Medium-Chain Triglycerides (MCTs)

Whether you’re inveterate keto dieter or new to the carb-less lifestyle, chances are you’ve heard a good amount about medium-chain triglycerides (MCTs). But what is it about MCTs that makes them so popular on the ketogenic diet? What are the benefits of MCTs and how do they impact ketosis?

This article will get you up to speed on MCTs and help you decide which types are best for your keto lifestyle.

How Do MCTs Work on the Keto Diet?

If you’re not familiar with the ketogenic diet, it’s essentially a very-low-carb diet that encourages a higher intake of healthy fats and quality protein. For most people, being on the keto diet means consuming 30 grams or less of carbohydrates per day, most of which come indirectly from foods like vegetables, dairy, and nuts/seeds.

Normally, glucose (sugar) serves as the body’s go-to energy source. By restricting your carb intake to such a sharp degree, the body no longer has its “usual” source of fuel, so it begins to metabolize more of the fat that you eat, as well as your body fat, for energy.

In this regard, carbohydrates/sugars are not essential in the human diet since the body can create glucose endogenously from other nutrients (i.e. fats and proteins). This is why fat and protein are essential in the human diet, and you shouldn’t be fearful that the keto diet is unhealthy or dangerous; in fact, it’s quite the opposite!

As a result of the increase in fat metabolism on the keto diet, organic molecules called ketones are produced in the liver (hence the term “ketogenic” is used to describe this diet). Ketones serve as an alternative energy source for many organs and tissues throughout the body, even skeletal muscle and the brain.

After following the keto diet for several days, the amount of ketones in your body will accumulate to a point where you enter ketosis. Once you establish and maintain ketosis, a variety of metabolic/physiological adaptations occur which have been shown to reduce the risk of a multitude of chronic health conditions, including¹:

• Type-2 diabetes
• Metabolic syndrome
• Cardiovascular disease
• Dementia
• Parkinson’s disease
• Alzheimer’s disease

Sounds pretty awesome, right? But where do MCTs come into play on the keto diet and how do they impact ketosis?

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What Are Medium-Chain Triglycerides (MCTs)?

MCTs is the acronym for a unique subclass of saturated dietary fats that contain 6, 8, 10, or 12 carbons in their fatty acid chemical structure. Most of the saturated fat found in a typical Western diet is in the form of long-chain triglycerides (LCTs) which are packaged into micelles in the small intestine and absorbed through the lymphatic system.

Eating excessive amounts of saturated LCTs is well-known to increase the risk of cardiovascular conditions, such as atherosclerosis, hyperlipidemia, hypertension, stroke, and much more.²

MCTs, on the other hand, are not transported through the lymphatic system like saturated LCTs. Rather, MCTs are like a form of “quick-absorbing” fat since they are broken down into medium-chain fatty acids (MCFAs) in the small intestine and taken up by the hepatic portal system.³ In turn, MCFAs are rapidly oxidized in the liver, meaning they help provide energy (ATP) to the body while creating more ketones in the process.

It may help to think of MCTs as being an easy-to-digest, lasting source of energy that won’t leave you with crazy blood sugar swings like sugars often do. This is why many athletes are turning to things like MCT oil and MCT powder to help fuel their training and competitions rather than the conventional “carb up” meal approach that has been used for decades.

But before you jump on the MCT bandwagon, it’s important to note that not all MCTs are created equal...

Different Types of MCTs

MCTs are molecules that contain glycerol bonded to various medium-chain fatty acids (MCFAs). There are four saturated MCFAs, each with a specific number of carbons in its chemical structure, including:

• Caproic acid - 6 carbons
• Caprylic acid - 8 carbons
• Capric acid - 10 carbons
• Lauric acid - 12 carbons

Since caproic acid has six carbons in its chemical structure, it is sometimes referred to as C6; caprylic acid is C8; capric acid is C10; lauric acid is C12.

The main distinction is that lauric acid, which is mainly found in coconut, doesn’t appear to have the same benefits as the other three MCFAs. In fact, scientists argue that lauric acid shouldn’t qualify as a MCFA but rather a long-chain fatty acid.⁴

Caprylic acid and capric acid, on the contrary, are suggested to be the best MCFAs since they have been shown to increase ketone body production to a greater degree than lauric acid without the associated gastrointestinal distress that caproic acid often causes.⁵

When you’re looking for a high-quality MCT oil or MCT powder, make sure to read the label and verify what the actual composition of the fatty acid profile is. You can find supplements that contain MCTs with purely C8 and C10 fatty acids, which should be ideal for those on the ketogenic diet. Pure C8 and C10 MCTs are produced by filtering natural MCT sources, particularly palm kernel oil and coconut oil.

