Consumption of Vitamin B6 Reduces Fecal Ratio of Lithocholic Acid to Deoxycholic Acid, a Risk Factor for Colon Cancer, in Rats Fed a High-Fat Diet

To examine the effect of supplemental dietary vitamin B-6 on the colonic luminal environment, growing male rats were fed a high-fat diet containing 1, 7, or 35 mg pyridoxine HCl/kg diet for 6 wk. Food intake and growth were unaffected by the dietary treatment. Supplemental dietary vitamin B-6 significantly reduced the production of a fecal secondary bile acid. lithocholic acid (the most toxic secondary bile acid and a risk factor for colon cancer), and markedly reduced the ratio of lithocholic acid to deoxycholic acid (a less toxic secondary bile acid) in feces (p<0.05). Increasing dietary vitamin B-6 increased fecal mucin levels (a marker of intestinal barrier function) in a dose-dependent manner (p<0.05) but did not affect fecal immunoglobulin A levels (an index of intestinal immune function). Cecal levels of organic acids were not significantly affected by supplemental dietary vitamin B-6. These results suggest the possibility that dietary vitamin B-6 affects the colonic luminal environment by altering the production of secondary bile acids and mucins.