Fortifying food with folic acid may cut down the incidence of the most common type of kidney cancer and a type of brain tumour in children, says a new study. Folic acid fortification reduced the incidence of Wilms\' tumour, a type of kidney cancer, and primitive neuroectodermal tumours (PNET), a type of brain cancer, both of which affect children. \"Our study is the largest to date to show that folic acid fortification may also lower the incidence of certain types of childhood cancer in the United States,\" said Kimberly J. Johnson, assistant professor at the Brown School, Washington University, St. Louis, the journal Paediatrics reports. The study examined the incidence of childhood cancer pre- and post-mandated folic acid fortification. \"We found that Wilms\' tumour rates increased from 1986 to 1997 and decreased thereafter, which coincides exactly with folic acid fortification,\" Johnson says, according to a Washington statement. \"PNET rates increased from 1986 to 1993 and decreased thereafter. This change in the trend does not coincide exactly with folic acid fortification, but does coincide nicely with the 1992 recommendation for women of child-bearing age to consume 400 micrograms of folic acid daily.\" Study authors used the 1986-2008 data from the National Cancer Institute\'s Surveillance, Epidemiology, and End Results Program (SEER), which has collected information on cancer cases in various areas of the US since 1973. The study involved 8,829 children, from birth to age four, diagnosed with cancer. \"Declines in Wilms\' tumours and PNETs in children were detected by multiple analyses of the data,\" Johnson says. \"Importantly, the reduced rates of Wilms\' tumours also were found in a smaller study conducted in Ontario, Canada, that was published in 2011. Julie A. Ross, professor and director of the Division of Paediatric Epidemiology & Clinical Research in the Department of Paediatrics at the University of Minnesota, co-authored the study.