Studies Find that Folate May or May Not Cause Autism

A pregnant woman.
A pregnant woman.

A new study suggests that high levels of folate in pregnant women’s blood might be linked to autism in infants. Folate is regularly found in large quantities (as its synthetic variant, folic acid) in prenatal vitamins.

The study, which calls into question a very common piece of accepted wisdom or advice, is nothing new for pregnant women.

Most women go into pregnancy full of hope and excitement for the future. Though pregnancy can cause some anxiety naturally — it’s normal, especially if it’s your first pregnancy, to fear the unknown — these days, a lot of the anxiety is likely to come from outside. Few things, it seems, are universally agreed upon to be safe or unsafe in pregnancy. Smoking is the obvious one: Everyone agrees that pregnant women should not smoke. But beyond that, what to ingest, in particular, causes a lot of stress, largely because there is little consensus and much conflicting advice.

Fairly innocuous items such as sushi, cheeses, and deli meats are all variously held up as dangerous in small or sometimes any amount. Caffeine either is or is not a “no-no,” depending on the doctor you speak with. Alcohol — which does harm fetuses in large quantities — is probably the most contested of all consumables during pregnancy. Some women abstain completely, while others drink in moderation throughout pregnancy. Both options are supported by doctors: Again, it depends on who you ask.

The issue of folic acid is particularly upsetting, because for decades we’ve relied on previous research that showed that women who take it during pregnancy have lesser instances of certain major birth defects of the brain and spine. So women have been advised to take it during pregnancy for a very long time, and a perusal of a few popular prenatal vitamins show that all of them have folic acid in amounts ranging from 75 percent to more than 100 percent of the daily recommended amount.

So what does the new study show, exactly? The research, conducted by the Johns Hopkins Bloomberg School of Public Health, found that “if a new mother has a very high level of folate right after giving birth – more than four times what is considered adequate – the risk that her child will develop an autism spectrum disorder doubles.” They also found that very high vitamin-B12 levels are “potentially harmful, tripling the risk that her offspring will develop an autism spectrum disorder.” Moreover,  if both levels are extremely high, the risk that a child will develop the disorder increases 17.6 times.

This is all pretty alarming, especially when one considers that folate is often added to breads and cereals in the U.S., and is naturally occurring in fruits and vegetables, in addition to being added to the supplements — prenatal vitamins — that all pregnant women are told to take daily. But there are plenty of reasons not to freak out. “Adequate supplementation is protective: That’s still the story with folic acid,” says one of the study’s senior authors, M. Daniele Fallin, PhD, who presented the findings late last week at the International Meeting for Autism Research in Baltimore. She goes on to say that folate deficiency is known to be detrimental to pregnancy, so women should continue to supplement. However, excessive amounts can also be harmful, that’s what is clear from the study. “Optimal levels,” she said are the goal. In other words, optimal levels are optimal.

Studies: Folate May or May Not Cause Autism