“Vitamin B9 (methylfolate)?”Here!folate, L-5-methyltetrahydrofolate (5-MTHF)
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As a supplement
Talk to your doctor or pharmacist.
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The naturally circulating, already-active form of folate (vitamin B9), sometimes used in supplements instead of synthetic folic acid.
Why it’s used
Taken to support folate status, particularly by people planning pregnancy or those seeking a form some believe is more readily used by the body than folic acid.
What the evidence is for
correcting folate deficiency and reducing neural tube defect risk in pregnancy.
What the evidence says
NIH ODS describes folate as established for correcting deficiency and for reducing the risk of neural tube defects when adequate folate status is present before and during early pregnancy. Most of the large supporting trials used synthetic folic acid rather than methylfolate directly; methylfolate has been studied mainly for bioavailability and for people with reduced ability to convert folic acid, with a smaller body of direct outcome research.
Dose studied
400–1000 mcg — adult RDA up to the tolerable upper intake level for folic acid forms, per NIH ODS.
Context
NIH ODS lists an adult RDA of 400 micrograms dietary folate equivalents per day, rising to 600 during pregnancy, with a tolerable upper intake level of 1,000 micrograms per day for the synthetic forms.
Rumors
Preventing the neural tube defects folate deficiency causes in early pregnancy, and correcting its megaloblastic anemia — weakness, fatigue, trouble concentrating and breathlessness.
Supports — establishedhealth and safety evidence
Studied in: women of childbearing age / pregnant women.
Measured as an outcome.
- Folate - Health Professional Fact Sheet (Regulatory) · Funding not checked
How much is a reference amount
- 400 mcg DFE a dayfor adults 19 and over · Recommended Dietary Allowance
Upper limit 1,000 mcg a day, from supplements and fortified foods — it does not apply to the nutrient as it occurs in food and only to synthetic folic acid — not to folate as it occurs in food.
The RDA is in dietary folate equivalents; the UL is in mcg of SYNTHETIC folic acid from supplements and fortified foods only — the FNB set no UL for folate from food. A label stating plain mcg cannot be compared to the DFE figure without knowing the form.
Every applicable line is shown because we don’t know which one is yours, and a reference intake is a target for a population, not a threshold for harm.