Omega-3 index

The index was proposed in 2004 by Harris and von Schacky as the red blood cell content of EPA plus DHA [1]. Its proposers noted that red blood cell fatty acid makeup reflects long-term intake of EPA and DHA [1]. A 2014 review by von Schacky states that he operates Omegametrix, a laboratory for fatty acid analyses; its acknowledgments list research grants from government agencies, AkerBiomarine, Neptune and Fresenius Kabi, and meeting travel costs paid by Sanofi Consumer Health Care [2]. The review adds that red blood cell fatty acid composition has low biological variability, that red blood cell fat is almost entirely phospholipid, and that the composition reflects that of body tissues [2].

The 2004 paper proposed the index as a risk factor for death from coronary heart disease [1]. In the authors' analysis, the index was inversely associated with that risk: an index of 8% or more was associated with the most favorable risk and 4% or less with the least [1]. These reference points come from the index's proposers, not from a trial that tested them.

Laboratory method changes the number. Von Schacky, who operates the Omegametrix fatty acid laboratory, reports that one sample sent to five laboratories offering an omega-3 index gave results that differed by a factor of 3.5, and the standardized method was renamed the HS-Omega-3 Index [2]. A trial's index values are therefore hard to compare with another trial's unless the same method was used.

The same author notes that recent large EPA and DHA trials in the cardiovascular field did not reduce clinical endpoints such as total mortality, and argues that bioavailability and trial design can explain those neutral results [2]. He proposes that future trials recruit people with a low index and give omega-3s to keep them within a preset range, such as 8% to 11% [2]. That is a proposal about trial design from a commercially involved author, not a finding.

On NootropicsWork, the omega-3 index appears as a measure of omega-3 status in study populations, not as a health outcome in its own right.

Phospholipid, subgroup analysis, randomized controlled trial.