Sn1,3 Regiospecificity of DHA (22:6ω-3) of Plant Origin (DHA-Canola^®) Facilitates Its Preferential Tissue Incorporation in Rats Compared to sn2 DHA in Algal Oil at Low Dietary Inclusion Levels

Background/Objectives: Regiospecificity in triacylglycerols (TAGs) influences absorption/bioavailability of dietary fatty acids. We evaluated whether sn1,3 located DHA (22:6ω3) of a transgenic higher plant (DHA-Canola^®) preferentially facilitates its tissue incorporation as compared to sn2 positioned DHA (DHASCO^® of algal origin). Methods: Sprague Dawley rats were fed diets (12 weeks) containing DHA-Canola or DHA-Control (a blend of DHASCO^® and high oleic sunflower seed oil (HOSO)) at 0.3%, 1%, 3%, and 6% (w/w), or 7% HOSO prior to determination of tissue fatty acids. Results: At 0.3 and 1% w/w supplementation, plasma, liver and cardiac tissue DHA incorporation was higher in the plant-based oil (DHA-Canola vs. DHA-Control; p < 0.05), whilst sn2 enriched algal oil yielded better outcomes at higher doses (at 3% inclusion, plasma values were 7.8 vs. 5.9%, and at 6% supplementation, 10.0 vs. 7.9 in favor of DHA-Control, p < 0.05) At lower intakes, sn1,3 regiospecificity (DHA-Canola) increased the omega-3 index, a clinically relevant biomarker, compared to DHA-Control (p < 0.05). Similarly, a build-up of 20:5ω3 and 22:5ω3 occurred with DHA-Canola. Consequently, total omega3s were higher in this latter group. Conclusions: At lower intakes, sn1,3 regiospecificity of DHA leads to its preferential tissue incorporation compared to sn2 DHA.