vitamin B6

Recent studies have uncovered an inverse relationship between vitamin B6 levels and risk of colorectal cancer (CRC). A new study published in the American Journal of Clinical Nutrition investigated this relationship in a prospective case-control study of 600 CRC cases and 1200 controls.


Vitamin B6 is part of the water-soluble B vitamin group. It’s active form, pyridoxal 5’-phosphate (PLP) is involved in a variety of functions including macronutrient metabolism, neurotransmitter synthesis, hemoglobin synthesis and gene expression. Additionally, PLP is commonly used as a biomarker to indicate levels of vitamin B6 in the body.

Colorectal cancer (CRC) refers to cancer anywhere between the colon to the rectum. CRC is the third most common type of cancer, resulting in approximately 700,000 deaths globally per year. Symptoms include blood in the stool, weight loss, fatigue and a change in bowel movements. Risk factors include diet, obesity, smoking, lack of physical activity and excess alcohol consumption.

Recent studies have uncovered an inverse relationship between PLP and CRC risk; individuals with higher plasma PLP concentrations displayed up to a 50% lower risk of developing CRC. However, several studies aiming to validate this association have been inconclusive. Additionally, PLP concentration may be confounded by other factors such as a healthy lifestyle, increased physical activity, and lower smoking rates. Thus, the association of PLP concentration and CRC risk may not indicate that vitamin B6 is protective against cancer, but that a healthier population has a lowered risk of cancer.

A new study published in the American Journal of Clinical Nutrition investigated biomarkers of vitamin B6 status to determine their association to CRC risk. Participants were monitored from 1985 to 2009 for plasma levels of PLP as well as novel biomarkers of vitamin B6, pyridoxic acid (PA), 3-hydrocykynurenine (HK), and xanthurenic acids (XAs). By the end of the study, 613 individuals presented with CRC cases, while 1190 remained in the control group.

This study found that the risk of CRC was highest in individuals who had the lowest plasma PLP levels. The authors suggest that the mechanism responsible for this relationship is inflammation – inflammatory biomarkers are increased in CRC and low PLP levels may promote this inflammatory response. Importantly, plasma PLP is strongly influenced by dietary vitamin B6 intake and supplementation. Therefore it is important to consume an adequate amount of vitamin B6, as well as other micronutrients, for optimal health.


Written By: Neeti Vashi, BSc

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