Is Folic Acid a Risk Factor for CRC?

Epidemiologic studies of dietary folate intake have generally indicated an inverse relationship with colorectal cancer (CRC) risk. In the U.S., folic acid, a form of folate, is consumed through supplementation with vitamins and fortification of flour. Recently, the nature of the association between folate and CRC has been in doubt based on results of a randomized controlled trial showing an increased risk for advanced adenomas in a high-risk group taking folic acid supplements (JW Gastroenterol July 6 2007) as well as a documented uptick in CRC incidence after the fortification of flour began in the late 1990s (Cancer Epidemiol Biomarkers Prev 2007; 16:1325).

To examine whether folic acid increases the risk for CRC, researchers evaluated dat…