Men with low vitamin B6 intake have a greater risk of colorectal cancer

The July, 2007 issue of the Journal of Nutrition published a report by researchers in Japan that found an association between reduced vitamin B6 intake and an increased incidence of colorectal cancer.

Shoichiro Tsugane of Japan's National Cancer Center and his associates utilized data from the Japan Public Health Center-based Prospective Study Group, an ongoing cohort study of cancer, cardiovascular disease and other lifestyle diseases among the residents of 11 areas in Japan. The current study included 38,107 men and 43,077 women who responded to five-year follow-up surveys between 1995 and 1999. Food frequency questionnaires included in the surveys were used to estimate folate, vitamin B6, vitamin B12, and methionine intake. The authors hypothesize that low intake of these nutrients could cause colon cancer by inducing aberrations in DNA methylation and synthesis.

Participants were followed through 2002, during which 335 men and 191 women developed cancer. Men whose intake of vitamin B6 was in the top 25 percent of subjects had an approximately 35 percent lower risk of colorectal cancer than men in the lowest quarter. Among men in the lowest 25 percent of B6 intake, drinking more than 150 grams alcohol per week doubled the risk of colorectal cancer compared to men who drank less, however, a greater intake of vitamin B6 reduced this risk. None of the vitamins examined were associated with a protective effect among women.

The authors state that a protective effect for vitamin B6 among those who drink alcohol is biologically plausible because alcohol interferes with B6 absorption, reduces the synthesis of methionine from homocysteine, and lowers glutathione levels. They conclude that a higher intake of the vitamin may be of benefit to those who consume more than 150 grams alcohol per week.