Excerpt from: Autism Speaks (click for full article)
Last month, Autism Speaks reported on a study that found reduced risk of autism in Norwegian children whose mothers took folic acid supplements around the time they became pregnant. (See our news story here and the full study here.)
Norway doesn’t require folic acid to be added to food, so prenatal vitamins are the only source of extra folic acid for many pregnant Norwegian women. By contrast, in the United States and Canada, flour and cereal have been fortified with folic acid since 1998.
Therefore, it’s reasonable to wonder whether prenatal folic acid supplements would have a similar effect here. It also raises the question of why autism rates have continued to increase in North America in the years since folic acid fortification of flour and cereals began.