MCT oil is made up of medium-sized fat molecules (not short and not long). Hence the name, medium-chain triglycerides. A “triglyceride” is science-speak for a basic fat molecule. Triglycerides have two components: one glycerol molecule (often referred to as the ‘backbone’ of the triglyceride) and three fatty acids (that’s why “tri” is included in “triglyceride”). So, medium-chain triglyceride simply reflects the medium-sizes fatty acids used to make them. This figure should help:

medium-chain triglyceride

In this case, three identical fatty acids (lauric acid – C12) bind with glycerol to make an MCT. But not all three fatty acids need to be lauric acid to make an MCT. They can be any one of the medium-chain fatty acids (see below). So in a different MCT molecule, we might have two caprylic fatty acids and one capric fatty acid held together by a glycerol molecule.

Fatty Acids

Fatty acids are the building blocks of triglycerides in the same way that amino acids are the building blocks of proteins. For argument’s sake, there are four types of fatty acids used to make MCTs [*] (although some studies don’t include caproic acid-C6 [*] or lauric acid-C12 [*] in the definition of a medium-chain fatty acid):

  1. Caproic acid (C6)
  2. Caprylic acid (C8)
  3. Capric acid (C10)
  4. Lauric acid (C12)

Fatty acids are made up of mostly carbon and hydrogen atoms (they also contain a carboxylic acid group, but we won’t go there for now). The length of the carbon chain (or more simply the number of carbon atoms in a fatty acid) ranges from 4 – 30 carbons. But most have 12 – 24 carbon atoms in their chains.

Clearly then, the number of carbon atoms in the fatty acids used to make a triglyceride dictates how that triglyceride is classified [*][*][*]:

  • Short-chain triglycerides (SCT) contain 6 or fewer carbon atoms. One example of a fatty acid found in SCT is acetic acid (aka vinegar).
  • Medium-chain triglycerides (MCT) contain 7 – 12 carbon atoms. One example of a fatty acid found in MCT is caprylic acid.
  • Long-chain triglycerides (LCT) contain 13 – 21 carbon atoms. One example of a fatty acid found in LCT is oleic acid.
  • Very long-chain fatty acids (VLCFA) contain 22 or more carbon atoms. Fatty acids with chains containing 26 or more carbons are called ultra long-chain fatty acids.

MCTs are usually derived from coconut oil since approximately 50% of the fat in coconut oil is MCTs [*]. But MCTs are also found at lower concentrations in other foods, like grass-fed butter, palm oil, and full-fat yogurt. That’s why coconut oil is such a powerhouse; it contains a very high proportion of MCTs (which seem to be the “active ingredient”).

Digesting Triglycerides

The number of carbon atoms in triglycerides (i.e., fats) ultimately affects how the body processes them. As a rule of thumb, the longer the fatty acid chain, the harder it is for the body to use it for energy (but the more energy they pack). That’s because it takes longer to break down and extract the chemical energy to make adenosine triphosphate (ATP). ATP is the energy currency of all cells. So no matter what you eat, if your body uses it for energy, it all gets turned into ATP.  Since they require less metabolic processing, short- and medium-chain triglycerides are the preferred fuel source when it comes to using fat for energy [*][*].

Sources of Triglycerides

Interestingly, the major source of SCTs is via fermentation of dietary fiber and undigested saccharides by anaerobic bacteria in the gut (it doesn’t come directly from dietary sources). SCTs can provide up to 10% of the total daily metabolic requirement (i.e., a person’s basal metabolic rate or BMR) [*].

Meanwhile, MCTs, LCTs, and VLCTs usually come from dietary sources. For example, LCTs are found in animal fats and olive oil, while MCTs are common in coconut oil, palm oil, and some dairy products. In short, MCTs are more easily used for energy. Why does that matter? Because science shows that eating MCTs can trigger a cascade of other health benefits.

Benefits of MCT Oil

1. Enhances Weight Loss

MCT oil can help you lose weight. First, it helps suppress your appetite by altering the signaling pathways associated with hunger cravings. It does this by increasing the release of leptin and peptide YY, hormones that are responsible for making you feel satisfied and full after a meal [*]. According to a study, individuals who consumed two tablespoons of concentrated MCT oil during breakfast ate less at their next meal compared to their counterparts who had been given plain coconut oil [*]. This experiment showed that MCTs, not other constituents of coconut oil, were the active ingredient. And since coconut oil contains between approximately 50% (or more) MCTs, the researchers wanted to test what effects upping the concentration of MCTs would have on appetite.

Second, other research shows that taking MCT oil can significantly decrease waist circumference and body weight, likely as a result of reduced appetite (same as point #1) and increased thermogenesis. Thermogenesis is the key here. Eating MCT appears to increase energy expenditure (i.e., calories used per day), resulting in improved weight loss. That’s because all things equal, eating MCTs seemed to increase BMR by approximately 45 calories per day [*][*]. It doesn’t seem like a lot at first glance, but it adds up to over 16,000 calories over a year, which is about five pounds.

