Benefits of Medium-Chain Triglycerides (MCTs)

What are MCTs?

Medium-chain triglycerides (MCTs) are types of fat which have shown to provide benefits to health and performance^{[1, 2]}. Triglycerides are the main constituents of fats, and each triglyceride is made up of three fatty acids with a backbone of glycerol. The majority of fats found in our food are long-chain triglycerides (LCTs). MCTs are triglycerides in which the fatty acids in their structure are 6 to 12 carbon atoms in length.

There are four main fatty acids that make up MCTs – known as medium-chain fatty acids (MCFAs) – and the number denotes their chain length:

• C6:0 Caproic acid
• C8:0 Caprylic acid
• C10:0 Capric acid
• C12:0 Lauric acid

Lauric acid is an interesting fatty acid in part because some information sources dispute it as an MCFA^[1]. However, because of the significant difference in its properties relative to longer-chain fatty acids, it fits better classed as an MCFA, in particular because nearly half of it is absorbed in the same way as other MCTs; also the mitochondrial metabolism of lauric acid doesn't rely on the carnitine-shuttle process as is the case with long-chain fatty acids (LCFAs).

MCTs are actually types of saturated fat; therefore they contribute to the saturated fat content of a food as labeled, despite not being treated like other saturated fats in the body. As there is an unduly negative perception of saturated fats, a high level of saturates on a food label may give a bad impression of the food even though a significant contribution to the figure is due to the MCT level.

As MCTs are saturated fats, they are not oxidized. Oxidation of fats is an issue because it is part of the disease process of cardiovascular disease and some cancers. MCTs are therefore not atherosclerotic (plaque-forming) like many other fats and are very heat- and light-stable.

Digestion, absorption, and metabolism of MCTs

As well as being structurally different from LCTs, MCTs are absorbed and metabolized in a different way and are treated more like an energy-dense carbohydrate source than a fat. Indeed, they are slightly less energy-dense than LCTs in that they provide approximately 8.3 kcal per gram compared to 9.0 kcal per gram.

After digestion, MCTs are absorbed differently to other fats in that they passively cross the small intestine wall. LCTs, on the other hand, are absorbed into the lymphatic system. Also, MCTs do not require bile salts for digestion, so humans find MCTs easier to digest and metabolize. The rate at which MCTs are absorbed is similar to that of glucose and faster than that of LCTs^[2].

Uses of MCTs

As you can see, MCTs are a very efficient and energy-dense nutrient, properties which allow MCTs to have numerous applications in clinical nutrition, sports nutrition and for general good health. MCTs are used as a source of fat in semi-elemental feeds for patients who have digestive issues or problems breaking down the more structurally complicated nutrients that we find in regular diets. MCTs are also better tolerated in those diagnosed with inflammatory bowel disorders like Crohn’s and colitis^[3] and post gallbladder removal^[4].

Athletes, especially long-distance runners and cyclists, often prefer to supplement with MCTs, including them as a significant contribution to calorie intake, especially in the run-up to an event. Often these athletes may even prioritize their intake of MCTs over additional carbs, as MCTs provide an equally efficient source of energy, but in a more concentrated form; i.e. you need less for a similar amount of energy (carbs provide 4 kcal per gram).

As MCFAs are metabolized differently to LCFAs, high levels of MCFAs do not produce energy through the typical metabolic processes following food intake. Instead, MCFAs – with the exception of lauric acid – are more likely to be used for ketogenesis^[1]. Ketogenesis is a metabolic state where ketone bodies are produced and is a survival mechanism where the brain and heart muscle use ketone bodies in order to keep functioning. Ketogenic diets – although controversial – are a popular dietary strategy for weight loss, and have been shown to be beneficial in epilepsy and other neurological conditions^{[5, 6]}. A typical ketogenic diet sees an individual consuming a very low carb intake, a fairly low protein intake and a high fat intake with the goal of leading the body into a ketotic state. However, MCFAs do not require the same physiological conditions for ketogenesis, which can occur even in the presence of a higher carbohydrate intake, so they are particularly useful for those wanting to follow a ketogenic diet.

MCTs in foods

MCTs are not that common in foods, but are found in small amounts in dairy fats like butter (about 8.3g per 100g) and some types of cheese (for example, Cheddar cheese is typically 1.9g per 100g), but the richest sources are coconut oil (about 58.7g per 100g) and palm kernel oil (about 54.2g per 100g).

MCTs in Huel

The MCTs used in Huel are derived from coconut oil and, after being extracted from coconut oil, they are spray-dried onto a carrier and the resulting powder is blended with the other Huel ingredients.

The total MCT content in Huel (US v1.1) is approximately 1.1g per 100g and provides over 2.5% of the total energy of Huel. Roughly 45% of the saturated fat content of Huel, therefore, comes from MCTs. Of the MCFAs in Huel, over 35% are capric acid, over 59% are caprylic acid, around 2% are caproic acid and around 4% are lauric acid.

References

1. Examine.com. Medium-chain triglycerides. Date Accessed: 04/04/19. [Available from: https://examine.com/supplements/mcts/]
2. Dean W and English J. nutritionreview.org. Medium Chain Trigylcerides (MCTs). Date Accessed: 09/04/19. [Available from: https://nutritionreview.org/2013/04/medium-chain-triglycerides-mcts/]
3. Hunter J. crohns.org.uk. Which dietary treatment should I choose? Date Accessed: 04/09/19 crohns.org.uk [Available from: http://www.crohns.org.uk/crohns_disease/nutritional_therapy/which-dietary-treatment-should-i-choose].
4. Ladas SD, et al. Comparison of the effects of medium and long chain triglyceride containing liquid meals on gall bladder and small intestinal function in normal man. Gut. 1984; 25(4):405-11.
5. Liu YM, et al. Medium-chain triglyceride ketogenic diet, an effective treatment for drug-resistant epilepsy and a comparison with other ketogenic diets. Biomedical journal. 2013; 36(1):9-15.
6. Neal EG, et al. A randomized trial of classical and medium-chain triglyceride ketogenic diets in the treatment of childhood epilepsy. Epilepsia. 2009; 50(5):1109-17.