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Types of Vitamin B9 (Folate): Forms & Bioavailability

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Forms Comparison

FormBioavailabilityBest For
Folic Acid (Synthetic)HighStandard supplementation and food fortification — most studied form; requires DHFR enzyme conversion
L-Methylfolate (5-MTHF)Very HighMTHFR variants and active folate needs — directly bioactive, bypasses conversion; preferred for those with MTHFR C677T or A1298C polymorphisms
Folinic Acid (5-Formyl-THF)HighMedical use — bypass of dihydrofolate reductase, used in methotrexate rescue protocols

Folic Acid (Synthetic)

Bioavailability: High. Best for: Standard supplementation and food fortification — most studied form; requires DHFR enzyme conversion.

L-Methylfolate (5-MTHF)

Bioavailability: Very High. Best for: MTHFR variants and active folate needs — directly bioactive, bypasses conversion; preferred for those with MTHFR C677T or A1298C polymorphisms.

Folinic Acid (5-Formyl-THF)

Bioavailability: High. Best for: Medical use — bypass of dihydrofolate reductase, used in methotrexate rescue protocols.

Full Vitamin B9 (Folate) Guide

References

  1. (). Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. DOI
  2. (). Lowering blood homocysteine with folic acid based supplements: meta-analysis of randomised trials. BMJ. DOI
  3. (). L-methylfolate as adjunctive therapy for SSRI-resistant major depression. American Journal of Psychiatry. DOI