Evidence check: Homocystein in the context of Langlebigkeit

Homocysteine is a sulfur-containing amino acid derivative; elevated levels (hyperhomocysteinemia) are considered a risk factor for cardiovascular disease, neurodegeneration, and premature aging. The evidence for a direct causal role in longevity is moderate: observational studies link high homocysteine to increased all-cause mortality, but randomized controlled trials (e.g., lowering with folate, B12, B6) have not demonstrated a clear lifespan extension. Genetic variants (e.g., MTHFR) influence homocysteine levels, but effect sizes are small. A direct-to-consumer DNA test for homocysteine-related genes does not provide clinically actionable information for longevity—blood measurements and overall context (diet, kidney function, lifestyle) are essential. The evidence supports a moderate association, not proven causality. Beware of marketing that overstates homocysteine as a standalone 'longevity marker.' Safety note: very high levels (>100 µmol/L) require medical evaluation (e.g., cobalamin deficiency).