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Marker · Educational ranges, not diagnosis

Omega-3 index

Also called EPA plus DHA percent, RBC omega-3.

The share of EPA and DHA in red-blood-cell membranes. It is a status marker for oily-fish intake and for EPA/DHA capsules, not a diagnosis of heart disease.

Read this first

  • Coach, not doctor. Aaron Cuha is a coach, not a doctor. No clinical credential is claimed for him, or for these pages. A number on a panel is a conversation starter with a clinician, not a DIY diagnosis. Nothing here is a prescription, a protocol, or a reason to start or stop a medicine. Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.
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Why a longevity audience asks

Harris proposed it as a coronary-risk conversation number. Later pooled cohorts still tie a higher index to lower coronary death. Randomised outcome trials of high-dose omega-3 then split, so the index is a food-and-capsule marker, not a promise that raising it prevents events.

How a coach reads it

The owner's published conversation target on /supplements is 8 to 10 percent. Papers that introduced the index discussed roughly 8 percent and above as the desirable band and under 4 percent as the high-risk band. Those bands are literature conversation ranges, not a diagnosis. Your lab's reference interval is the one your clinician reads.

Units on this page: percent of red-cell fatty acids

When it is low

Usually means you eat little oily fish and are not taking a meaningful EPA/DHA dose. It does not, by itself, say you will have a heart attack.

When it is high

Usually means diet or capsules are landing. High-dose EPA has a real atrial-fibrillation discussion in outcome trials. That is a clinician conversation, not a reason to chase a higher index forever.

Easy ways to misread it

  • Plasma EPA/DHA is not the same test as the red-cell index.
  • A fish-oil capsule is not icosapent ethyl. REDUCE-IT does not transfer to the bottle on the shelf.
  • Do not start or stop a statin, anticoagulant, or heart medicine off this number.

What to ask a clinician

Ask for an omega-3 index, or red-cell EPA and DHA. Say if you already take fish oil so the draw is timed honestly.

Related supplements

Related when-playbooks

Sources on this page