KCBS_740 SAN FRANCISCO (KCBS) — For decades, pregnant women and women who may become pregnant have been advised to take folic acid to help prevent certain birth defects, but a new study suggests it may be possible to get too much of a good thing.

Very high levels of the vitamin in mothers’ blood have been linked to higher risk of autism in their children.

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“In this study, which was done at the Boston Medical Center, we found that there was a tad elevated levels, which means very high levels of folate, and vitamin B12 were linked with the risk of autism in their kids,” Kripa Raghavan, doctoral candidate at Johns Hopkins Bloomberg School of Public Health, and the study’s lead author told KCBS.

So, how much is too much?

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“At this point it’s still too early to pinpoint the optimum level, or if women need to alter their diet,” Raghavan said.

Raghavan said the supplements are still important for expecting mothers.

“The message we want to be very clear upon here is that during pregnancy, nutrition is important, especially folic acid, and vitamin B12 are very critical, so this by no way questioning that. Women still need to take it, and what we’re trying to do here is flag that. We know deficiency is bad; there is a possibility that excess may also be bad,” she said.

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Raghavan will be presenting her findings in Baltimore, and plans to determine if they are isolated, or representative of the entire U.S.