Medium-Chain Triglycerides (MCTs): Why Saturated Fat Isn't (Necessarily) the Enemy

Medium-chain triglycerides (MCTs) are a distinct class of "healthy" saturated fats that contain fatty acids with 6 to 12 carbon atoms. Unlike saturated long-chain triglycerides (LCTs) that are digested primarily through the lymphatic system, MCTs are mainly digested directly through the hepatic portal system. Thus, the medium-chain fatty acids found in MCT oil (powder) are quickly transported to the liver for metabolism and energy production.

MCTs also serve as immediate precursors to ketone bodies, an alternative fuel source for the gut, brain, muscles, and other body tissues/organs. Multiple clinical studies demonstrate the promising health benefits of MCT oil, specifically when replacing LCTs in the diet [1].

So, where do medium-chain triglycerides (MCTs) come from? Is coconut oil the same as MCT oil? Are MCTs good fats for keto (and other diets)? This article details the nature of MCT oil/powder and why MCTs are considered "healthy" fats.

What Are MCTs?

Triglycerides are fat molecules containing a glycerol backbone bonded to three fatty acids of varying chain lengths. MCTs are fat molecules that contain medium-chain fatty acids (MCFAs) exclusively.

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, people may refer to it as C6; caprylic acid is C8; capric acid is C10; lauric acid is C12. As a side note, odd-numbered saturated fatty acids like heptanoic acid (C7) occur in nature, but they are rarely found in food.

While saturated fat is a nutritional necessity, not all dietary fat is made equal. Most of the saturated fat in the modern western diet comes from long-chain triglycerides (LCTs) commonly found in deep-fried foods, red meat, soybean oil, and shortening. "Long-chain" in this context means that each saturated fatty acid in these triglycerides contains numerous carbon atoms (12 < n < 20).

Consuming a large amount of LCTs is a putative risk factor for several health conditions, specifically cardiovascular disease, type-2 diabetes/insulin resistance, and metabolic syndrome [2]. The unsaturated long-chain fatty acids in soybean oil and other vegetable oils may also undergo processing (partial hydrogenation) to create artificial trans fats that are well-known to clog arteries [3].

How Does MCT Oil Work: Research and Science

Saturated long-chain fatty acids are typically packaged into chylomicrons along with cholesterol and transported through the lymphatic system before being converted to chemical energy (or stored in body fat). The convoluted digestion of saturated long-chain triglycerides is not ideal for exercise performance and promoting weight loss, nor health and longevity [4].

On the other hand, the shorter hydrocarbon chain of medium-chain fatty acids allows them to absorb via the hepatic portal system and readily oxidize ("burn") for energy [5]. In turn, MCT oil provides a sustained fuel source for your brain, muscles, and other tissues/organs.

And as noted earlier, MCTs are a direct precursor for ketone body synthesis and are therefore an auxiliary energy source when carbohydrate intake is limited.

Five MCT Oil Benefits (Not Just for a Ketogenic Diet!)

Medium-chain triglycerides are "good" fats for any diet type, ketogenic or otherwise. But if you're interested in MCT oil, odds are you're also intrigued by the keto diet.

A keto diet is a high-fat, very-low-carb diet that significantly increases ketone body/ketone production. When a sufficiently large amount of ketones are circulating in the blood, you enter a state of "nutritional ketosis." 

Ketones are an alternative energy source for your brain and body [6]. We have a separate blog that goes more in-depth on the keto diet and weight loss.

Even if you're not on a keto diet, consuming more MCTs in place of LCTs is prudent.

Fatty Acids from MCTs May Increase Metabolic Rate

Several studies demonstrate that a high-fat diet (>50% total calorie intake) increases mitochondrial uncoupling protein (UCP) activity [7, 8]. UCPs are a class of cellular proteins in mitochondria that help dissipate membrane proton gradients, which causes energy to be lost as heat is generated. Therefore, UCPs are a direct mediator of thermogenesis.  

That might sound like a bunch of scientific mumbo jumbo, so here's an analogy to make it easier: UCPs are like natural gasoline for your "metabolic furnace." Just like adding gas to a fire makes it burn more intensely, UCPs help you burn more calories.

Research shows that free fatty acids, particularly medium-chain varieties, activate UCPs, particularly UCP1, in brown adipose tissue [9]. There is also preliminary evidence that MCTs increase the number of mitochondria in cells (a process known as mitochondrial biogenesis) [10].

The salient takeaway from all of the above is MCTs can increase your energy expenditure and facilitate weight loss.

MCTs Enhance Cognitive Function

Most fats don't cross the blood-brain barrier readily, but medium-chain fatty acids and ketones do [11]. Several clinical trials have shown that adding MCT oil to the diet can improve cognitive function and reduce the risk of neurodegenerative disease [12, 13]. In this regard, MCTs are like food for your brain, especially when carbohydrate intake is low. 

MCTs Help Lower Cholesterol and Blood Sugar

Contrary to long-chain fats (LCTs), MCTs have anti-coagulation properties and have been shown to reduce low-density lipoprotein (LDL) cholesterol and total cholesterol levels [14]. In so doing, MCTs can help "unclog" arteries and improve blood flow (which may lower the risk of heart disease, stroke, and fatty liver disease). 

Moreover, MCTs have metabolic and cardiovascular benefits by slightly reducing blood sugar levels, which is favorable for managing type-2 diabetes and insulin resistance [15].

MCTs Support Weight Loss by Reducing Food/Energy Intake

A recent meta-analysis suggests that MCTs reduce food intake, which is a welcome benefit if your main goal is weight loss [16]. In addition to MCTs being a dense source of energy, the ketones they help your body produce also help suppress appetite by increasing the production of a hormone called cholecystokinin (CCK) [17]. However, it remains unclear if MCTs affect appetite or satiety hormones directly.

MCTs Provide a Lasting Energy Boost

The neat thing about MCTs is that they go to work quickly, similar to sugar, but they won't cause you to crash or experience acute blood sugar swings like simple carbohydrates often do. As such, it may benefit athletes and gym-goers to use MCT oil as a dietary supplement before exercise/competition.

Coconut Oil vs. MCT Oil

Coconut oil is naturally rich in lauric acid, a medium-chain fatty acid with 12 carbons in its chemical structure. Coconut oil also contains modest amounts of capric acid (6 carbons), caprylic acid (8 carbons), and caproic acid (10 carbons). Naturally, most MCT oils are made by refining coconut oil and palm kernel oil.

However, consuming coconut oil is not the same as consuming MCT oil. High-quality MCT oil is typically enriched with caprylic acid (C8) and caproic acid (C10) as these specific medium-chain fatty acids are easier to digest and appear to have the most promise as "functional lipids" [18].

Key Takeaway: MCTs Are "Good" Fats (in Moderation, of Course)

Remember, not all saturated fat is as "bad" as some people assume. Depending on where the saturated fat comes from, it can be quite healthful. Think of MCTs as a source of "fast-acting, long-lasting energy." And unlike the "bad" saturated fats associated with weight gain, insulin resistance, and heart disease, MCTs appear to have numerous health benefits for just about everyone.

Be wary, though, as companies will cut corners by selling MCT oil and MCT oil powder supplements made from low-grade coconut oil and palm kernel oil. These products contain mostly lauric acid and relatively low amounts of "true" medium-chain fatty acids.