The structural protein of HDL — a more reliable marker of protective cholesterol function than HDL-C alone.
ApoA1 is the main structural protein on HDL particles. Just as ApoB counts atherogenic particles, ApoA1 counts protective particles. The ApoB:ApoA1 ratio has emerged as one of the cleanest lipid-based risk predictors — INTERHEART and many subsequent studies show it outperforms LDL-C:HDL-C.
Unlike HDL-C, which can be artificially elevated by alcohol or dysfunctional HDL states, ApoA1 directly counts functional HDL particles.
ApoA1 is influenced by: exercise (aerobic raises it), genetics, estrogen (higher in premenopausal women), alcohol (modest elevation), niacin (classical raiser but now rarely used), and CETP inhibitors. Insulin resistance and metabolic syndrome lower it.
Pair with ApoB — the ratio is the useful number. Target ApoB:ApoA1 <0.6 for primary prevention, <0.5 for established CV risk. Recheck every 6 months alongside ApoB during any cardiovascular-risk-modifying protocol.
Upload any lab PDF and MyProtocolStack maps your values to ApoA1 and 40+ other biomarkers. StackAI interprets the trend in context of your protocol.
Start tracking →Informational only — not medical advice. Reference ranges vary by lab and individual context. Work with a licensed provider to interpret your specific results.