MTHFR C677T homozygous: building a methylation support stack from genomics data
Using raw genomics data to understand MTHFR variants and build a targeted supplementation protocol for impaired methylation.
When I got my raw genomics data back and ran it through a few analysis tools, one variant jumped out immediately: MTHFR C677T homozygous (rs1801133 T/T). This is one of the most well-studied functional polymorphisms in human genetics, and being homozygous for the T allele means my MTHFR enzyme operates at roughly 30% efficiency compared to the wild type.
What MTHFR actually does
MTHFR (methylenetetrahydrofolate reductase) is the enzyme responsible for converting 5,10-methylenetetrahydrofolate into 5-methyltetrahydrofolate — the active form of folate that your body actually uses. This active folate is essential for:
- Methylation — the process of adding methyl groups to DNA, proteins, and neurotransmitters
- Homocysteine metabolism — converting homocysteine back to methionine
- Neurotransmitter synthesis — particularly serotonin, dopamine, and norepinephrine
- DNA repair and synthesis
When MTHFR is impaired, the downstream effects ripple through multiple systems.
The stack
After several months of research, lab work, and iterative testing, here’s the supplementation protocol I’ve settled on:
- Methylfolate (5-MTHF) — 800mcg daily, bypassing the broken enzyme entirely
- Methylcobalamin (B12) — 1000mcg sublingual, works synergistically with methylfolate
- Riboflavin (B2) — 400mg, MTHFR is a flavoprotein and B2 is its cofactor
- TMG (Trimethylglycine) — 500mg, provides an alternative methylation pathway
- NAC — 600mg, supports glutathione production (often depleted with poor methylation)
Monitoring
The key labs to watch:
- Homocysteine (target: below 8 µmol/L)
- Methylmalonic acid (B12 status)
- RBC folate (not serum folate — it’s misleading with supplementation)
Not medical advice. This is my personal n=1 protocol based on my specific genetics. Talk to a practitioner who understands nutrigenomics.