The Omega-3 Index

Background

The Omega-3 Index has been defined as eicosapentaenoic plus docosahexaenoic acids in erythrocytes. Integral part of the definition is a standardized analytical procedure, which conforms to the standards of Clinical Chemistry. This resulted in more than 90 collaborative research projects, concluded and ongoing, and 64 publications so far.

The Omega-3 Index is emerging as a risk factor for fatal and non-fatal cardiovascular events. This standardized analysis of fatty acid patterns adds incremental information to standard risk factor algorithms, and it correctly reclassifies persons from intermediate to high or low risk.

Circumstantial evidence indicates that determining the Omega-3 Index has a therapeutic consequence. Thus, the Omega-3 Index fulfils important criteria for novel biomarkers, set forth by the American Heart Association and others, and compares well to other novel biomarkers. Future results will add precision to the value of the Omega-3 Index in cardiology, and probably expand its application to other areas, like psychiatry and pregnancy.

Reference: The Omega-3 Index as a risk factor for cardiovascular diseases, von Schacky, Clemens, Prostaglandins & Other Lipid Mediators.

 

Statistics Canada Update

Omega-3 Index levels among Canadian adults were higher for women, older people, the Asian population, omega-3-containing supplement users, and people who reported more frequent fish consumption; levels were lower for smokers and obese individuals. When these factors were taken into account, no independent relationships were found between the Omega-3 Index and any CHD-related factor. Information on Omega-3 status will also be available from the 2014/2015 CHMS, thereby allowing for more in-depth analyses using combined data.

An important strength of this study is the direct measure of RBC fatty acids. Assessment of dietary intake alone may be misleading due to physiological and genetic variability in achieving a desired blood level after a fixed dose of omega-3 supplementation. As well, this analysis was able to adjust for many sociodemographic and lifestyle factors. Finally, the weighted data provide estimates representative of the Canadian adult population.

A number of limitations should be considered in interpreting these results. CHMS budget and logistical constraints meant that the RBC fatty acids could be measured only for a subsample of respondents. The small sample size combined with low prevalence, particularly Omega-3 Index levels of 8% or more, required estimate suppression for certain subgroups and limited the power for statistical testing. The lack of significant results may be due to the small sample size, and thus, reduced power to find statistical associations. As future cycles of CHMS data become available, it will be possible to examine relationships in more depth.

The lack of a measure of serving size for the fish consumed meant that it was not possible to measure actual intake. Nonetheless, the associations observed between fish consumption and the Omega-3 Index suggest that the approach had merit. However, owing to the cross-sectional design, it is not possible to establish causation between intakes and the Omega-3 Index.

Reference link to StatCan