Low Levels of Vitamin B6 May Increase Risk of Colorectal Cancer
Individuals with low blood levels of an active form of vitamin B6 or low dietary intake of vitamin B6 may have an increased risk of developing colorectal cancer. These results, based on an analysis of several previously published studies, were published in the Journal of the American Medical Association.
Vitamin B6 is a water-soluble vitamin that performs a wide variety of functions in the body. Foods that contain vitamin B6 include fortified cereals, beans, meat, poultry, fish, and some fruits and vegetables. Pyridoxal 5’-phosphate (PLP) is the principal active form of vitamin B6 and can be measured in blood.
Although few people in the United States have clinical signs of vitamin B deficiency, many older Americans have low blood levels of vitamin B6.
Some previous studies have suggested that higher levels of vitamin B6 may reduce the risk of colorectal cancer. To further explore the relationship between vitamin B6 and risk of colorectal cancer, researchers conducted a combined analysis of nine previous studies of vitamin B6 intake and four previous studies of blood PLP levels.
- Overall, individuals with the highest intake of vitamin B6 were 10% less likely to develop colorectal cancer than individuals with the lowest intake of vitamin B6. This result was not statistically significant, however, suggesting that it could have occurred by chance alone. One study appeared to have an inordinate effect on these results, and when this study was excluded a statistically significant 20% reduction in risk was observed among individuals with the highest vitamin B6 intake.
- Higher blood PLP levels were also linked with a reduction in risk of colorectal cancer. Each 100-pmol/mL increase in blood PLP reduced the risk of colorectal cancer by 49%.
The results of this analysis suggest that higher blood PLP and higher dietary intake of vitamin B6 may reduce the risk of colorectal cancer.
Reference: Larsson SC, Orsini N, Wolk A. Vitamin B6 and risk of colorectal cancer: a meta-analysis of prospective studies. JAMA. 2010;303:1077-1083.
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