Interest in medium-chain triglycerides (MCTs) has grown rapidly over the last few years.

This is partly due to the widely publicized benefits of coconut oil, which is a rich source of them.

Many advocates boast that MCTs can aid weight loss.

In addition, MCT oil has become a popular supplement among athletes and bodybuilders.

This article explains everything you need to know about MCTs.

Medium-chain triglycerides (MCTs) are fats found in foods like coconut oil. They are metabolized differently than the long-chain triglycerides (LCT) found in most other foods.

MCT oil is a supplement that contains a lot of these fats and is claimed to have many health benefits.

Triglyceride is simply the technical term for fat. Triglycerides have two main purposes — they are either burned for energy or stored as body fat.

Triglycerides are named after their chemical structure, specifically the length of their fatty acid chains. All triglycerides consist of a glycerol molecule and three fatty acids.

The majority of fat in your diet is made up of long-chain fatty acids, which contain 13–21 carbons. Short-chain fatty acids have fewer than 6 carbon atoms.

In contrast, the medium-chain fatty acids in MCTs have 6–12 carbon atoms.

The following are the main medium-chain fatty acids:

  • C6: caproic acid or hexanoic acid
  • C8: caprylic acid or octanoic acid
  • C10: capric acid or decanoic acid
  • C12: lauric acid or dodecanoic acid

Some experts argue that C6, C8, and C10, which are referred to as the "capra fatty acids," reflect the definition of MCTs more accurately than C12 (lauric acid) (1).

Many of the health effects described below do not apply to lauric acid.

Summary Medium-chain triglycerides (MCTs) contain fatty acids that have a chain length of 6–12 carbon atoms. They include caproic acid (C6), caprylic acid (C8), capric acid (C10), and lauric acid (C12).

Given the shorter chain length of MCTs, they’re rapidly broken down and absorbed into the body.

Unlike longer-chain fatty acids, MCTs go straight to your liver, where they can be used as an instant energy source or turned into ketones. Ketones are substances produced when the liver breaks down large amounts of fat.

In contrast with regular fatty acids, ketones can cross from the blood to the brain. This provides an alternative energy source for the brain, which ordinarily uses glucose for fuel (2).

Because the calories contained in MCTs are more efficiently turned into energy and used by the body, they are less likely to be stored as fat. That said, further studies are needed to determine their ability to aid weight loss (3).

Summary Due to their shorter chain length, medium-chain triglycerides are more rapidly broken down and absorbed into the body. This makes them a quick energy source and less likely to be stored as fat.

There are two main ways to increase your intake of MCTs — through whole food sources or supplements like MCT oil.

Food sources

The following foods are the richest sources of medium-chain triglycerides, including lauric acid, and listed along with their percentage composition of MCTs (4):

  • coconut oil: 55%
  • palm kernel oil: 54%
  • butter: 8%

Although the sources above are rich in MCTs, their compositions of them vary. For example, coconut oil contains all four types of MCTs, plus a small amount of LCTs.

However, its MCTs consist of greater amounts of lauric acid (C12) and smaller amounts of the capra fatty acids (C6, C8, and C10). In fact, coconut oil is about 42% lauric acid, making it one of the best natural sources of this fatty acid (5).

Compared with coconut oil, dairy sources tend to have a higher proportion of capra fatty acids and a lower proportion of lauric acid.

In milk, capra fatty acids make up 4–12% of all fatty acids, and lauric acid (C12) makes up 2–5% (6).

MCT oil is a highly concentrated source of medium-chain triglycerides.

It’s man-made via a process called fractionation. This involves extracting and isolating the MCTs from coconut or palm kernel oil.

MCT oils generally contain either 100% caprylic acid (C8), 100% capric acid (C10), or a combination of the two.

Caproic acid (C6) is not normally included due to its unpleasant taste and smell. Meanwhile, lauric acid (C12) is often missing or present in only small amounts (7).

Given that lauric acid is the main component in coconut oil, be careful of manufacturers who market MCT oils as "liquid coconut oil," which is misleading.

Many people debate whether lauric acid reduces or enhances the quality of MCT oils.

Many advocates market MCT oil as better than coconut oil because caprylic acid (C8) and capric acid (C10) are thought to be more rapidly absorbed and processed for energy, compared with lauric acid (C12).

