Fat is generally not as good choice of dietary fuel during intense exercise because it is more slowly absorbed and oxidised compared to carbohydrate. This decreases the usefulness of fatty acids as a fuel for energy during athletic performance. However, medium chain triglycerides are an exception because of the different way they are absorbed and metabolised in humans. This relates to their structure, which comprises predominately of fatty acids of between 6 and 12 carbons in length. Medium chain triglycerides are hydrolysed to medium chain fatty acids in the duodenum, and due to their increased solubility in water, this process requires lower concentrations of bile acids compared to longer chain fatty acids. Once hydrolysed from their glycerol backbone, the medium chain fatty acids enter the enterocytes of the gut. From here they pass into the portal vein bound to albumin and are subsequently oxidised in the liver as rapidly as glucose. It has been estimates that they enter circulation and are metabolised around 250 times faster than long chain triglycerides.
Medium chain triglycerides are made up of 1 to 2 % C6:0, 65 to 75 % C8:0, 25 to 35 % C10:0 and 1 to 2 % C12:0. They are synthesised by processing coconut oil through fractionation of the fatty acids, followed by esterification to glycerol. Medium chain triglycerides were first introduced to help with lipid absorption disorders, because the unique way they are absorbed is beneficial in some conditions. While some natural sources such a coconut can supply some medium chain triglycerides, supplements are necessary in order to benefit fully from their effects. One of the main advantages of medium chain triglycerides is the relatively soluble nature of their fatty acids in water. This not only relates to the smaller molecular size of the fatty acids, but also the fact that they are weak electrolytes and are highly charged at neutral pH. Medium chain triglycerides are rapidly oxidised to ketone bodies, and can be used medicinally for those requiring a quick source of energy for growth. For the same reason they are also useful to athletes as a quick source of energy.
