Condition
    Moderate Evidence
    Effectiveness 2/5

    Folate (Vitamin B9) for Colorectal Cancer

    Folate appears protective before neoplasia develops and may promote growth of established lesions. High-dose supplementation is not recommended.

    Overview

    Folate appears protective before neoplasia develops and may promote growth of established lesions. High-dose supplementation is not recommended.

    Verdict

    Mixed evidence

    A dual effect that makes timing decisive — and unknowable in an individual.

    How It Works

    Folate supplies one-carbon units for DNA synthesis and methylation. Adequate folate protects normal epithelium from mutation; once a dysplastic clone exists, the same substrate supports its proliferation.

    Dosing & Protocol

    Typical dose

    Recommended dose
    Meet requirements from diet; avoid high-dose supplements without indication
    Expected timeframe
    Trials followed adenoma recurrence over 3-6 years.

    Protocol

    form
    Dietary folate preferred
    notes
    Pregnancy supplementation is a separate, evidence-backed indication
    duration
    n/a
    starting dose
    Meet the RDA from food

    Evidence

    What the studies say

    Observational studies consistently associate higher dietary folate with lower colorectal cancer risk. Randomised trials of folic acid supplementation in people with prior adenomas tell a different story: the Aspirin/Folate Polyp Prevention Study found no reduction in adenoma recurrence and a significant increase in advanced and multiple adenomas. This dual-effect model — protective before, promoting after — is now the mainstream interpretation. Population folic acid fortification has not produced the increases in colorectal cancer incidence that were feared, which suggests the risk relates to high supplemental doses in people with existing lesions.

    Aspirin and folic acid for the prevention of recurrent colorectal adenomas

    Score: 9/10
    2008
    rct
    n=945

    Logan RF, Grainge MJ, Shepherd VC +2 more

    A multicenter, randomized, double-blind trial of aspirin (300 mg/day) and folate supplements (0.5 mg/day) to prevent colorectal adenoma recurrence

    View source

    Safety

    Caveats

    High-dose folic acid can mask B12 deficiency while neurological damage progresses. Avoid doses above 1mg daily without a clinical indication.

    Less likely to help if

    People with a history of adenomas, in whom trials showed possible harm.

    Medical Disclaimer

    The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.