No abstract

Summary Previous studies have demonstrated that fatty acid oxidation in the liver may affect food intake. This study examined the influence of preloading of medium-chain triacylglycerol (MCT) on food intake in comparison with long-chain triacylglycerol (LCT). Male rats were fasted for 18 h and then administered LCT or MCT emulsion orally. Each group of rats was allowed to rest for 30 min, and then food intake during 1 h was measured. Food intake in the MCT group was significantly lower than that in the LCT group. To examine the influence of hepatic oxidation, the MCT ϩ MA group was injected intraperitoneally with mercaptoacetate (MA), an inhibitor of fatty acid oxidation, 2 h before ingestion of MCT emulsion. Then, 30 min after ingestion of LCT or MCT emulsion, food intake was measured for 1 h. Food intake in the MCT group was significantly lower than that in the LCT group, but there was no significant difference between the MCT ϩ MA group and the LCT group. Food intake in the MCT ϩ MA group was significantly higher than that in the MCT group. The hepatic ATP content after MCT ingestion was significantly higher than that after LCT ingestion, but there was no significant difference between the MCT ϩ MA group and the LCT group. The hepatic ATP content after MCT ϩ MA ingestion was significantly lower than that after MCT ingestion. These results suggest that ingestion of medium-chain fatty acid (MCFA) increases the liver ATP content in fasted rats, consequently decreasing food intake.

This study compared the serum lipid concentrations after a single dose of medium-chain triglycerides (MCT) or long-chain triglycerides (LCT) between individuals grouped according to the body mass index (BMI). Twenty-five males participated as volunteers, the test diet containing 10 g of MCT or LCT. Blood samples were collected up to 6 h after the intake of a test diets. The LCT diet resulted in significantly greater increases in areas under the curves (AUCs) for serum and chylomicron triglyceride in the BMI > or = 23 kg/m2 group than those in the BMI < 23 kg/m2 group. The magnitude of response after intake of the MCT diet by the BMI > or = 23 kg/m2 group was significantly lower than that after the LCT diet. These results suggest that, in subjects with BMI > or = 23 kg/m2, the intake of MCT is preferable to that of LCT for maintaining postprandial triglyceride at a low concentration.

Summary Previous studies indicated that a medium-chain triacylglycerol (MCT) diet could inhibit body fat accumulation. It is also well established that exercise can reduce fat mass. However, the effects of a combination of MCT diet and exercise on reduction of fat mass have not been studied. Here we examined whether MCT diet and exercise intervention exert cooperative effects on body composition. Rats were assigned to 4 groups: 1. LCT diet, control (LCT-C); 2. MCT diet, control (MCT-C); 3. LCT diet, exercise (LCT-E); 4. MCT diet, exercise (MCT-E). After the 6-wk intervention, visceral fat mass was measured by CT scan and dissection, and energy expenditure was estimated for 24 h. The value of the visceral fat mass showed a significant correlation between CT scan and dissection ( r ϭ 0.995, p Ͻ 0.001). Visceral fat mass in the MCT-C group was lower than that in the LCT-C group. Furthermore, the fat-lowering effects were greater in the MCT-E group than that in either intervention alone. Thus significant effects of the MCT diet and exercise on the reduction of visceral fat mass were observed. Energy expenditure was significantly higher in the MCT-E group than in the other groups. Our present findings suggest that combined intervention of MCT diet and exercise has an additive effect on reduction of visceral and subcutaneous fat accumulation, and that this effect may be partially related to increased energy expenditure. However, future studies are necessary to define the relationship between energy expenditure and fat mass accumulation.

Lymphatic transport of a mixture of medium-chain TAG (MCT) and long-chain TAG (LCT) was studied in lymph-cannulated rats. Animals were administered a test emulsion containing either triolein, tricaprylin, or a 1:1 mixture of triolein and tricaprylin, and the lymph was collected for 24 h. The lymphatic recovery rate of medium-chain FA (MCFA) was significantly higher in rats given the TAG mixture than in those given MCT alone. The lymphatic recovery rate of long-chain FA (LCFA) also was significantly higher in rats given the TAG mixture than in those given LCT alone. No TAG containing three MCFA (i.e., MCT) was detected, and 37.7% of TAG containing one or two MCFA was detected in the lymph TAG when rats were given the TAG mixture. These results indicate that lymphatic transport of MCFA and LCFA can be modified by the combination of MCT and LCT.