Folic Acid and Neural Tube Defects: Updated Evidence
What it found
In people, folic acid taken around pregnancy was linked to fewer neural tube defects in one large study, and no harms were found for twin births, autism or maternal cancer.
The authors say the new evidence backs up earlier findings.
What they found
Studies in people
Neural tube defects
Three studies with 990 372 people looked at whether folic acid supplements affected neural tube defects. One cohort study found a lower risk when folic acid was taken before pregnancy, during pregnancy, and both before and during pregnancy, but only in the later of two periods studied (2006-2013, not 1999-2005). No other significant benefits were reported overall.
Twin births
One randomized clinical trial with 431 people reported on variations in twin delivery. No significant harm was found.
Autism
Seven observational studies with 761 125 people reported on the incidence of autism spectrum disorder. No significant harm was found.
Maternal cancer
One observational study with 429 004 people reported on maternal cancer. No significant harm was found.
How it was done
They looked at randomized studies and nonrandomized cohort studies in very highly developed countries on folic acid supplements for preventing neural tube defect-affected pregnancies. Twelve observational studies were included, with a total of 1 244 072 people.
What it can’t tell you
- We summarised it from the abstract only.
- Most of the evidence comes from observational studies, which can show a link but cannot prove that folic acid causes the lower risk of neural tube defects.
- The findings apply to very highly developed countries and may not apply everywhere.
The paper
- Title
- Folic Acid Supplementation to Prevent Neural Tube Defects: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force
- Type
- Systematic review
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Viswanathan M, Urrutia RP, Hudson KN, Middleton JC, Kahwati LC (2023). Folic Acid Supplementation to Prevent Neural Tube Defects: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. doi:10.1001/jama.2023.9864PubMed 37526714DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error