ORIGINAL CONTRIBUTION Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12 Marta Ebbing, MD

FOLATE IS A B VITAMIN ESSENTIALfor nucleotide biosynthesis,DNA replication, and methylgroup supply, and thus for cell growth and repair.1 Folic acid is the syn-thetic form of folate used in vitamin supplements and in fortified foods. Most epidemiological studies have found inverse associations between fo-late intake and risk of colorectal can-cer,2 although such associations have been inconsistent or absent for other cancers.3-8 Experimental evidence sug-gests that folate deficiency may pro-mote initial stages of carcinogenesis, whereas high doses of folic acidmay en-hance growth of cancer cells.9,10 Since 1998, many countries, includ