What to watch with MTHFR and gut health?

MTHFR variants (e.g., C677T) reduce enzyme activity, potentially raising homocysteine. Methylfolate is often marketed as personalized supplementation, but robust clinical evidence for general benefit is lacking. The evidence is mostly mechanistic: the biochemical rationale is plausible, yet randomized trials show no clear advantage for cardiovascular or other outcomes. Moreover, high-dose methylfolate can mask B12 deficiency, risking neurological harm. Current guidelines do not recommend routine MTHFR genotyping or supplementation based solely on genotype. A more evidence-based approach is to measure homocysteine: only if elevated should supplementation with folate or methylfolate be considered, and then under medical supervision. Gut health also matters: microbiome imbalances can affect methylation pathways. A microbiome test may provide complementary insights but does not replace clinical judgment. Bottom line: an MTHFR variant alone does not justify methylfolate. Check homocysteine first.