MCT fats for long-chain fatty acid oxidation disorders

Beta-Oxidation is the process where the body breaks down fatty acids into energy. This fat can come from food or from the breakdown of the body’s own fat stores. The fatty acids first enters the cell through the cells membrane to be channelled straight to the power house of the interior of the cells: the mitochondria. Here, the fatty acids are broken down into shorter chains and energy is produced in the process. These steps are controlled by individual enzymes that specialise in only 1 step each. There are enzymes for the transport into the cell and there are enzymes to break down the fatty acids. There are even specific enzymes for the different length fatty acid chains. Fatty acids are categorised as short-chain, medium-chain and long-chain fatty acids. When a long-chain fatty acid is channeled into the mitochondria by transporter enzymes, then the enzyme responsible for long-chain fatty acids will be active first. Other enzymes can only become active when the fatty acid has been shortened to the correct length.

The aim of dietary treatment is to minimize fatty acid oxidation by avoiding fasting and providing adequate non fat energy during stress. In patients with VLCAD, LCHAD deficiency and TFP defects, MCT provides a useful energy source and may have other beneficial effects. The quantity of MCT should be determined by a clinician or a dietitian only and is dependent on the age, bodyweight and medical condition of the patient.

MCT fats are medium-chain fatty acids. These fatty acids can be used as an energy source by people with a disorder in the breakdown of long-chain fatty acids. It is a different enzyme that facilitates the breakdown of the medium-chain fatty acids to create energy. For this reason, MCT fats are specifically used in the therapy of disorders in the oxidation of long-chain fatty acids. MCT fats are an energy source which can be metabolised easily, especially in muscle cells. MCT fat can be taken before physical strain to provide the hard-working muscle cells with sufficient energy. In rest periods, e.g. during the night, MCT fats are not normally needed. In the daily diet, MCT fat counterbalances the calorie deficit from low-fat foods. The respective quantity is determined individually by the dietary team. It is important to note that, MCT fat should be used as to meet and not exceed energy requirements, as too much MCT fat is stored as body fat. When stored as body fat, the excess MCT fat is converted into long-chain fatty acids therefore no longer available as an energy source.