However, if you’re simply consuming coconut oil, you’re getting a greater amount of lauric acid as opposed to capric and caprylic acids. Make no mistake that lauric acid has some benefits, particularly when used topically for skin and hair health, but the jury is still out on whether it operates like a true MCFA when eaten.⁶

Moreover, research has shown that even in the presence of high blood glucose, caprylic acid is readily absorbed from the gastrointestinal tract and rapidly oxidized.⁷ In other words, the body prefers to use MCTs, especially C8, over glucose for energy even if you’re not on the keto diet. Thus, active individuals who consume higher-carb diets can benefit from using MCTs.

Benefits of MCTs on Keto

In many ways, MCTs are the optimal energy source for your body since they go to work immediately and provide long-lasting benefits. Contrast that with sugar and starchy carbs, which typically provide a short burst of energy followed by a crash that leaves you feeling lethargic and mentally foggy.

In addition to the energy that MCTs provide, these unique saturated fats have a myriad of other health benefits backed by scientific and clinical research, including:

• Improving cognitive function and mental performance⁸
• Enhancing fat burning and increasing metabolic rate⁹
• Reducing LDL (“bad”) cholesterol and promoting healthy blood sugar balance¹⁰
• Decreasing inflammation and oxidative stress¹¹
• Boosting athletic performance¹²

It’s important to note that many of these benefits stem from the fact that MCTs help your body produce more ketones as part of the keto diet. In other words, MCTs are arguably the best fat source for helping you get into ketosis and ensuring that you stay on top of your game throughout the day.

References

1. Veech, R. L. (2004). The therapeutic implications of ketone bodies: the effects of ketone bodies in pathological conditions: ketosis, ketogenic diet, redox states, insulin resistance, and mitochondrial metabolism. Prostaglandins, leukotrienes and essential fatty acids, 70(3), 309-319
2. De Lorgeril, M., & Salen, P. (2012). New insights into the health effects of dietary saturated and omega-6 and omega-3 polyunsaturated fatty acids. BMC medicine, 10(1), 50.
3. Bach, A.C., and Babayan, V.K. Medium-chain triglycerides: An update. Am J Clin Nutr, 1982, 36: 950-962.
4. McGarry, J. D., & Foster, D. W. (1971). The Regulation of Ketogenesis from Octanoic Acid. Journal of Biological Chemistry, 246(4), 1149-1159.
5. Schwabe, A. D., Bennett, L. R., & Bowman, L. P. (1964). Octanoic acid absorption and oxidation in humans. Journal of applied physiology, 19(2), 335-337.
6. Enig, M. G. (1996, April). Health and nutritional benefits from coconut oil: an important functional food for the 21st century. In AVOC Lauric Oils Symposium, Ho Chi Min City, Vietnam(Vol. 25).
7. Miles, J. M., Haymond, M. W., Nissen, S. L., & Gerich, J. E. (1983). Effects of free fatty acid availability, glucagon excess, and insulin deficiency on ketone body production in postabsorptive man. Journal of Clinical Investigation, 71(6), 1554.
8. Augustin, K., Khabbush, A., Williams, S., Eaton, S. J., Orford, M., Cross, H., ... & Williams, R. (2018). Mechanisms of action for the medium-chain triglyceride ketogenic diet in neurological and metabolic disorders. The Lancet Neurology, 17(1), 84-93.
9. Stewart, J.W., Wiggers, K.D., Jacobsen, N.L., Berger, P.J. Effect of various triglycerides on blood and tissue cholesterol of calves, J Nutr, 1978, 108: 561-566.
10. Sullivan, P. G., Rippy, N. A., Dorenbos, K., Concepcion, R. C., Agarwal, A. K., & Rho, J. M. (2004). The ketogenic diet increases mitochondrial uncoupling protein levels and activity. Annals of neurology, 55(4), 576-580.
11. Geng, S., Zhu, W., Xie, C., Li, X., Wu, J., Liang, Z., ... & Wu, R. (2016). Medium-chain triglyceride ameliorates insulin resistance and inflammation in high fat diet-induced obese mice. European journal of nutrition, 55(3), 931-940.
12. Nosaka, N., Suzuki, Y., Nagatoishi, A., Kasai, M., Wu, J., & Taguchi, M. (2009). Effect of ingestion of medium-chain triacylglycerols on moderate-and high-intensity exercise in recreational athletes. Journal of nutritional science and vitaminology, 55(2), 120-125.

Article By: Elliot Reimers

Elliot received his B.S. in Biochemistry from the University of Minnesota and is currently working on his M.S.in Pharmacology & Toxicology at Michigan State University. He has been a freelance science writer for over six years, with an emphasis in nutritional biochemistry, exercise physiology, and pharmacology. As such, he is thoroughly passionate about helping others comprehend scientific research and understand the biochemical mechanisms that underpin human health, performance, and longevity; he hopes that such knowledge will help people make smarter decisions about what they put in their body. In his free time, you can most likely find him hoisting barbells, hiking the mountains of Colorado, or working on his supplement science website - www.supplementuniversity.com.