Omega-3 Index Plus

The Omega-3 Index Plus is an extended version of the standard Omega-3 Index, measuring the percentage of EPA and DHA omega-3 fatty acids in the membranes of your red blood cells. As with the standard Index, because red blood cells live for around 120 days, the result reflects your average omega-3 intake over the previous two to three months, a much more stable picture than any one-day snapshot. Omega-3 fatty acids are essential building blocks your body cannot synthesise itself; you must obtain them from oily fish, algae, or supplementation. They are incorporated directly into your cell membranes, keeping them flexible, supporting healthy inflammatory responses, and helping the electrical signalling in your heart and brain.

The "Plus" version is reported when the test is included in a broader panel. Interpretation is identical to the standalone Omega-3 Index: an index above 8 per cent is generally considered cardioprotective, 4 per cent or below is associated with higher cardiovascular and inflammatory risk, and most UK adults sit in the 4–6 per cent range. The target range is based mainly on observational evidence linking higher omega-3 membrane status to fewer sudden cardiac events; higher levels have also been linked with better cognition and lower markers of inflammation.

Like the standalone Index, your level is driven primarily by dietary omega-3 intake. Oily fish is the main dietary source, and EPA and DHA supplements are an alternative for people who do not eat fish. The amount needed to reach the target range varies between people. Changes take two to three months to reflect fully in cell membrane composition, so persistence matters. Your GP or a registered dietitian can advise on the most suitable approach for you.