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MTHFR Gene Mutation & Folate: Do You Really Need L-Methylfolate?
Clinical analysis of the MTHFR C677T and A1298C variants: how gene variations affect enzyme efficiency, homocysteine levels, and why 5-MTHF is the preferred supplement form.
By Nourish By Nutrients Editorial Team •
Updated: 2026-11-09
Key Evidence Takeaways:
- The MTHFR gene codes for the enzyme that converts folate into its final bioactive form: 5-methyltetrahydrofolate (5-MTHF).
- The C677T homozygous variant (TT) reduces enzyme activity by roughly 70%, impairing homocysteine breakdown into methionine.
- Carrying an MTHFR variant does NOT mean you cannot have a healthy baby; it means your body processes active L-methylfolate far more efficiently.
- L-Methylfolate is bioidentical, requires zero MTHFR conversion, and does not cause unmetabolized folic acid buildup.
Frequently Asked Questions
How common is the MTHFR gene mutation?
It is very common: roughly 40% to 50% of people carry at least one copy of a variant (heterozygous), and 10% to 14% are homozygous (two copies).
What blood tests should I order if I have MTHFR?
Test your Total Plasma Homocysteine, RBC Folate, and Vitamin B12 (plus MMA) to determine whether your genetic variant is causing functional methylation impairment.