Folate and its preventive potential in colorectal carcinogenesis. How strong is the biological and epidemiological evidence?
Based on a 15-year old hypothesis, it is believed that an adequate ingestion of folate vitamins decreases, whereas a nutritional depletion of folate increases the risk of colorectal cancer. The present article reviews the efforts to provide biochemical and epidemiological evidence for folate as a chemopreventive agent against colorectal carcinogenesis. BIOLOGICAL EVIDENCE: Tetrahydrofolates govern the intracellular one-carbon metabolism and account for proper DNA biosynthesis and macromolecular modification. Numerous experimental studies traced different molecular pathways and tried to link folate depletion with DNA instability and/or mutagenesis. However, none of the proposed underlying molecular mechanisms appear clearly defined. EPIDEMIOLOGICAL EVIDENCE: Numerous case-control and prospective studies have been conducted on folate and colorectal cancer, which all together miss a clinical bottom line. The recommendation of folate intake to prevent colorectal cancer is therefore not evidence-based.
Bollheimer
L Cornelius
LC
Department of Internal Medicine I, University of Regensburg, 93042 Regensburg, Germany. cornelius.bollheimer@klinik.uni-regensburg.de
Buettner
Roland
R
Kullmann
Anja
A
Kullmann
Frank
F
D016022:Case-Control Studies; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D019317:Evidence-Based Medicine; D005492:Folic Acid / Q000737:chemistry / Q000378:metabolism / Q000627:therapeutic use*; D005494:Folic Acid Deficiency / Q000150:complications; D006801:Humans; D016896:Treatment Outcome
D005492:Folic Acid