B vitamins help prevent colorectal cancer
Tuesday Nov 5, 2013 (foodconsumer.org) -- A new study in the American Journal of Clinical Nutrition suggests that early folate fortification may have increased the risk of colorectal cancer while B vitamin intakes may help lower the risk among postmenopausal women.
Cornelia M Ulrich from National Center for Tumor Diseases and German Cancer Research Center in Heidelberg, Germany and colleagues conducted the study and found intake of dietary and total vitamin B 6 was inversely associated with the risk of colorectal cancer among postmenopausal women.
Hower, the study also found dietary folate intake associated with elevated risk of the disease among women who experienced 3 to 9 years of initial folate fortification.
The study based on data from the Women's Health Initiative Observational Study cohort was intended to examine how one carbon metabolism nutrients affect colorectal carcinogenesis and how the risk is affected by mandated folic acid fortification and alcohol consumption in 88,045 postmenopausal women enrolled in the study during 1993 to 1998. Considered factors included folate, roboflavin, vitamin B-6 and vitamin B12.
Postmenopausal women in the highest quartile of dietary and total intakes of vitamin B-6 were found 20 % less likely to be diagnosed with colorectal cancer, compared with those in the lowest quartile.
Total intake of riboflavin in the highest quartile were correlated with 19% reduced overall risk of colorectal cancer and regionally spread disease, compared with the lowest quartile.
Among current alcohol drinkers who drunk less than one drink or 13 grams of alcohol per week, B vitamin intakes were inversely correlated with colorectal cancer risk.
However, among women who had experienced the initial folate fortification for three to 9 years, dietary folate intake was positively associated with colorectal cancer risk. This means that too high folate intake from fortified foods may increase the risk of colorectal cancer among postmenopausal women.
The study concluded "Vitamin B-6 and riboflavin intakes from diet and supplements were associated with a decreased risk of CRC (colorectal cancer) in postmenopausal women" and "Associations of B vitamin intake were particularly strong for regional disease and among women drinkers who consumed alcohol infrequently.
The study also concluded "the increased folate intake during the early postfortification period may have been associated with a transient increase in CRC (colorectal cancer) risk."
B vitamins are mostly found in green leafy vegetables. The study could mean that eating large amounts of green leafy vegetables may help lower the risk of colorectal cancer. At least, prior studies have linked high intake of dietary fiber to reduced risk of this cancer.
Other studies also found that high intake of fortified folate or folic acid was associated with increased risk of cancer.
B vitamins like B vitamin complex are available as a dietary supplement. (David Liu)
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