Preventive Cardiology, Medizinische Klinik & Poliklinik Innenstadt, Ziemssenstr 1, D-80336 München, Germany and, Omegametrix, Am Klopferspitz19, D-82152 Martinsried, Germany.

The Omega-3 Index is defined as the percentage of eicosapentaenoic acid plus docosahexaenoic acid in red blood cell fatty acids, assessed by a standardized methodology.

Better than fatty-acid compositions in other compartments, the Omega-3 Index represents a person's status in eicosapentaenoic acid plus docosahexaenoic acid. An Omega-3 Index less than 4% is associated with a tenfold risk for sudden cardiac death in comparison to an Omega-3 Index greater than 8%.

Mechanisms of action are plausible and large-scale intervention studies in humans support causality. A low Omega-3 Index may also be a risk factor for coronary artery disease and for complications of congestive heart failure.

Ongoing research will define the value of the Omega-3 Index as a risk factor and treatment parameter more precisely.