About Vitamin B9
Critical for DNA synthesis, cell division, and methylation reactions. 5-MTHF (methylfolate) is the bioactive form that the body can use directly, unlike synthetic folic acid which requires multi-step conversion via the MTHFR enzyme. Around 40–50% of people carry MTHFR gene variants that impair folic acid conversion, making methylfolate the preferred supplemental form. Especially important during pregnancy.
What Vitamin B9 supports
- Essential for DNA synthesis
- Supports red blood cell formation
- Helps regulate mood
How much Vitamin B9 to take
Clinical studies typically use 400–800 mcg of Vitamin B9.
- RDA
- 400 mcg
- Upper limit (UL)
- 1000 mcg
- Effective range
- 400–800 mcg
Forms of Vitamin B9 compared
- L-Methylfolate (5-MTHF)PremiumBypasses the MTHFR conversion bottleneck — works for poor methylators.
- Folinic acidStandardReduced folate. Better than folic acid for MTHFR carriers; 5-MTHF still preferred.
- Folic acidBudgetSynthetic, ~60% conversion rate
Clinical evidence
Strong clinical evidence. Strong evidence for neural tube defect prevention; 40-50% of people have MTHFR variants affecting conversion
NIH Fact Sheet