EPA vs DHA

Educational information only, not medical advice. Please talk with your physician before changing your diet, taking supplements or ordering lab tests, especially if you are pregnant, take blood thinners or have a medical condition.

The index adds EPA and DHA together. In the 2018 Framingham analysis, the associations were "generally stronger for docosahexaenoic acid than for eicosapentaenoic acid" ^[11]. The NIH Office of Dietary Supplements fact sheet gives background on both fatty acids and their food sources ^[18]. For most people the practical message is the same either way: eat oily fish, because it supplies both.

Membranes: why the location matters

EPA and DHA are built into the phospholipids that make up cell membranes, which is exactly what the index measures ^[1]. DHA has 22 carbons and 6 double bonds, and those double bonds give it a high degree of conformational flexibility. Once DHA is incorporated into membrane phospholipids, it has been shown to significantly alter basic membrane properties, including acyl-chain order and "fluidity," phase behavior, elastic compressibility, permeability and protein activity ^[4]. This is mechanistic, laboratory-level science. It explains why the index is biologically plausible, but it does not on its own show a health outcome.

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