Saturated fat enhances incorporation of n-3 polyunsaturated fatty acids into plasma and erythrocyte lipids in healthy humans

Background/Aims: High fat meals have been previously shown to promote bioavailability of n-3 polyunsaturated fatty acids (n-3PUFA). While the effect of dietary fat types on incorporation of n-3PUFA into blood and tissue lipids has been widely discussed in the literature, this phenomenon has not been reported in humans to-date.
Methods: This was a randomised, controlled, parallel, dietary intervention trial involving 25 healthy adults aged 18 to 65 years. Subjects consumed foods rich in either saturated (SFA) or n-6 polyunsaturated fatty acids (n-6PUFA), all supplemented with 2.4g n-3PUFA daily for 6 weeks. Blood samples were collected after an overnight fast, at baseline and post-intervention, for analysis of plasma and red blood cell fatty acids.
Results: Linoleic acid increased significantly in plasma but not erythrocytes following the n-6PUFA diet, and did not change after the SFA diet. There was an increase in eicosapentaenoic acid (EPA) which was significantly higher (2 fold) after the SFA compared to the n-6PUFA diet. There was also a greater increase in docosahexaenoic acid (DHA) after the SFA diet, although this was not significantly different to the n-6PUFA diet. Conversely there was a significant reduction in plasma docosapentaenoic acid (DPA) which was 2 fold greater following the n-6PUFA compared to the SFA diet.
Conclusions: Dietary background fat type affects n-3PUFA incorporation into plasma and erythrocytes in healthy subjects. Dietary SFA facilitate n-3PUFA incorporation into plasma and erythrocytes compared to dietary n-6PUFA.
Funding source(s): Hunter Medical Research Institute (HMRI) and Coordenação Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil).