MCT Science

MCT is a very unique saturated fat. The common misconception is that all saturated fats are bad and should therefore be avoided. However, medium chain fatty acids -a unique group of saturated fat- have special properties that distinguish them from longer chain saturated fats (i.e. Omega-3), which make up 99% of the saturated fats in the typical Western diet.


Medium Chain Triglycerides (MCTs) can be converted to ketones in our liver within minutes of ingestion. Compared to carbohydrates, ketones are considered to be a more rapidly metabolized superior fuel for immediate use by the brain, muscles and other organs. MCTs are metabolized in the mitochondria for energy and provide significant health benefits such as increased energy and performance, weight management, and improved brain function and gut health.


MCTs first made their way to the market as “super fats” in the 1950s. Then they disappeared almost completely until recently, now with increased popularity. This popularity has come particularly from coconut oil. Besides MCT itself, coconut oil is the richest source of medium chain triglycerides with an average MCT content of 60%. Palm kernel oil contains about 55% MCTs, but palm oil farms can cause environmental destruction. Thus, we source MCTs from sustainable palms, or solely from coconuts, though there is a global shortage as of April 2017.


Back in the 1950s, MCTs were recognized as a unique source of energy, namely for people who hade trouble absorbing fat. Now we realize it’s also a unique source of energy for those who absorb glucose abnormally, which can lead to cognitive disorders. MCTs are particularly useful for the brain and muscles to provide quickly available and lasting energy.


So what exactly is an MCT?

All fats are composed of carbon and hydrogen; the variations in the number of carbon atoms is reflected in the molecule`s name. Fatty acids with 5 or fewer carbon atoms are called short chain fatty acids (i.e. butyrate), medium chains have 6-12 and long chain fatty acids (i.e. omega 3) have more than 12 carbon atoms. MCTs are constructed by three medium chain fatty acid molecules linked together by a glycerol molecule. Being fully saturated, MCTs exhibit a similar structural stability and resistance to oxidation as their longer-chain cousins. Usually, MCT oils are a mix of different types of medium chain fatty acids containing primarily C:8 (eight carbon atoms), but also some C:10, as well as C:6 and C:12. It is possible to buy pure C:8 over the counter, which has the highest conversion to ketone bodies (Vandenberghe et al 2016) and, thus, highest potential for the unique functional and therapeutic properties. Let`s see how and why they work.


MCTs are easily digestible, beneficial fat metabolized in the liver, rather than processed through digestion like most other foods (Fig.1). This means they don’t require digestive enzymes (lipases and bile salts) to be broken apart, nor packaged into lipoprotein particles that transport dietary lipids from the intestines to other locations in the body (called chylomicrons). Instead, MCTs are easily absorbed directly from the intestine and taken to the liver, rather than into the lymphatic system. Unlike Long Chain Triglycerides (LCTs), MCTs do not require carnitine for oxidation and easily pass through the mitochondrial membrane without enzymes or a shuttle system where they enter metabolic pathways to produce acetyl-CoA, which is oxidized by way of the tricarboxylic acid cycle (aka ATP cycle or energy cycle) or further converted to ketone bodies called beta-hydroxybutyrate and acetoacetate. This immediate penetration of the mitochondrial membrane is important because it provides faster energy. Additionally, it’s potentially superior to other energy sources—such as carbohydrates--because it provides more energy. Alternatively, acetyl CoA can be transported into the liver cell and used for new synthesis of long chain fatty acids (From Bach and Babayan, 1982).


MCTs also enhance thermogenesis and fat oxidation, which suppresses the deposition and accumulation of body fat. You may ask how is it possible that you can eat more calories in the form of MCT vs. LCT and gain less fat? The answer is again in the different metabolism. MCTs are quickly oxidized by the liver and only a very small percentage (<2%) has been shown to contribute to fat storage (Yost et al 1994). MCTs provide about 8.4 kcals per gram compared with 9.2 kcal for LCTs, and MCTs are more directly converted to fuel for immediate use, instead of being stored as fat. For these reasons, MCTs are useful for people who have high metabolic demands, such as athletes, those recovering from surgery, severe injuries or burns, or cancer cachexia (aka muscle wasting).


The other great advantage to MCTs is that our body readily converts MCTs to ketone bodies for use as fuel if no carbs are available. These effects might remind you of the ketogenic diet which helps your body produce and burn ketones as fuel, rather than carbohydrates. MCTs can be used as a clean-burning fuel without having to reduce your carb intake as drastically as required on a ketogenic diet. Another benefit is that MCTs don’t need insulin to help them cross cell membranes, including neuronal membranes. Instead, they use protein transporters, which allow them to enter cells that have become insulin resistant. This is a crucial point because MCTs are an immediate fuel source for brain and muscle, even for those unable to effectively use carbohydrates as fuel. Those with diabetes, Alzheimer’s and other chronic conditions are characterized by insulin resistance and an inability to process carbohydrates. Ketones from MCTs bypass this fuel problem.


What are other ingredients that go well with MCTs? Are there specific MCTs that are better than others? Why potentially combine with BHB? Why use in coffee? Are there potential synergies with caffeine?

Caffeine significantly increases ketone levels (Cunnane 2017, in press). So, combined with MCT oil, the theoretical effect could be complementary. While this combination is currently under clinical investigation, millions of people have already adopted the combination in the form of MCT in coffee! This is the famous “Bullet Proof” coffee people are talking about. Some prefer pure C:8 MCT due to its higher conversion to ketones, as well as wide reporting of lower GI distress. Additionally, MCT combined with BHB increases and sustains the elevation of blood ketones better than BHB or MCT alone. This combination is gaining extremely wide acceptance in powder drink mixes.


Along with this easy absorption, MCTs appear to enhance absorption of other substances such as calcium, magnesium and amino acids, potentially providing a nutritional advantage for those who have an immature bowel, such as premature newborns, and people with impaired fat metabolism and malabsorption syndromes.


What are the benefits?

MCTs have a wide range of health and performance benefits, especially those associated with nutritional ketosis, but without having to follow strict dietary restrictions. Some of those benefits include fat loss, energy and performance, cognitive and neurological advantages, controlling blood sugar, infant nutrition, cardiovascular health and gut and immune health.


MCTs for Energy and Performance

Since MCTs are processed in the liver, they are absorbed quickly and provide fast and sustained energy. MCTs move passively via the hepatic portal system to the liver without the need for a longer digestive process. Unlike almost all other foods, MCTs do not require energy to be absorbed, stored or used in the body, making them an almost perfect source of natural energy. MCTs also have been shown to increase physical endurance, and coupled with the increased immediate energy availability, would be useful to those who desire to enhance their athletic performance, as well as the elderly or frail who wish to have more energy.


The effect of chronic administration of MCTs on swimming endurance (swim capacity) was tested in laboratory mice. The mice were fed a diet containing MCTs for six weeks and they were subjected to forced swimming every two days in a current water pool until exhaustion. The study showed that ketone body utilization associated with the chronic administration of an MCT-containing diet enhanced their swim capacity.


Another study showed beneficial effect on the performance of cyclists. Six endurance-trained cyclists rode for 2 hours at 60% of peak O2 uptake and then performed a simulated 40-km time trial. The results showed improved time performances during the 40km trials when the cyclists consumed MCTs in addition to a low glucose beverage.


MCTs for Cognitive Improvement and for Neurological Disorders

Studies suggest a link between metabolic disorders and cognitive decline. Since glucose metabolism becomes less efficient in the brain with age, it is likely that MCT supplementation may be able to improve brain function in elderly people with or without dementia symptoms. A study performed on dogs show that MCT supplementation can improve age-related cognitive decline by providing an alternative source of brain energy that can at least partly compensate for age-associated decrease in energy metabolism (Cunnane 2017).


