Comparative membrane incorporation of omega-3 fish oil triglyceride preparations differing by degree of re-esterification: A sixteen-week randomized intervention trial

Abstract

Background Fish oil is routinely concentrated into unmodified triglycerides, or trans-esterified into an ethyl ester form. Re-esterification of the ethyl ester form yields re-esterified triglycerides (rTG), which are reportedly more bioavailable than ethyl ester forms. However, the fidelity of the re-esterification process may yield variable triglyceride forms, with only 55–60% being rTG. Objective To determine whether the blood lipidomic response to supplementation with two rTG supplements, varying by degree of re-esterification, would differ between treatments. Design This was a double-blind, parallel-design, single-center, 128-day study with sixty young, healthy subjects randomized into two groups. One group received a >95% rTG (Ultimate Omega®), as 1,000 mg capsules containing 325 mg eicosapentaenoic acid (EPA) and 225 mg docosahexaenoic acid (DHA), and the other received a <70% rTG (MEG-3) as 1,000 mg capsules containing 300 mg EPA and 200 mg DHA. Total intake was 2,750 and 2,500 mg EPA+DHA for the Ultimate Omega® and MEG-3 groups, respectively, with blood drawn at 4, 16 and 24 weeks and analyzed for serum and erythrocyte phospholipid fatty acid (PLFA) content. Results For erythrocyte PLFA profiles, EPA, docosapentaenoic acid (DPA) and DHA percentage of total erythrocyte PLFA were significantly greater for the Ultimate Omega® group than for the MEG-3 group, at week 16 (P < 0.05), as were the EPA:arachidonic acid (AA) ratio, DHA:AA ratio and EPA+DHA:AA ratio. For serum PLFA profiles, increases in EPA:AA ratio and EPA+DHA:AA ratio were significantly greater at week 4 in the Ultimate Omega® group compared to the MEG-3 group (P < 0.05). Conclusions These data suggest that the percentage of rTG in rTG fish oil preparations may evolve as a new chemoprofile/quality control marker that can influence its lipidomic pharmacodynamics. Additional investigations to assess the physiologic/vascular and metabolic/inflammasome responses to concentrated fish oil preparations differing in the percentage of rTG are warranted.