Comprehensive Analysis of Fatty Acid and Oxylipin Patterns in n3-PUFA Supplements

Supplementing long-chain
omega-3 polyunsaturated fatty acids (n3-PUFA)
improves health. We characterized the pattern of total and non-esterified
oxylipins and fatty acids in n3 supplements made of fish, krill, or
micro-algae oil by LC-MS. All supplements contained the declared amount
of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); however,
their content per capsule and the concentration of other fatty acids
varied strongly. Krill oil contained the highest total n3 oxylipin
concentration (6000 nmol/g) and the highest degree of oxidation (EPA
0.7%; DHA 1.3%), while micro-algae oil (Schizochytrium sp.) showed the lowest oxidation (<0.09%). These oils contain
specifically high amounts of the terminal hydroxylation product of
EPA (20-HEPE, 300 nmol/g) and DHA (22-HDHA, 200 nmol/g), which can
serve as an authenticity marker for micro-algae oil. Refined micro-algae
and fish oil were characterized by NEFA levels of ≤0.1%. Overall,
the oxylipin and fatty acid pattern allows gaining new insights into
the origin and quality of n3-PUFA oils in supplements.