intakes were found inversely correlated with colorectal cancer risk.

And women who had experienced the initiation of folate fortification for 3 to less than 9 years were found to have increased risk of colorectal cancer.

Folate is added to wheat flour to reduce birth defects, but for women who are at a child-bearing age, folate fortification can increase their risk for breast cancer.   It may be wise for those women to use foods without folate fortified. Folate is high in green leafy vegetables which can be eaten in large quantity without safety issues.

The researchers concluded "Vitamin B-6 and riboflavin intakes from diet and supplements were associated with a decreased risk of CRC (colorectal cancer) in postmenopausal women. Associations of B vitamin intake were particularly strong for regional disease and among women drinkers who consumed alcohol infrequently."

Additionally, they concluded "Our study provides new evidence that the increased folate intake during the early postfortification period may have been associated with a transient increase in CRC risk."