2018 Volume 18 Issue 8 Pages 375-381
The medium-chain triglycerides (MCTs) are composed of medium-chain fatty acids and glycerol. The MCTs are easily and quickly digested to free fatty acids in the small intestine and subsequent quickly metabolized as energy sources compared with long-chain triglycerides. This is because that the micellization with the bile is not necessary for the digestion and absorption of MCTs, the medium-chain fatty acids digested in the small intestine are not re-synthesized into triglycerides and carnitine binding to the fatty acids, a rate-controlling step of β-oxidation, is not necessary. In addition, several studies demonstrated that intake of MCTs in animals enhanced expression and/or enzyme activity of genes related to metabolism such as β-oxidation, glycolysis system, citric acid cycle, electron transport system and fatty acid synthesis. The intake of MCTs enhanced the insulin action in animal models with insulin resistance or with undernutrition. These results indicate that MCTs has functions of activating energy metabolism proactively by enhancing expression/activity of the rate-controlling enzymes as well as of an energy sources. Furthermore, recent studies have demonstrated that MCT metabolizes such as β-hydroxybutyric acid and citric acid can enhance an epigenetic memory histone acetylation. We have demonstrated that a medium-chain fatty acid caprylic acid enhanced not only expression of intestinal genes related to digestion/absorption of lipids and carbohydrates, but also that of their transcriptional factor peroxisome proliferator-activated receptor α and the histone acetyl-transferase CREB binding protein/p300. These evidences indicate that MCTs can enhance metabolism and digestion/absorption of the nutrients by enhancing expression of genes related to metabolic genes and those related to enhancing the histone acetylation.
