Molecular species-specific differences in composition of triacylglycerols of mouse adipose tissue and diet.

It has been demonstrated that the composition of molecular species of triacylglycerol (TG) in adipose tissue broadly reflects dietary TG molecular species composition. Medium-chain fatty acids (FAs) are not accumulated easily relative to long-chain FAs in body fat. The objective of the present study was to examine whether medium-chain FAs were incorporated into body fats. To this end, the composition of TG molecular species stored in the epididymal adipose tissues of mice fed a coconut oil diet was analyzed by gas chromatography. Most TG molecular species detected in mice adipose tissues contained long-chain fatty acyl moieties, even though dietary coconut oil is rich in TG molecular species composed of medium-chain fatty acyl moieties. The major medium-chain FAs in the dietary oil, decanoic, and lauric acids were seen in TG molecular species having 1 or 2 long-chain acyl moieties, such as palmitoyl and oleoyl. These results suggest that molecular species composition of TG in mice adipose tissue is affected by coconut oil. In summary, our findings demonstrate that the metabolic processes for TG molecular species with long- and/or medium-chain FAs in TG synthesis and storage differ in the intestinal lumen and adipose tissue.