Folic acid supplementation may lower risk of certain childhood cancers

Folic acid fortification of US grain products may be lowering rates of certain kidney and brain cancers in children but does not appear to be causing childhood cancer rates to increase, according to findings from a study published online May 22 in the journal Pediatrics.

According to the researchers, the US Public Health Service recommended in 1992 that women of childbearing age consume 400 µg of folic acid daily, based on evidence that maternal prenatal consumption of folic acid significantly reduces the incidence of neural tube defects and some congenital abnormalities. FDA subsequently ordered supplementation in grain products by January 1, 1998.

Because of concerns over the vitamin's potential to contribute to cancer, researchers, led by Amy Linabery, PhD, a postdoctoral fellow in the University of Minnesota's Division of Pediatric Epidemiology and Clinical Research, and Kimberly Johnson, PhD, assistant professor in the Brown School at Washington University in St. Louis, compared data for incidence of childhood cancers before and after fortification began using statistics from the National Cancer Institute between 1986 and 2008.

The investigators identified 8,829 children aged 0 to 4 years who were diagnosed with malignancies. There were 3,790 and 3,299 estimated to be in utero during the pre- and postfortification periods, respectively. Although the investigators did not observe reductions in the incidence of most childhood cancers after the mandatory folic acid fortification began, they did note declines in rates of Wilms tumor and primitive neuroectodermal tumors incidence through multiple analytic strategies.

The investigators commented that firm conclusions about the isolated effects of folic acid supplementation are difficult to draw because of concurrent trends during the study period, such as increases in other preventive factors, increasing birth weight that has been linked to increased risk for a number of childhood cancers, and shifting classification schemes coupled with improvements in tumor classification.

“These results must be interpreted cautiously because they are not adjusted for multiple comparisons, and we would expect statistically significant associations just by chance in ∼5% of malignancies using a = .05,” the authors wrote. “Alternative study designs, such as prenatal feeding experiments in animal models, are required to rule out other explanations, confirm causal relationships, and elucidate mechanisms.”