Consuming MCTs improved cognition without elevating blood glucose levels in patients with type 1 diabetes, as well. In this case MCTs offer the therapeutic advantage of preserving brain function under hypoglycemic conditions without causing deleterious high blood glucose levels. Study subjects had impaired cognitive performance in tests of immediate verbal memory, delayed verbal memory, verbal memory recognition and several other cognitive tests when blood glucose decreased to lower than normal levels after placebo ingestion (Fig. 3). When compared with ingestion of the placebo drink, MCTs prevented the decline in cognitive performance during hypoglycemia in tests of immediate verbal memory, delayed verbal memory, verbal memory recognition and other cognitive tests.


In several studies ketones have been shown to be neuroprotective. Ketones appear to be the preferred source of energy for the brain in Alzheimer’s and Parkinson’s because certain neurons have become insulin resistant or have lost the ability to efficiently utilize glucose. As a result, neurons slowly die if no other form of energy is available.


In recent years, taking MCT and coconut oil has become more common in those with neurodegenerative diseases in which impaired glucose metabolism affects areas of the brain and/or peripheral nervous system. The dietary ketosis induced by the consumption of MCTs may effectively bypass the problem of insulin resistance and restore metabolic function in cells that are glucose-starved. Studies with only a few Alzheimer’s disease and mild cognitive impairment patients taking MCT oil have shown improved memory and cognitive performance in nearly half of people who were given MCT oil. Other studies with more participants taking MCT oil or the coconut and MCT oil combination are currently underway.


MCTs For Diabetics

Another unique property of MCTs is enhanced glucose utilization, mediated by insulin. This advantage occurs both in diabetics and non-diabetics, thereby potentially providing improved glucose control in diabetics and those with insulin resistance. And this leads us back to ketones serving as an alternative fuel for the brain, skeletal and cardiac muscle, and other organs. 


Glucose is not always available to burn as fuel, such as during prolonged fasting, running a marathon, when glucose reserves have been exhausted, or when glucose is ineffectively transported across insulin resistant cells... In these cases, ketones—from MCT, for example--can be readily used as alternative fuel. In addition, MCT oil has been shown to protect cognition in type 1 insulin-dependent diabetics during severe hypoglycemic episodes.


MCTs for Infant Nutrition

Since MCTs are easier to digest and metabolize, they are the “perfect” fat source for infants whose digestive tracts aren’t fully developed. Interestingly, human breastmilk and milk fat of other mammals such as goats and cows, contain approximately 23% and 14% MCTs, respectively. MCTs can also be found in cheese, butter, as well as in other dairy.


Scientists have recognized the importance of this readily digestible source of fatty acids in mother’s milk long ago and today almost every infant formula on the US market has MCT oil or a corresponding natural source of MCTs, such as coconut oil.


MCTs for Cardiovascular Health

MCTs can offer great benefit to heart health, as well. Previous studies have shown that MCTs help lower total lipid levels and improve cardiovascular health. Those people who regularly consume coconut oil have a lower incidence of heart attack compared to those who do not consume it. The effect can be attributed to the MCTs in the coconut oil. (Kaunitz et al 1959; Stewart et al 1978; Bach and Babayan 1982).


MCTs for Gut and Immune Health


First of all, because of the above-mentioned mechanisms, MCT oil is often more easily digested by those struggling to digest other types of fat, such as those with malabsorption, leaky gut, Crohn’s disease or lacking a gallbladder. Ketone bodies have also been shown to decrease inflammatory markers, such as IL-6, which may further improve these conditions (Forsythe et al. 2008; Ruskin et al. 2009; Paoli et al 2015).


There are other properties of MCTs that appear to be beneficial to health. For example, lauric acid (C:12) is known to have anti-microbial and antibacterial properties that help to combat various bacteria (for example the bacteria that causes ulcers), yeast and protozoa, although regular coconut oil, which is roughly 50% lauric acid, may be preferable to MCT oil for this application. MCTs also help balance gut bacteria by offering the digestive system a break, because they are so easily utilized by the body, they improve gut health over time. This is important because of recent research tying a healthy gut microbiome to improved cognitive function (Mayer et al. 2014; Galland 2014). Ingesting MCTs, or even combining them with the prebiotic fiber, acacia fiber, is the latest science on this “gut-brain axis” of cognitive health.


The same antiviral and antibacterial properties make MCTs beneficial for the immune system, as well. Healthy fats are important for proper immune function, and since MCTs can be more easily used by the body, this may be especially beneficial for those who have trouble absorbing fats and who struggle with impaired immune function.


What are the doses typically used?

Before specifically mentioning dose, it’s important to note that many are using MCT and coconut oil almost interchangeably. But MCT has several notable advantages over coconut oil. At room temperature, MCT oil is liquid, while coconut oil is a solid. MCT is tasteless, so its more versatile, and those who don`t like the taste of coconut can still use MCT oil. Anecdotally, MCT also promotes more rapid energy metabolism than coconut oil. So, depending on the goal to be achieved, MCT oil may be more effective than coconut oil. And doses do vary.


For an average healthy person, the daily dose of MCTs could be in the range of 30-90ml/day. This amount, if we consume it throughout the day, has been shown anecdotally to induce dietary ketosis without restricting carbohydrate. For those with neurological diseases -such as Alzheimer’s disease- using MCTs to supplement their diet was found to be beneficial when using a daily dose of 20 grams (4 tablespoon).


MCT’s effect on blood ketone levels can be measured in urine, breath or blood testing. It is mostly commonly measured in the blood using the Precision Xtra from Abbott Labs. It should be noted that this blood ketone meter only measures D-Beta-Hydroxybutyrate, not all ketones such as acetone, acetoacetate and L-Beta-Hydroxybutyrate. The ketone level should be measured about one hour after taking the MCT oil and, anecdotally, it should ideally reach around 0.5mmol/L in order to experience the hunger suppression and fat burning effect commonly reported from those taking MCTs.


GI tolerability and absorption will vary between each person. The tolerance level can vary between 10ml/day to 100ml/day in some individuals. Most importantly, taking MCTs should be started at a low dose (e.g. 1 teaspoon, which is about 5ml and gradually increase the dose over a couple weeks until the desired blood ketone level and effect are achieved. Too much MCT will not harm you; it will temporarily cause diarrhea and gastrointestinal discomfort. In summary, everybody will need to find the right dose for their individual purpose and tolerance level.


What are potential downsides?

The potential downsides of taking MCTs are both environmental and digestive.


Many continue to search out MCT oils that are sourced only from coconut oil or sustainable and rainforestfriendly palm oil. In recent years, the palm oil industry caused intense deforestation to make room for palm production. This negatively impacted local inhabitants, as well as drove animals out of their natural habitats, such as the orangutan and Sumatran tiger, which are both endangered. When buying MCT oil, we source only from sustainable palm or from coconut.


The digestive concerns are less serious and easily avoidable. The main advice to follow is to start introducing MCT oil into your diet slowly. It is quickly used by the body, so it can potentially lead to diarrhea, or similar, temporary digestive disturbances. Increase your tolerance by gradually increasing the dose. MCT oils can be consumed every day. It is probably a good idea to start with 1/2 to 1 teaspoon (~5ml) and slowly work up toward higher doses over a couple weeks until it starts causing loose stools and gastrointestinal side effects. Once your tolerance increases, you can slowly increase that amount to 4 tablespoons of MCT oil per day, if needed.


If you don`t take the MCTs for a while you will have to restart, and adjust your body again starting with a small amount. It can help to improve your tolerance if you use the powdered form in shakes, coffee or home baked goods. If you use an MCT powder, be careful to use powders with low-glycemic carriers. In other words, avoid MCT powders containing maltodextrin or corn starch. One example of a clean, low-glycemic carrier for MCT powder is acacia fiber, which is used in goMCT™ powder.



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