Getting enough vitamin B6 each day from supplements or foods such as fortified cereals can cut a man’s risk of developing colorectal cancer, according to a study in the April issue of Cancer Epidemiology Biomarkers & Prevention.
Vitamin B6 is a crucial ingredient in DNA production. Low levels of this vitamin have been linked to the DNA changes that can lead to colorectal cancer, as well as other types of cancer. Vitamin B6 deficiency is also associated with inflammatory markers that are related to cancer development.
Previous research has indicated that vitamin B6 may lower colorectal cancer risk, but it hasn’t been clear whether this risk reduction is influenced by other B vitamins, inflammatory processes, or other factors, according to Jung Lee, ScD, Research Fellow at Channing Laboratory and the Department of Medicine at Brigham and Women’s Hospital and Harvard Medical School.
To add to the existing evidence on vitamin B6 and colorectal cancer risk, and to determine whether that potential risk reduction is mediated by other B vitamins and inflammation, Dr. Lee’s team of researchers looked at data from the Physicians’ Health Study, a prospective study of more than 22,000 male doctors. Of participants who provided blood for the study, 197 men with colorectal cancer patients and 371 matched cancer-free controls were evaluated in the current study.
The researchers measured levels of pyridoxal 5’-phosphate (PLP), the active form of vitamin B6, in the participants’ blood. They also measured blood levels of folate (a B vitamin) and vitamin B12, as well as markers of inflammation, and they controlled for known colorectal cancer risk factors such as body mass index (BMI), exercise, and consumption of red meat and alcohol.
Men with high PLP levels had a 53 percent lower risk of colorectal cancer than those with low PLP levels. The effect of plasma PLP on colorectal cancer was independent of other B vitamins related to DNA modification or production, or inflammation, which indicates that vitamin B may reduce colorectal cancer risk by another mechanism, for example by blocking the spread of cancer cells, reducing the oxidative stress that can cause cells to turn cancerous, or inhibiting the formation of blood vessels that feed cancerous tumors (angiogenesis), according to Dr. Lee.
This and earlier studies seem to agree that vitamin B6 can help prevent colorectal cancer, yet according to the U.S. National Health and Nutrition Examination (NHANES) study, a large number of Americans have low blood levels of vitamin B6, even if they are getting the recommended amount every day in their diet (1.3 mg for adults under age 50, and up to 1.7 mg for those aged 51 and over).
“It is clear that PLP levels are modified by vitamin B6 intake,” Dr. Lee says. “Thus, consuming more food sources of vitamin B6 can be recommended.” Getting extra vitamin B6 may be especially important for smokers, the elderly, and current and former oral contraceptive users, because the NHANES study found these groups to have lower-than-normal levels of the vitamin.
If you are interested in taking vitamin supplements above the recommended daily allowances speak to your licensed healthcare practitioner.
Lee JE, Li H, Giovannucci E, Lee I, Selhub J, Stampfer M, Ma J. Prospective study of plasma vitamin B6 and risk of colorectal cancer in men. Cancer Epidemiol Biomarkers Prev. 2009;18(4).