Homocysteine

What it isHomocysteine is a sulfur-containing amino acid produced as a byproduct of methionine metabolism. It's recycled back to methionine (using folate and B12) or shunted to cysteine (using B6).

DoesReflects how efficiently the methylation cycle is running. When methylation enzymes lack their cofactors, homocysteine accumulates.

GoodLow homocysteine indicates fluent methylation and adequate B vitamin status.

BadElevated homocysteine damages the endothelium, drives oxidative stress, and predicts cardiovascular events, stroke, and brain atrophy with dementia.