Earlier is much better for prenatal multivitamins, a new study published in Epidemiology confirms. Mothers of children with autism or related autism spectrum disorders were much less likely than mothers of children without autism to have taken prenatal vitamins three months before conception and during the first month of conception. Taking high-quality, folate-rich prenatals before getting pregnant may help reduce risk of these increasingly common disorders by 40 percent, researchers suggest.

Working with the Charge project (California Autism Risks from Genetics and Environment), scientists recruited 532 children with autism and related disorders and compared them with 278 children who were considered to be developing normally. Using blood samples, they deducted that mothers and children with gene variants that affect folate metabolism—and who did not take prenatals preconception—the risk for autism increased by as much as seven times!

Folate, also known as vitamin B9 and folic acid (a synthetic form of folate), can help prevent neural tube defects, such as spina bifida, in developing fetuses (although how it works is still unclear)—hence it's a standard in prenatal multis. Since 1998, the FDA as also mandated folic-acid fortification for grain products, partly in an attempt to address that early window of increased birth-defect risk in children of mothers who didn't yet realize they were pregnant (and weren't yet taking prenatals). Since 1998, U.S. birth defects have dropped by 19 percent.

Recent research has suggested that children with autism may have altered folate or methionine metabolism, but results remain inconclusive.

Folic acid in the news

In other folate-related news, some experts have suggested that high doses of synthetic folic acid (from grain products and other folic acid–fortified foods) might increase the risk of colorectal cancer—prompting Prevention magazine to go so far as to run the headline “Is Your Breakfast Cereal Giving You Cancer?"

“I've reviewed the studies that were used as the basis for all this speculation and found that the data was very weak, to say the least,” says Robert Rountree, MD, Delicious Living's medical editor. “The good news is that four new published studies have carefully examined data from large clinical trials and not one of them found the slightest indication that synthetic folate supplements increased cancer risk.” Read abstracts of new studies here and here.

Among some nutrition researchers, an ongoing debate does continue as to whether natural folate (found in foods such as leafy green vegetables, fruit, dairy, and liver) is easier for the body to metabolize than synthetically derived folic acid, which is the main source of this B vitamin for most Americans, via fortified foods. On the other hand, according to the National Institutes of Health, synthetic folic acid has a simpler chemical structure than natural folate and is absorbed more easily by the body.

If you're concerned about folate metabolism, look for a prenatal multivitamin (or a regular multi) with a natural form of folate.