Summary Food sources of MCTs include coconut oil, palm kernel oil, and dairy products. Yet, their MCT compositions vary. Also, MCT oil boasts large concentrations of certain MCTs. It often contains C8, C10, or a mix of the two.

The best source for you depends on your goals and desired intake of medium-chain triglycerides.

It’s not clear what dose is needed to obtain potential benefits. In studies, doses range from 5–70 grams (0.17–2.5 ounces) of MCT daily.

If you aim to achieve overall good health, using coconut oil or palm kernel oil in cooking is probably sufficient.

However, for higher doses, you might want to consider MCT oil.

One of the good things about MCT oil is that it has virtually no taste or smell. It can be consumed straight from the jar or mixed into food or drinks.

Summary Coconut and palm kernel oils are rich sources of medium-chain triglycerides, but MCT oil supplements contain much larger amounts.

There are several ways in which MCTs may aid weight loss, including:

  • Lower energy density. MCTs provide around 10% fewer calories than LCTs, or 8.4 calories per gram for MCTs versus 9.2 calories per gram for LCTs (8).
  • Increase fullness.One study found that compared with LCTs, MCTs resulted in greater increases in peptide YY and leptin, two hormones that help reduce appetite and increase feelings of fullness (9).
  • Fat storage. Given that MCTs are absorbed and used more rapidly than LCTs, they are less likely to be stored as body fat (8).
  • Burn calories. Animal and human studies show that MCTs (mainly C8 and C10) may increase the body's ability to burn fat and calories ( 10, 11, 12).
  • Greater fat loss. One study found that an MCT-rich diet caused greater fat burning and fat loss than a diet higher in LCTs. However, these effects may disappear after 2–3 weeks once the body has adapted (13).
  • Low-carb diets. Very low-carb or ketogenic diets are effective ways to lose weight. Given that MCTs produce ketones, adding them to your diet can increase the number of carbs you can eat while staying in ketosis.

Nevertheless, while many studies have found that MCTs can aid weight loss, other studies have found no effects (14).

In a review of 21 studies, 7 evaluated fullness, 8 measured weight loss, and 6 assessed calorie burning.

Only 1 study found increases in fullness, 6 observed reductions in weight, and 4 noted increased calorie burning (15).

In another review of 12 animal studies, 7 reported a decrease in weight gain and 5 found no differences. In terms of food intake, 4 detected a decrease, 1 detected an increase, and 7 found no differences (16).

In addition, the amount of weight loss caused by MCTs was very modest.

A review of 13 human studies found that, on average, the amount of weight lost on a diet high in MCTs was only 1.1 pounds (0.5 kg) over 3 weeks or more, compared with a diet high in LCTs (14).

Another 12-week study found that a diet rich in medium-chain triglycerides resulted in 2 pounds (0.9 kg) of additional weight loss, compared with a diet rich in LCTs (17).

Further high-quality studies are needed to determine how effective MCTs are for weight loss, as well as what amounts need to be taken to reap benefits.

Summary MCTs may aid weight loss by reducing calorie intake and fat storage and increasing fullness, calorie burning, and ketone levels on low-carb diets. Still, a high-MCT diet’s weight loss effects are generally quite modest.

MCTs are thought to increase energy levels during high-intensity exercise and serve as an alternative energy source, sparing glycogen stores.

This may boost endurance and offer benefits for athletes on low-carb diets.

One animal study found that mice fed a diet rich in medium-chain triglycerides did much better in swimming tests than mice fed a diet rich in LCTs (18).

Additionally, consuming food containing MCTs instead of LCTs for 2 weeks allowed recreational athletes to endure longer bouts of high-intensity exercise (19).

Although the evidence seems positive, more high-quality studies are needed to confirm this benefit, and the overall link is weak (20).

Summary The link between MCTs and improved exercise performance is weak, and more studies are needed to confirm these claims.

The use of medium-chain triglycerides and MCT oil has been associated with several other health benefits.

Cholesterol

MCTs have been linked to lower cholesterol levels in both animal and human studies.

For example, calves consuming MCT-rich milk had lower cholesterol than calves fed LCT-rich milk (21).

