The Omega-3 Index: A New Risk Factor for Cardiovascular Death

Background

Drs. William S. Harris and Clemens von Schacky published this foundational paper in Preventive Medicine (PMID: 15208005), proposing the Omega-3 Index as a new cardiovascular risk factor.

Study Design

Review and synthesis of evidence linking red blood cell EPA+DHA content to cardiovascular outcomes, with proposal for standardized measurement and interpretation.

Key Findings

Omega-3 Index definition: EPA + DHA as percentage of total RBC fatty acids

Risk stratification:

Omega-3 Index	Risk Category	Population Examples
<4%	High risk	Most Western populations
4-8%	Intermediate	—
>8%	Low risk	Japan, parts of Scandinavia

Key evidence:

• •70% reduction in sudden cardiac death risk comparing >8% vs. <4%
• •Strong correlation with cardiac tissue omega-3 content
• •More stable than plasma levels (reflects 120-day intake)

Mechanistic Insights

RBC membrane EPA+DHA content reflects:

1. •Cardiac membrane composition (arrhythmia protection)
2. •Long-term omega-3 status (not acute intake)
3. •Integration of diet + supplementation + genetics

Higher membrane omega-3 improves:

• •Electrical stability (anti-arrhythmic)
• •Endothelial function
• •Platelet aggregation
• •Triglyceride levels

Clinical Implications

The Omega-3 Index provides a measurable, modifiable risk factor. Testing is commercially available. Target ≥8% achievable through fatty fish consumption (2-3 servings/week) or supplementation (1-2 g EPA+DHA/day).

Metabolic Health Perspective

The Omega-3 Index integrates into metabolic optimization as a key marker. Unlike LDL, it responds reliably to dietary intervention. Achieving ≥8% supports cardiovascular, metabolic, and brain health.