An essential B vitamin critical for DNA synthesis, methylation, and neural tube development. L-methylfolate (5-MTHF) is the bioactive form, bypassing MTHFR polymorphisms that affect 40-60% of the population.
Prevents neural tube defects
STRONGRequired for proper DNA synthesis during rapid cell division in embryogenesis; deficiency causes spina bifida and anencephaly
Reduces homocysteine levels
STRONGMethylfolate donates methyl group to convert homocysteine to methionine via methionine synthase (with B12)
May augment antidepressant therapy
MODERATEL-methylfolate is required for synthesis of serotonin, dopamine, and norepinephrine via BH4 pathway
Supports healthy cell division
STRONGEssential cofactor for thymidylate synthase in DNA synthesis; deficiency leads to megaloblastic anemia
COMMON: 400-800 mcg DFE
TIMING: Any time, daily
L-methylfolate (5-MTHF) bypasses MTHFR C677T mutation. Folic acid is synthetic and requires enzymatic conversion. 1mg (1000mcg) UL for folic acid specifically (can mask B12 deficiency). Methylfolate does not have a defined UL.
Safety
Moderate interactions. Monitoring, timing separation, or dose adjustment may be required.
Methotrexate
Folic acid competes with methotrexate for folate receptors.
Source: FDA label
Phenytoin (Dilantin)
Folic acid may reduce phenytoin levels.
Source: Clinical pharmacology
5-Fluorouracil (5-FU)
Folic acid (as leucovorin) is sometimes given with 5-FU to enhance its effect.
Source: Oncology standard
Educational information only. This is not medical advice. These statements have not been evaluated by the FDA. Talk to your prescriber before starting, stopping, or combining any supplement with prescription medication.