One study in rats linked virgin coconut oil intake to improved cholesterol levels and higher antioxidant levels (22).

A study in 40 women found that consuming coconut oil along with a low-calorie diet reduced LDL (bad) cholesterol and increased HDL (good) cholesterol, compared with women consuming soybean oil (23).

Improvements in cholesterol and antioxidant levels may lead to a reduced risk of heart disease in the long term.

However, it’s important to note that some older studies report that MCT supplements had either no effects — or even negative effects — on cholesterol (24, 25).

One study in 14 healthy men reported that MCT supplements negatively affected cholesterol levels, increasing total cholesterol and LDL cholesterol (25).

Summary Diets high in MCT-rich foods like coconut oil may support healthy cholesterol levels. However, the evidence is mixed.

Diabetes

MCTs may also help lower blood sugar levels. In one study, diets rich in MCTs increased insulin sensitivity in adults with type 2 diabetes (26).

Another study in 40 individuals with excess weight and type 2 diabetes found that supplementing with MCTs improved diabetes risk factors. It reduced body weight, waist circumference, and insulin resistance (27).

However, evidence supporting the use of medium-chain triglycerides to help manage diabetes is limited. More research is needed to determine its full effects.

Summary MCTs may help lower blood sugar levels by reducing insulin resistance. However, more research is needed to confirm this benefit.

Brain function

MCTs produce ketones, which act as an alternative energy source for the brain and can thus improve brain function in people following very low-carb diets.

Recently, there has been more interest in the use of MCTs to treat or prevent brain disorders like Alzheimer's disease and dementia (28).

One major study found that MCTs improved learning, memory, and brain processing in people with mild to moderate Alzheimer's disease. However, this effect was only observed in people who didn’t have the APOE4 gene variant (29).

Overall, the evidence is limited to short studies with small sample sizes, so more research is needed.

Summary MCTs may improve brain function in people with Alzheimer's disease who have a particular genetic makeup. More research is needed.

Other medical conditions

Because MCTs are an easily absorbed and digested energy source, they've been used for years to treat malnutrition and disorders that hinder nutrient absorption.

Conditions that benefit from medium-chain triglyceride supplements include diarrhea, steatorrhea (fat indigestion), and liver disease. Patients undergoing bowel or stomach surgery may also benefit.

Evidence also supports the use of MCTs in ketogenic diets treating epilepsy (30).

The use of MCTs allows children suffering from seizures to eat larger portions and tolerate more calories and carbs than classic ketogenic diets allow (31).

Summary MCTs help treat a number of conditions, including malnutrition, malabsorption disorders, and epilepsy.

MCT oil appears to be safe for most people.

It’s not clear what dose is needed to obtain potential health benefits, but many supplement labels suggest 1–3 tablespoons daily.

There are currently no reported adverse interactions with medications or other serious side effects.

However, some minor side effects have been reported, including nausea, vomiting, diarrhea, and an upset stomach.

These can be avoided by starting with small doses, such as 1 teaspoon, and increasing intake slowly. Once tolerated, MCT oil can be taken by the tablespoon.

Type 1 diabetes and MCTs

Some sources discourage people with type 1 diabetes from taking medium-chain triglycerides due to the accompanying production of ketones.

It is thought that high levels of ketones in the blood may increase the risk of ketoacidosis, a very serious condition that can occur in type 1 diabetics.

However, the nutritional ketosis caused by a low-carb diet is completely different than diabetic ketoacidosis, a very serious condition caused by a lack of insulin.

In people with well-controlled diabetes and healthy blood sugar levels, ketone levels remain within a safe range even during ketosis.

There are limited studies available that explore the use of MCTs in those with type 1 diabetes. However, some have been conducted and observed no harmful effects (32).

Summary MCT oil is safe for most people, but there are no clear dosage guidelines. Start with small doses and gradually increase your intake.

Medium-chain triglycerides have many potential health benefits.

While they are not a ticket to dramatic weight loss, they may provide a modest benefit. The same can be said for their role in endurance exercise.

For these reasons, adding MCT oil to your diet may be worth a try.

However, remember that food sources like coconut oil and grass-fed dairy provide additional benefits that are not offered by supplements.