Vitamin B6 may reduce Colorectal Cancer risk.

Article by Arnie Gitomer

Increased intake of vitamin B6 from dietary and supplements may reduce the risk of colorectal cancer by over 20 per cent, suggests a large Scottish study.

Almost 5,000 people took part in the study, which reported a dose-dependent link between intake of the vitamin and the risk of colorectal cancer, report the researchers in the journal Cancer Epidemiology Biomarkers & Prevention.

The study, by researchers from the University of Edinburgh, Western General Hospital (Edinburgh) and the University of Aberdeen, adds to an ever growing body of science supporting the potential colorectal benefits of higher intake of the B vitamins.

There are 363,000 new cases of colorectal cancer every year in Europe, with an estimated 945,000 globally. There are about 492,000 deaths from the cancer each year. Only about five per cent of colorectal adenomas are thought to become malignant, and this process could take between five and ten years.

The new case-control study involved 2,028 hospital-based colorectal cancer (CRC) patients and 2,722 population-based controls.

After adjusting the results for potentially confounding factors such as age, sex, location of the tumour, folate status, and certain genotypes, lead author Evropi Theodoratou report: "Moderately strong inverse and dose-dependent associations in the whole sample were found between CRC risk and the intake of dietary and total vitamin B6."

Furthermore, a meta-analysis of published studies supported these results, wrote the researchers. High vitamin B6 intakes were reported to reduce the risk of colorectal cancer by 19 per cent. The protective effect was found to be higher among 55-year-old individuals (1,001 cases compared to 1,010 controls), they added.

"Evidence from larger cohort and experimental studies is now required to confirm and define the anticarcinogenic actions of vitamin B6 and to explore the mechanisms by which this effect is mediated," concluded the researchers.

However, late in 2007, researchers from Tufts University reported that the link between B vitamin intake and the health of the colon and rectum may be more complicated than previously thought.

Writing in the Journal of Nutrition (Vol. 137, pp. 2701-2708), the Tufts researchers stated that moderate deficiency of folate, riboflavin, and vitamins B6 and B12 together may promote the risk of DNA damage and increase the risk of colorectal cancers.

This earlier study focused on the Wnt pathway - a cellular signalling pathway linked to more than 85 per cent of colon cancers - and found that mild depletion of all four B vitamins was needed to promote the risk of tumour formation.

Previously, studies have suggested that folate deficiency alone may promote the risk of colorectal cancer. The new research suggests a more complex interaction.

However, the subject of folate and colorectal cancer is controversial, however, with some studies reporting that the B-vitamin may in fact increase the risk of the disease. On the other hand, other studies have reported protective benefits from folate for colorectal cancer.

Source: Cancer Epidemiology Biomarkers & Prevention
1st January 2008, Volume 17, Pages 171-182, doi: 10.1158/1055-9965.EPI-07-0621
"Dietary Vitamin B6 Intake and the Risk of Colorectal Cancer"
Authors: E. Theodoratou, S.M. Farrington, A. Tenesa, G. McNeill, R. Cetnarskyj, R.A. Barnetson, M.E. Porteous, M.G. Dunlop, H. Campbell