Summary

A new report from the Physicians’ Health Study suggests that vitamin B6 helps reduce the risk of colorectal cancer. Blood levels of the vitamin were measured and those with the highest levels had a 53% reduced risk.

Moreover, the protection is independent of levels of other B vitamins and may work through reducing oxidative stress or some other mechanism still to be discovered.

Introduction

The role of vitamins in cancer prevention is controversial, with some studies showing a protective effect from fruit and vegetables or supplements and others contradicting the findings. There is already some evidence that vitamin B6 may protect from colorectal cancer but research has not, so far, been able to establish whether other B vitamins are also involved. Vitamin B6 is known to be vital for DNA production and its lack might lead to the kind of DNA damage that is associated with cancer.

What was done

Researchers at Brigham and Women’s Hospital and Harvard Medical School looked at data from the long-running Physicians’ Health Study, which involves more than 22,000 male doctors and aims to look at many factors influencing long term health. In the current study, blood samples from 197 men with colorectal cancer were compared with those from 371 matched cancer-free controls.

The researchers measured levels of pyridoxal 5'-phosphate (PLP) which is the active form of vitamin B6. Folate, another B vitamin, was also measured along with vitamin B12, markers for inflammation, and other colorectal cancer risk factors like consumption of red meat and body mass index.

What was found

Men with high PLP levels had a 53% lower risk of colorectal cancer compared to those with low PLP levels. The effect of plasma PLP on colorectal cancer risk stood independent of other B vitamins that are involved in DNA modification or production, and also of inflammation.

What this study means

The mechanism by which vitamin B6 reduces colorectal cancer risk may not be related to DNA damage. Some ideas put forward by the researchers are that vitamin B6 might block the spread of cancer cells or of the formation of blood vessels that can feed a tumor. It may also reduce oxidative stress. Many people have low levels of vitamin B6 and thus may be putting themselves at risk. Fortified cereals or supplements could help boost your intake – but high dose supplements of B6 should only be taken under the direction of a qualified practitioner.

Source

Lee JE, Li H et al Prospective study of plasma vitamin B6 and risk of colorectal cancer in men Cancer Epidemiology Biomarkers and Prevention April 2009; Volume 18 Issue 4.