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  • 2009

Folic acid may reduce colon cancer risk

Published on

12 October 2009

Supplements of vitamin B9 (folic acid) may reduce the recurrence of colorectal cancer in people with low levels of the micronutrient, reports a new study.

The randomized controlled trial investigated the effects of vitamin B9 (folic acid) supplementation (1 milligram per day) or placebo on recurrent colorectal tumors over three to six and a half years (1). Overall, no beneficial or detrimental effects were observed as a result of folic acid supplementation. However, among participants with plasma folate levels below 7.5 nanograms per milliliter, folic acid was found to decrease the risk of tumor recurrence by 39 percent.

Contrary to other studies, the researchers found no evidence for an increased risk of advanced or multiple benign tumors (“adenomas”). The study weakens the arguments of opponents of folic acid fortification who cite studies that report potential increases in colorectal cancer risk associated with folic acid.

However, over 30 case-control and prospective cohort studies have reported colorectal cancer risk reductions associated with folate. Folate is found in foods such as green leafy vegetables, chick peas and lentils, while folic acid is the synthetic, bioavailable form of the vitamin used in fortification programs worldwide, as well as in supplements and other fortified foods. On passage through the intestinal wall, folic acid is converted to the naturally circulating form of folate.


  1. Wu K. et al. A randomized trial on folic acid supplementation and risk of recurrent colorectal adenoma. American Journal of Clinical Nutrition. 2009.

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