What to watch with MTHFR and fatigue?

MTHFR variants (C677T, A1298C) reduce the enzyme's ability to convert folic acid into active methylfolate, potentially raising homocysteine levels, which is associated with fatigue in some studies. However, the evidence linking MTHFR directly to fatigue is mixed; many individuals with variants are asymptomatic. Practical steps: test homocysteine, vitamin B12, and folate levels. If homocysteine is elevated, supplementation with methylfolate (not folic acid), methylcobalamin (B12), and pyridoxal-5-phosphate (B6) may help. Caution: high-dose folic acid can accumulate unmetabolized in blood if MTHFR is impaired. Fatigue has many causes (iron deficiency, thyroid, sleep apnea, stress). A consumer DNA test like MyBody-X can reveal MTHFR status but is screening only, not diagnostic. Always consult a physician for personalized advice. Evidence: mechanistic and observational; not strong enough for universal recommendations.