Folic Acid, Riboflavin, and Colorectal Polyp Biology

Folic acid (a B vitamin) may play a protective role in colorectal health. A double-blind, placebo-controlled study published in Cancer Epidemiology, Biomarkers & Prevention (2007;16(10):2128–2135) investigated how folic acid—alone or combined with riboflavin (vitamin B2)—affects folate status in the colon.

The study included 106 patients with colorectal polyps and 98 healthy controls. Participants were randomized to one of the following:

  • Placebo

  • 1200 mcg/day folic acid

  • 400 mcg/day folic acid

  • 400 mcg/day folic acid + 5 mg/day riboflavin

Researchers measured levels of 5-methyltetrahydrofolate (MTHF)—the biologically active form of folate—in colon tissue, red blood cells, and plasma.

Key findings:

  • Folic acid supplementation increased tissue MTHF in a dose-dependent manner.

  • Red blood cell and plasma MTHF also increased with folic acid.

  • The combination of folic acid + riboflavin produced an additional rise in red blood cell and plasma MTHF in subjects with polyps, but not in healthy controls.

These findings show that folic acid, with or without riboflavin, effectively increases active folate levels in colon tissue and systemic circulation—particularly in people with existing polyps.