Folic Acid
Also known as: pteroylmonoglutamic acid, folacin, vitamin B9, synthetic folate, PGA
Folic acid is the fully oxidized, synthetic form of folate used in food fortification and most supplements. It is highly bioavailable (about 85 percent with food, near 100 percent fasting) and is the form with the strongest evidence base for periconceptional neural tube defect risk reduction at 400 mcg per day. It supports DNA synthesis, cell division, and homocysteine metabolism. Labels declare it in mcg DFE, where 1 mcg folic acid equals 1.7 mcg DFE, and a 1,000 mcg UL applies to the synthetic form.
Research summary
Reduced by dihydrofolate reductase to tetrahydrofolate and then to 5-MTHF and 10-formyl-THF, the one-carbon carriers for nucleotide synthesis and homocysteine remethylation.
Dosage
Daily amounts, of compound.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 400 mcg | 400–800 mcg | 1,000 mcg | 1,000 mcg |
NIH ODS — UL is 1,000 mcg/day of folic acid from fortified foods and supplements for adults 19+; food folate has no UL
Doses are mcg folic acid. RDA is 400 mcg DFE (600 mcg DFE in pregnancy); DV 400 mcg DFE, so 400 mcg folic acid = 680 mcg DFE (170% DV) and must be labeled as mcg DFE with the folic acid amount in parentheses. NIH ODS reports common adult supplement doses of 400 to 800 mcg folic acid. dose_max_studied is capped at the UL; 2,500 mcg was used in a cardiovascular trial and 4,000 to 5,000 mcg is recommended for women with a prior NTD pregnancy, both under medical supervision. High folic acid can mask the anemia of B12 deficiency, so pair with B12.
Standardization: ≥97% folic acid (USP) or 1% trituration
Source material: synthetic
As supplied: Often used as a 1% trituration on a carrier for premixes (0.1 mg powder per mcg); neat material is used for higher doses. Supplier dependent.
Forms of Folate
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Folic Acid | 400–800 mcg | — | Capsule, Tablet, Powder, Gummy, Liquid, Softgel | low |
| L-5-Methyltetrahydrofolate (L-5-MTHF) | 400–1,000 mcg | — | Capsule, Tablet, Powder, Gummy, Liquid, Softgel | high |
| Folinic Acid (Calcium Folinate) | 400–800 mcg | — | Capsule, Tablet, Powder, Liquid | high |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Yellow-orange; light-sensitive but otherwise stable. Fine in gummies.
Formulation notes
Always pair with vitamin B12 in adult formulas. Interacts with methotrexate, some antiepileptics, and sulfasalazine. Standard prenatal component alongside iron, choline, and DHA.
- Has an upper limit
- Notable drug interactions
Sources
Related ingredients
L-5-Methyltetrahydrofolate (L-5-MTHF)
VitaminL-5-methyltetrahydrofolate is the main circulating form of folate and the form cells use directly for homocysteine remethylation, so it bypasses the MTHFR enzyme step that is less active in people carrying the common 677C>T variant.
Typical: 400–1,000 mcg
Vitamin B12 (Cyanocobalamin)
VitaminCyanocobalamin is the synthetic, highly stable form of vitamin B12 used in most supplements and fortified foods.
Typical: 100–1,000 mcg
Vitamin B12 (Methylcobalamin)
VitaminMethylcobalamin is one of the two coenzyme forms of vitamin B12 that the body uses directly, in this case for the methionine synthase reaction that recycles homocysteine and supports methylation.
Typical: 100–1,000 mcg
Folinic Acid (Calcium Folinate)
VitaminFolinic acid (5-formyltetrahydrofolate) is a reduced, metabolically active folate supplied as its calcium salt.
Typical: 400–800 mcg
Vitamin D3 (Cholecalciferol)
VitaminThe form of vitamin D the body makes from sunlight and the most effective supplemental form for raising blood levels.
Typical: 1,000–2,000 IU