Why start before pregnancy?
The neural tube, which becomes the brain and spinal cord, closes 3–4 weeks after conception, often before you know you're pregnant. The landmark 1991 MRC trial showed folic acid cut neural tube defect recurrence by about 70%. The USPSTF now recommends that everyone who could become pregnant take 400–800 mcg of folic acid daily, starting at least a month before conception. The U.S. has also fortified enriched grains since 1998.
Food sources and other facts
Leafy greens, asparagus, beans, lentils, and liver are rich in natural folate, though cooking destroys some. Folate deficiency causes anemia with oversized red cells, similar to B12 deficiency, and high-dose folic acid can mask a B12 problem. The CDC says people with common MTHFR gene variants can process regular folic acid, so special "methylfolate" isn't necessary.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Do men need folic acid?
- Most men get enough from a balanced diet; evidence on sperm quality is mixed.
- Can you take too much folic acid?
- Supplement intake above 1,000 mcg a day exceeds the upper limit; don't megadose without a doctor's advice.
Sources reviewed: 2026-10-26
References
- U.S. Preventive Services Task Force. (2023). Folic acid supplementation to prevent neural tube defects: Recommendation statement. JAMA, 330(5), 454–459.
- MRC Vitamin Study Research Group. (1991). Prevention of neural tube defects: Results of the Medical Research Council Vitamin Study. The Lancet, 338(8760), 131–137.
- National Institutes of Health Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals.