From the Guidelines
The recommended dose of folic acid for women who are planning or capable of pregnancy is 0.4 to 0.8 mg (400 to 800 μg) per day, as evidenced by the USPSTF recommendation statement 1. This dose has been shown to reduce the risk of neural tube defects in the developing fetus.
- The USPSTF found convincing evidence that supplements containing 0.4 to 0.8 mg of folic acid in the periconceptional period reduce the risk for neural tube defects 1.
- Good evidence from randomized trials suggests that a multivitamin with 0.8 mg of folic acid reduces the risk for neural tube defects 1.
- Observational studies report a reduction of neural tube defects in women taking a supplement with 0.4 mg of folic acid 1. It is essential to start folic acid supplementation at least 1 month before conception and continue daily supplements through the first 2 to 3 months of pregnancy.
- Most studies indicate the need to start folic acid supplementation at least 1 month before conception and to continue daily supplements through the first 2 to 3 months of pregnancy 1. Given that 50% of pregnancies in the United States are unplanned, clinicians should advise all women who are capable of pregnancy to take folic acid supplements.
- Studies also indicate that 50% of pregnancies in the United States are unplanned, and clinicians should therefore advise all women who are capable of pregnancy to take folic acid supplements 1.
From the FDA Drug Label
Except during pregnancy and lactation, folic acid should not be given in therapeutic doses greater than 0.4 mg daily until pernicious anemia has been ruled out. The recommended dose of folic acid is not explicitly stated for all cases, but it should not exceed 0.4 mg daily in non-pregnant and non-lactating patients until pernicious anemia has been ruled out 2.
From the Research
Recommended Dose of Folic Acid
The recommended dose of folic acid varies depending on the individual's risk level and circumstances.
- For women with a low risk for a neural tube defect or other folic acid-sensitive congenital anomaly, a daily oral multivitamin supplement containing 0.4 mg folic acid is recommended for at least 2 to 3 months before conception, throughout the pregnancy, and for 4 to 6 weeks postpartum or as long as breast-feeding continues 3.
- Women with a moderate risk require a diet of folate-rich foods and daily oral supplementation with a multivitamin containing 1.0 mg folic acid, beginning at least 3 months before conception 3.
- Women with a high risk for a neural tube defect require a diet of folate-rich foods and a daily oral supplement with 4.0 mg folic acid for at least 3 months before conception and until 12 weeks' gestational age 3.
- The Belgian Superior Health Council recommends a minimum of 400 micrograms of folic acid or folate supplementation per day from 4 weeks before conception to 8 weeks thereafter 4.
- A study found that a fortification program that delivered 200 micrograms of folic acid daily to women would be effective against neural tube defects and safer for the general population 5.
- The MRC Vitamin Study established that folic acid supplementation (4 mg/day) at the time of conception reduced the recurrence rate of neural tube defects by about 70% 6.
- For women without a history of neural tube defects, the use of 400 micrograms/day of supplemental folic acid is recommended to prevent the occurrence of neural tube defects 7.
Key Considerations
- The quality of evidence in the documents was rated using the criteria described in the Report of the Canadian Task Force on Preventative Health Care 3.
- Women with a gene mutation on the gene coding for the production of methylenetetrahydrofolate reductase have a significantly higher risk of having a miscarriage or a baby with neural tube defects 4.
- A daily dose of 650 micrograms supplemental folic acid normalizes elevated plasma homocysteine levels, which is a risk factor for cardiovascular diseases 7.
- Research is needed to establish the lowest effective dose of dietary folate/supplemental folic acid to optimize homocysteine levels and research on the bioavailability of folate 7.