Finally, more and more research is suggesting a link between gut bacteria and hunger signaling. While the details are still being worked out, the notion seems plausible considering that gut bacteria are entirely reliant on their host (us!) for food. If we don’t eat, they don’t eat. So it makes sense that bacteria might have evolved some ability to influence our hunger pathways.

Researchers have already identified some bacteria-produced metabolites in the human bloodstream. And these metabolites are predicted to interact with the hypothalamus, a part of the brain that is involved in hunger signaling. So, it stands to reason that changing the gut microfauna (or initiating the right signals) through diet (and ingestion of MCTs) could be used to regulate appetite or influence our metabolism [*][*]*]. Not only that, but gut bacteria digest flavonoids that may help prevent gaining body fat [*]. Flavonoids are antioxidants found in vegetables and fruits.

2. Helps Manage Multiple Health Conditions

According to studies, a ketogenic diet and MCT oil can benefit people suffering from epilepsy, Alzheimer’s disease, and autism [*].

A. Epilepsy

A study found that fasting increased the synthesis of ketones, which has been effective at decreasing the rate of epileptic seizures [*]. And in some cases, MCT oil (namely, capric acid) was more effective in controlling seizures than a pharmaceutical anti-epileptic drug [*].

Another study found that capric acid blocked brain receptors that were involved with triggering seizures. Ultimately the researchers didn’t make any groundbreaking claims, but are continuing this exciting research [*]. Nonetheless, it’s pretty clear that eating MCTs can help manage epilepsy as a result of their ability to convert easily into ketones (by the liver).

B. Alzheimer’s Disease

This is a progressive condition that impairs the ability of your brain to use glucose (i.e., sugar). A ketogenic diet high in MCT oil helps provide substrates used to make ketones that serve as an alternative fuel source for the brain and improves its function. In addition, it appears to block a brain receptor that leads to memory loss, thus reducing the rate of progression of the disease [*]. According to one study, a single dose of MCTs improved cognition in individuals suffering from Alzheimer’s disease. Their research showed that a 20g – 70g dose of supplemental MCTs improved Alzheimer’s-related symptoms [*].

C. Autism

Children suffering from autism may benefit from taking MCT oil. According to one study, adding MCT oil to a gluten-free and ketogenic diet significantly improved behaviors in children with autism [*]. But because autism can affect people in so many different ways, the beneficial results of eating MCTs also varies. Hence, this is an active area of research [*].

3. Prevents Bacterial Growth

MCTs have been shown to possess anti-fungal and anti-microbial effects [*][*][*]. Coconut oil contains a significant amount of MCTs and has been shown to decrease the growth of yeast (Candida albicans) by 25%. This strain of yeast can cause skin infections [*].

According to another study, coconut oil substantially decreased the growth of Clostridium difficile, a bacteria that causes life-threatening diarrhea. They’re so effective that MCTs have even been used to reduce the growth of fungus in health centers [*]. Scientists think that the ability of coconut oil to reduce bacterial and yeast growth may be due to the lauric, capric, and caprylic acid in MCTs.

4. Reduces the Risk of Heart Disease

Some factors such as obesity, high cholesterol, and inflammation can increase your risk of heart disease.

So by reducing body weight, which is a key risk factor for heart disease, you can also decrease your risk of heart disease [*]. Another risk factor is high cholesterol. A study found that overweight men who took MCT oil with flaxseed oil and phytosterols for 29 days showed a 12.5% reduction in total cholesterol compared to just 4.7% in participants who only took olive oil [*].

Researchers showed that a diet high in MCTs significantly reduced bad cholesterol and increased good cholesterol levels [*].

Finally, MCT oil has also been shown to decrease an important inflammatory marker called C-reactive protein, which is linked with increased chances of developing heart disease [*]. These are just a few of the many studies linking MCT consumption to a reduced risk of heart disease [*][*].

5. Helps Manage Diabetes

The majority of people suffering from type 2 diabetes are obese or overweight, which is a major symptom of diabetes and contributes to a decreased quality of life. MCTs have been used to increase fat burning and decrease fat storage, thereby improving weight management for obese diabetics [*].

MCTs have also been used by diabetic patients to reduce insulin resistance, waist circumference, and body weight compared to their counterparts who consumed corn oil containing LCTs [*]. Diabetics who ate MCTs prior to injecting insulin required 30% less insulin, suggesting that MCTs improved insulin sensitivity. This result did not occur for diabetics who ingested LCTs instead [*]. Again, it appears MCTs really are the active ingredient and eating just any oil (e.g., corn oil or other oil high in LCT) does not have the same positive health effects as MCT oil.