Incorporation of dietary n-3 fatty acids into selective phosphatidylcholine lipids in human plasma after salmon intake

Authors: ZACEK, PETR - Us Forest Service (FS); Bukowski, Michael; Raatz, Susan; Picklo, Matthew

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2016
Publication Date: 4/1/2017
Citation: Zacek, P., Bukowski, M.R., Raatz, S.K., Picklo, M.J. 2017. Incorporation of dietary n-3 fatty acids into selective phosphatidylcholine lipids in human plasma after salmon intake. Journal of Federation of American Societies for Experimental Biology. 31:42.4.

Interpretive Summary:

Technical Abstract: Elevated intake of n-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) is associated with reduced risk for cardiovascular disease. Intake of n-3 LCPUFA is often quantified by analysis of plasma phospholipid fatty acids (PLFA); however, the typical analysis by gas chromatography does not allow for determination of the phospholipid species that are enriched by the n-3 LCPUFA. In this work, we tested the hypothesis that the n-3 LCPUFA, namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are incorporated into select phosphatidylcholine (PC) species following intake of farm-raised, Atlantic salmon. Plasma samples were obtained from a randomized, cross-over designed study in which participants (n = 9) consumed farm-raised Atlantic salmon at levels of 90 g and 180 g twice weekly for 4 weeks with an 8 week washout between treatments. Plasma lipids were extracted and analyzed using a shotgun MS/MS method with the capability to quantify isobaric PC species. Our data indicate that under basal conditions, EPA and DHA are incorporated into PC species containing palmitic acid (PA), stearic acid (SA), and oleic acid (OA) as the complementary fatty acid in the concentration order of PA>SA>OA. EPA content was enriched in PA, SA, and OA species following salmon intake whereas only PA and SA containing DHA species were elevated following intake. Interestingly, PCs containing docosapentaenoic acid (DPA) were not elevated even though the salmon contained DPA. PC species containing n-6 PUFA demonstrated a similar pattern of PA>SA>OA as the complementary fatty acids. No changes in n-6 containing PC species occurred following salmon intake. Although linoleic acid (LA) was highly enriched in total PC, LA was not detected as a complementary fatty acid to any n-3 LCPUFA species and was a minority complementary species for other n-6 PUFA. In conclusion, our data demonstrate that (1) n-3 LCPUFA incorporate into selective PC pools some of which increase with dietary n-3 LCPUFA intake, and (2) there exists a hierarchy of PUFA containing PC species with selectivity for lower carbon length and higher saturation level for the complementary fatty acid. These data allow for a more refined characterization of biomarkers for PUFA intake and understanding of PC biochemistry in humans.