Lymphatic recovery of exogenous oleic acid in rats on long chain or specific structured triacylglycerol diets

Specific structured triacylglycerols, MLM (M=medium-chain fatty acid, L=long-chain fatty acid), rapidly deliver energy and long-chain fatty acids to the body and are used for longer periods in human enteral feeding. In the present study rats were fed diets of 10 wt% MLM or LLL (L=oleic acid [18∶1n−9], M=caprylic acid [8∶0]) for 2 wk. Then lymph was collected 24 h following administration of a single bolus of ¹³C-labeled MLM or LLL. The total lymphatic recovery of exogenous 18∶1n−9 24 h after administration of a single bolus of MLM or LLL was similar in rats on the LLL diet (43% and 45%, respectively). However, the recovery of exogenous 18∶1n−9 was higher after a single bolus of MLM compared with a bolus of LLL in rats on the MLM diet (40% and 24%, respectively, P=0.009). The recovery of lymphatic 18∶1n−9 of the LLL bolus tended to depend on the diet triacylglycerol structure and composition (P=0.07). This study demonstrated that with a diet containing specific structured triacylglycerol, the lymphatic recovery of 18∶1n−9 after a single bolus of fat was dependent on the triacylglycerol structure of the bolus. This indicates that the lymphatic recovery of long-chain fatty acids from a single meal depends on the overall long-chain fatty acid composition of the habitual diet. This could have implications for enteral feeding for longer periods.