Can Folic Acid Reduce the Risk of Autism?
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Could taking a vitamin supplement before and during pregnancy help reduce the chances of your child being diagnosed with autism later?
According to a new Norwegian study, yes.
Women who took folic acid supplements before and during early pregnancy were about 40 percent less likely to have a baby later diagnosed with autism. The study was published this week in the Journal of the American Medical Association.
Researchers tracked more than 85,000 Norwegian children born between 2002 and 2008. Doctors asked pregnant women to fill out a questionnaire about supplement use, both before and during their pregnancies, and followed the children for an average of six years. Autistic disorder was present in 0.10 percent of children whose mothers took folic acid, compared with 0.21 percent in children whose mothers did not take folic acid.
"Autism spectrum disorders are a group of developmental disabilities that are often diagnosed during early childhood," explained Dr. Robert Berry, a medical epidemiologist at the Centers for Disease Control and Prevention's National Center on Birth Defects and Developmental Disabilities. The disorder "can cause significant social, communication and behavioral challenges over a lifetime."
There's been a dramatic increase in the prevalence of autism spectrum disorders, now affecting one in 88 children, according to a CDC report released last year. As the NewsHour's Robert MacNeil reported in his "Autism Now," series, the causes of the disorder are "immensely complex" and not entirely understood. It's generally accepted that autism is caused by abnormalities in the brain's structure or function.
Folic acid, a B vitamin, plays a key role in the first days and weeks of embryonic life, before women even know they're pregnant. Folate, the natural form of folic acid, is found in lentils, spinach, black beans, peanuts, orange juice, romaine lettuce and broccoli. Other products, like bread and cereal, are enriched with folic acid. But most people still don't get enough of the vitamin from food alone.
The vitamin is also critical for reducing the risk of spinal bifida and other neural tube defects. But two-thirds of women are not aware that it's important, according to the March of Dimes -- a statistic further complicated by the fact that about a half of all pregnancies are unplanned.
The CDC's Dr. Berry co-authored the accompanying editorial in JAMA. We talked with him about the new research earlier this week.
PBS NEWSHOUR: What did this study find?
DR. ROBERT BERRY: The researchers found that if the mothers took folic acid supplements before and during early pregnancy, there was a lower risk of autism among the mothers who took supplements. The study focused on a large number of children in Norway over the last 10 years. This compared women who chose to take folic acid to women who did not, for whatever reason.
PBS NEWSHOUR: Is there a way of quantifying how much lower of a risk?
DR. ROBERT BERRY: About 40 percent less of a chance to have a baby later diagnosed with autism -- 39 percent exactly.
PBS NEWSHOUR: What exactly is folic acid, also known as folate?
DR. ROBERT BERRY: Folic acid is vitamin B9. It's a water-soluble vitamin that's critical to the function of every single cell in the body. It's an essential nutrient involved in many parts of growth and development, including the creation of DNA.
PBS NEWSHOUR: The study focused on women taking folic acid four weeks before conception and eight weeks after. Why is that time period important?
DR. ROBERT BERRY: We know that folic acid taken during that time period prevents serious birth defects of the brain and spine, because that's when a lot of development of the brain and spine occurs. In the first 28 days after conception, the brain and neural tube structure is formed. So that happens very early, before most women know that they're pregnant. And that's a time when you'd expect other neurodevelopmental processes would benefit from folic acid.
PBS NEWSHOUR: What amount of folic acid were women in this study taking?
DR. ROBERT BERRY: The authors didn't say, except to say they were all under 400mcg. I think that means that most of them were about 200 microgram (mcg) - I think that's the usual amount in multivitamins in Europe.
PBS NEWSHOUR: What is the right amount of folic acid for women who are trying to become pregnant?
DR. ROBERT BERRY: In 1998, the Institute of Medicine made a recommendation that women take 400 mcg of folic acid daily to prepare for pregnancy.
PBS NEWSHOUR: In the U.S., certain foods are fortified with folic acid -- grains, bread, flour -- is that not enough for the typical woman? Do all women need supplements?
DR. ROBERT BERRY: We know the fortification programs provide, on average, about 150 mcg a day. It does not provide the recommended 400 mcg. Only about 25 percent of women are getting that 400 mcg of folic acid a day.
PBS NEWSHOUR: Autism rates have been on the rise for years. Is there a connection to the changes in our diets -- eating less fruits and vegetables rich in folic acid -- and the rise in the autism rates?
DR. ROBERT BERRY: That's not been described as a major risk factor. But there are very few things that are associated with an increased risk of Autism.
PBS NEWSHOUR: Do women with a higher body mass index need more folic acid?
DR. ROBERT BERRY: We're looking into that; we don't have an answer yet. That's an important question that we need to work on.
PBS NEWSHOUR: Have there been other studies looking at this link between autism and folic acid in the early days after conception?
DR. ROBERT BERRY: Yes, there have been two articles published from a large multi-center clinical trial in California, called CHARGE. They start with autism and then ask questions about vitamin consumption. They found the mother's folate status during that early time period in pregnancy was associated with a reduced risk in autism spectrum disorders. This current study confirms that.
PBS NEWSHOUR: Many readers are aware of the link between folic acid and spinal bifida. Are there other neurological-related disorders that are linked to folic acid in early development?
DR. ROBERT BERRY: Yes, there have been a number of papers published on this issue . There's one study on Nepalese children whose mothers were on a randomized trial. They found that those taking folic acid had increased intellectual function when the children were around seven years of age. Another study in India found that at age nine to 10, children with mothers with higher folate levels during pregnancy were associated with better cognitive function scores.
PBS NEWSHOUR: What should women take away from this study?
DR. ROBERT BERRY: I think the most important thing is to encourage women to take 400 mcg of folic acid, especially if they're capable of becoming pregnant. This is another example of good that might come from taking folic acid.
In terms of policy, I think that because the recommendation in the United States is already to take 400 mcg of folic acid, it doesn't have any real implications, necessarily, in the United States. It's possible it might encourage women who don't take folic acid supplements to start taking them before they get pregnant.
Elsewhere in the world, it may be taken into account for people considering fortification programs.