What it measures
Omega-3 index = (EPA + DHA) as a percentage of total fatty acids in red blood cell membranes. Reflects 3-4 month dietary average, RBC membrane composition stabilizes over time.
Optimal ranges
- >8%: Optimal (associated with lowest cardiovascular risk)
- 4-8%: Suboptimal
- <4%: High risk
US population status
Average US adult omega-3 index: 4-6%. Reflects low fish consumption and high omega-6 from processed oils. Most adults benefit from supplementation.
Health outcomes
Higher omega-3 index correlates with:
- Reduced cardiovascular events
- Reduced sudden cardiac death
- Slower cognitive decline
- Lower depression rates
- Reduced inflammation
- Better visual function
Supplementation
- EPA + DHA 2-4 g daily for most adults
- Higher doses for high triglycerides or specific conditions
- Take with fat-containing meal
- Quality matters: third-party tested for purity
- Liquid forms or smaller capsules for high doses
- Krill oil and algae oil are alternatives
The clinical pearl: Omega-3 index is one of the most modifiable cardiovascular risk markers. Most adults can move from 4-5% to 8%+ in 4-6 months with appropriate supplementation. Test baseline; supplement; re-test.
Bottom line
Omega-3 index is the practical EPA+DHA marker. Optimal >8%. Most adults are below optimal. Supplementation moves it substantially. Higher index correlates with better cardiovascular and cognitive outcomes.