Folic Acid Supplementation Provided In Utero, But Not After Birth, May Protect Offspring From Colorectal Cancer

"This study provides important insights into the critical role of timing of folic acid intervention in colorectal cancer development and progression. Folic acid may prevent 'new' cancers in the colorectum," said Karen K. Sie, a graduate medical student at the University of Toronto.

The University of Toronto research team had previously demonstrated that folic acid supplementation could promote the progression of the earliest precursor to colorectal cancer. This study focused on whether or not folic acid supplementation in utero could reduce the risk of colorectal cancer in the offspring.

Researchers placed female rats on a control diet or folic acid supplemented diet three weeks prior to breeding, and they stayed on this diet throughout pregnancy and lactation. The male pups from each group were then fed a control or folic acid supplemented diet at weaning.

At five to six weeks, the pups were injected with a colorectal cancer causing chemical, and, at 34 weeks, researchers measured tumor incidence, multiplicity and burden as well as plasma folate, homocysteine and liver folate concentrations.

Pups from mothers on the control diet had a nearly three-fold increased risk of developing colorectal cancer compared with those from rats on folic acid supplementation. Maternal folic acid supplementation significantly decreased the risk of offspring developing colorectal cancer while postnatal folic acid supplementation had no significant effect on the incidence of tumor development.

"Even though folic acid has been successful in reducing neural tube defect rates and is beneficial against some childhood cancers, the potential long term benefits and adverse effects of the drastically increased folate status in the North American population needs to be closely monitored," said Sie. "With the continuing debate and controversy surrounding mandatory folic acid fortification and supplementation, it is critical to determine safe and effective doses and timing of folic acid intervention for colorectal cancer prevention."

This research was presented at the American Association for Cancer Research 2008 Annual Meeting, April 12-16.