Omega-3 Index Test

What is the Omega-3 Index?

The Omega-3 Index is the percentage of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in red blood cell (RBC) membrane fatty acids. Proposed by Harris and von Schacky in 2004, it reflects long-term omega-3 intake over the preceding 90–120 days — the lifespan of a red blood cell — making it a stable, reliable biomarker that is not affected by recent meals.

Unlike plasma or serum omega-3 levels, which fluctuate rapidly with dietary intake, the Omega-3 Index provides a true measure of tissue omega-3 status. It has been extensively validated in prospective studies as an independent risk factor for cardiovascular events and sudden cardiac death.

What does the test measure?

Our Omega-3 Index test quantifies the following from a dried blood spot (DBS) or liquid blood sample using gas chromatography with flame ionisation detection (GC-FID):

• EPA (eicosapentaenoic acid) — expressed as a percentage of total RBC membrane fatty acids
• DHA (docosahexaenoic acid) — expressed as a percentage of total RBC membrane fatty acids
• Omega-3 Index — the sum of EPA% + DHA%, your primary result
• Risk category — mapped to published cardiovascular risk thresholds

Reference ranges

The Omega-3 Index is interpreted against well-established clinical thresholds:

• <4% — High risk: Associated with a significantly elevated risk of fatal coronary heart disease, sudden cardiac death, and adverse cardiovascular events.
• 4–8% — Moderate risk: Below the optimal range. Most individuals in Western populations fall within this zone. Room for improvement through dietary changes or supplementation.
• >8% — Cardioprotective: The target zone. Associated with the lowest risk of cardiac events, comparable to populations with high fish intake such as Japan and South Korea.

Who is this test for?

The Omega-3 Index test is designed for B2B partners who want to integrate validated omega-3 testing into their clinical practice, product offering, or research programme:

• Healthcare professionals: GPs, cardiologists, nutritionists, dietitians, and functional medicine practitioners who monitor patients' omega-3 status as part of cardiovascular risk assessment, dietary counselling, or supplement optimisation.
• Wellness and supplement brands: Companies selling omega-3 supplements who want to offer customers objective before-and-after testing to demonstrate product efficacy and build trust.
• Researchers and academic institutions: Clinical trial investigators, epidemiologists, and population health researchers requiring validated fatty acid biomarker data in study cohorts.

Clinical significance

Cardiovascular health

The Omega-3 Index is the most extensively studied fatty acid biomarker for cardiovascular disease. A meta-analysis of prospective cohort studies has shown that individuals with an Omega-3 Index below 4% have approximately twice the risk of fatal coronary heart disease compared to those with an index above 8%. The biomarker is now recognised as a modifiable risk factor alongside cholesterol, blood pressure, and HbA1c.

Cognitive function

Higher Omega-3 Index values are associated with greater brain volume, particularly in the hippocampus, and with slower rates of cognitive decline in ageing populations. Emerging evidence links low omega-3 status to increased risk of dementia and Alzheimer's disease, making the Omega-3 Index a relevant biomarker in cognitive health screening.

Prenatal and maternal health

DHA is critical for foetal brain and retinal development. Maternal Omega-3 Index values below 5% are associated with increased risk of preterm birth and suboptimal neurodevelopmental outcomes. Testing maternal omega-3 status allows targeted supplementation to ensure adequate DHA transfer during pregnancy.

Inflammation and chronic disease

EPA and DHA are precursors to specialised pro-resolving mediators (SPMs) that actively resolve inflammation. A higher Omega-3 Index reflects greater capacity for inflammation resolution, relevant to the management of conditions including rheumatoid arthritis, inflammatory bowel disease, and metabolic syndrome.

Sample report

Each Omega-3 Index report delivers the combined Omega-3 Index value (EPA + DHA as a percentage of total red blood cell fatty acids), clearly mapped to five clinical risk zones. Reports are delivered via our secure portal within 2–3 working days and include:

• Omega-3 Index score with colour-coded risk zones (Low / Suboptimal / Optimal / Elevated / High)
• Personalised EPA+DHA dose recommendation based on your result
• Results journey chart for tracking progress across repeat tests
• Diet and lifestyle guidance with food-based omega-3 sources
• Clinician-friendly format suitable for patient consultations

For branded or white-label reporting, contact us to discuss customisation options for your organisation.