Folic acid supplementation throughout pregnancy reduces lead exposure and autistic behavior in children

It is an established fact that pregnant women should supplement with folic acid, as it reduces the risk of the baby developing neural tube defects in the brain and spinal cord. According to a new Canadian study, folic acid supplementation may also reduce the risk of the child developing neurological damage and autistic behavior caused by lead exposure. It is crucial for pregnant women to get enough nutrients to support fetal development. Also, they should try to avoid environmental toxins as much as possible.

Folic acid (vitamin B9, folate) is essential for DNA and amino acid synthesis, cell division, blood formation, and energy levels. Since folic acid plays a key role in fetal growth and neurological development, pregnant women are at high risk of becoming deficient.
A lack of folic acid in early pregnancy increases the risk of neural tube defects such as spina bifida, which can lead to heart defects, severe disabilities, or stillbirth. Studies show that a folic acid deficiency can impair brain development, including neuropsychological development, which accelerates in the later stages of pregnancy.
Lead and other environmental toxins can also harm the neurological development of the unborn child. Common sources of lead exposure include industrial pollution, air and water pollution, tobacco smoke, batteries, cosmetics, road dust, old paint, ammunition, colored glass, jewelry production, and soldering. Although the transition to lead-free gasoline has generally lowered lead levels, exposure can still be excessive - and pregnant women are particularly vulnerable.
Lead is a heavy metal that cannot be broken down in the body. When it accumulates, it can cause serious damage to the nervous system, liver, kidneys, and hormone-producing glands.
While folic acid supplementation appears to reduce the harmful effects of various chemicals during pregnancy and lower the risk of autistic behavior in the child, it has not previously been studied in relation to lead exposure specifically.

Study methods and findings

The aim of the new study was to examine pregnant women’s folic acid intake, blood levels of active folic acid (measured as methylfolate), blood lead levels, and whether these were associated with autistic behavior in their children.
Researchers used data from the large Canadian MIREC study (Maternal-Infant Research on Environmental Chemicals) conducted between 2008 and 2011, which investigates pregnant women, their children, and environmental toxin exposure. Nearly 2,000 pregnant women met the inclusion criteria.
Using a standardized assessment called the Social Responsiveness Scale-2 (SRS-2), researchers identified 601 children aged 3-4 years who exhibited autistic behavior. Higher SRS-2 scores indicated more pronounced symptoms.
Lead levels and total methylfolate concentrations were measured in the women’s blood during the first and third trimesters. Their intake of folic acid supplements was also estimated.
The findings showed that higher lead levels in the third trimester - when brain development is especially rapid - were significantly associated with increased SRS-2 scores, particularly when methylfolate concentrations were low and folic acid intake was below the recommended 400 micrograms per day. A similar but weaker association was found in the first trimester.
The researchers concluded that recommended folic acid supplementation may help reduce the link between lead exposure during pregnancy and the child’s risk of developing autistic behavior.
The new study was published in Environmental Health Perspectives and supports earlier research showing that the association between autism and exposure to pesticides, air pollution, and phthalates (used as plastic softeners) is stronger when the mother does not take the recommended folic acid supplements during pregnancy.

Facts about vitamin B9 / folic acid / folate and pregnancy supplements

• Foods such as liver, vegetables, and eggs contain vitamin B9 in the form of folate
• Most dietary supplements contain folic acid, the synthetic form of the vitamin
• Both folate and folic acid must be activated before the body can use them
• In the blood, folic acid is measured as the active methylated form, methylfolate (5-MTHF)
• Pregnant women who take 400 micrograms of folic acid daily during the first trimester reduce the risk of neural tube defects in the baby’s brain and spine
• Pregnant women who take 400 micrograms of folic acid daily throughout the entire pregnancy reduce the risk of the child developing autistic behavior due to lead exposure and other environmental toxins

References:

Joshua D et al. Combined Exposure to Folate and Lead during Pregnancy and Autistic-Like Behaviors among Canadian Children from the MIREC Pregnancy and Birth Cohort. Environmental Health Perspective, 2024

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