High folate levels in pregnancy may increase risk of autism

May 12, 2016 Providence Health Team

A new study found that excessive amounts of folic acid and vitamin B12 during pregnancy may elevate the risk for autism. Folic acid has long been known to prevent birth defects of the brain and spinal cord, called neural tube defects. Some studies also suggest it can prevent heart defects and cleft palate.

The researchers, led by Ramkripa Raghavan, Johns Hopkins Bloomberg School of Public Health, studied 1,391 pairs of mothers and children in Boston between 1998 and 2013.  Those mothers who measured for very high levels of folate in their blood shortly after giving birth were twice as likely to have a child who developed an autism spectrum disorder (ASD) than new mothers with normal levels of the vitamin.

The study also showed that women with very high levels of B12 in their blood after giving birth were three times more likely to have a child with ASD compared to mothers with normal levels of the vitamin.

However, taking a multivitamin during pregnancy was associated with lower autism risk overall.  

The study requires further investigation and does not change any of the current guidelines for supplementation during pregnancy. However, it suggests a need for expecting mothers to get optimum levels of folate and B12 for best health effects, while also avoiding excess amounts of the nutrients.

Folate: What's the right amount?

Health care providers still recommend this critical nutrient to help defend against birth defects. Currently, the American Congress of Obstetricians and Gynecologists continue to recommend 400 micrograms (mcg) daily to help prevent birth defects to the baby's brain and spine.

Folate is a naturally occurring form of a water-soluble B vitamin and it is present in many foods. Folic acid is the synthetic form of this vitamin. According to the National Institutes of Health, foods that contain folate include:

  • Fortified grains, including fortified cold cereals, enriched flour products such as bagels, cornmeal and rice
  • Grain-based products and corn masa flour, used to make corn tortillas and tamales
  • Vegetables, especially asparagus, Brussel sprouts, and dark green leafy vegetables such as spinach and mustard greens
  • Citrus fruits and juices, especially oranges and orange juice
  • Nuts, beans and peas, such as peanuts, black-eyed peas and kidney beans

The benefits of vitamin B12

According to the National Institute of Health, B12 deficiency in infants has been linked to failure to thrive, megablastic anemia, movement problems and developmental delays. Common foods with vitamin B12 in them include:

  • Beef liver and clams (best sources)
  • Fish
  • Meat
  • Poultry
  • Eggs
  • Milk and other dairy products
  • Fortified products, such as some breakfast cereals and nutritional yeasts

More research is needed to find the optimal levels for both folate and vitamin B12 to be taken during pregnancy.

Always check with your pediatrician, nurse midwife or OB/GYN about the best diet and prenatal supplements for you. Avoid going over dosage recommendations, unless prescribed by a qualified health care provider, and review all your supplements with your provider.

Need a doctor or OB-GYN? You can find a Providence provider here.

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