Folic acid supplementation of grain products -- mandated in the U.S. since 1998 -- is associated with a reduced incidence of a few, though not all, childhood cancers, retrospective analyses found. The incidence rates of all early childhood cancers after folic acid supplementation began did not differ significantly from earlier rates, with an incidence rate ratio (IRR) of 1.01 (95% CI 0.96 to 1.06), according to Amy M. Linabery, PhD, from the University of Minnesota in Minneapolis, and colleagues. Rates were lower, however, for Wilms tumor (IRR 0.80, 95% CI 0.68 to 0.95, P