Human breast milk fat contains 60-75% of palmitic acid (PA) at sn-2 position (Hsn-2 PA) of the triacylglycerols (TAG). This peculiar position of PA provides specific physiological properties to human milk fat. However, it is not clear by which mechanism Hsn-2 PA exerts its activities. One possibility may be reconducted to an increased PA incorporation into tissue phospholipids (PL), which may modify biosynthesis of fatty acid – derived bioactive lipids, such as endocannabinoids (EC) and their congeners.
To test our hypothesis, we fed rats for 5 weeks diets containing Hsn-2 PA or PA randomly distributed in TAG (Lsn-2 PA), with similar total PA concentration. Fatty acid profile, EC and congeners were measured in different tissues by LC-MS.
Rats on Hsn-2 PA diet had lower levels of the EC anandamide (AEA) with concomitant increase of its congener palmitoylethanolamide (PEA) and its precursor PA into visceral adipose tissue PLs. In addition, we found an increase of oleoylethanolamide (OEA) in liver, muscle and brain, associated to higher levels of its precursor oleic acid in liver and muscle. Changes in EC and congeners were associated to a decrease of circulating TNF alpha after LPS challenge, and to an improved feed efficiency.
Our data suggest that dietary Hsn-2 PA, by modifying EC and congeners biosynthesis in different tissues may concur in the physiological regulation of energy metabolism, brain function and body fat distribution.

Dietary high palmitic acid in sn-2 position of triacylglycerols may exert its physiological functions by modulating endocannabinoids and congeners biosynthesis