PUFAs acutely affect triacylglycerol-derived skeletal muscle fatty acid uptake and increase postprandial insulin sensitivity.

Background: Dietary fat quality may influence skeletal muscle lipid processing and fat accumulation, thereby modulating insulin sensitivity. Objective: The objective was to examine the acute effects of meals with various fatty acid (FA) compositions on skeletal muscle FA processing and postprandial insulin sensitivity in obese, insulin-resistant men. Design: In a single-blind, randomized, crossover study, 10 insulin-resistant men consumed 3 high-fat mixed meals (2.6 MJ), which were high in SFAs, MUFAs, or PUFAs. Fasting and postprandial skeletal muscle FA processing was examined by measuring differ-ences in arteriovenous concentrations across the forearm muscle. |:H2]Palmitate was infused intravenously to label endogenous tri-acylglycerol and FFAs in the circulation, and [U-13C]palmitate was added to the meal to label chylomicron-triacylglycerol. Skeletal muscle biopsy samples were taken to assess intramuscular lipid metabolism and gene expression. Results: Insulin and glucose responses (AUC) after the SFA meal were significantly higher than those after the PUFA meal (P = 0.006 and 0.033, respectively). Uptake of triacylglycerol-derived FAs was lower in the postprandial phase after the PUFA meal than after the other meals ( AUC_{60_24o}; P = 0.02). The fractional synthetic rate of the tri-acylglycerol, diacylglycerol, and phospholipid pool was higher after the MUFA meal than after the SFA meal. PUFA induced less transcrip-tional downregulation of oxidative pathways than did the other meals. Conclusion: PUFAs reduced triacylglycerol-derived skeletal muscle FA uptake, which was accompanied by higher postprandial insulin sensitivity, a more transcriptional oxidative phenotype. and altered intra-myocellular lipid partitioning and may therefore be protective against the development of insulin resistance. This trial was registered at clin-icaltrials.gov as NCT01466816. [ABSTRACT FROM AUTHOR]