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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’re 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’re 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.
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).
Please note: Ketones are only made when the body has a shortage of carbohydrates, for instance, if you’re on the keto diet. The brain always prefers to use glucose as fuel in place of ketones.
Because the calories contained in MCTs are more efficiently turned into energy and used by the body, they’re less likely to be stored as fat. That said, further studies are needed to determine their ability to aid weight loss (
Since the MCT is digested quicker than the LCT, it gets to be used as energy first. If there’s an excess of MCT, they too will eventually be stored as fat.
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.
- coconut oil: 55%
- palm kernel oil: 54%
- whole milk: 9%
- butter: 8%
Although the sources above are rich in MCTs, their composition of them varies. 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 (
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% (
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 (
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) (
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.
Coconut and palm kernel oils are rich sources of medium-chain triglycerides, but MCT oil supplements contain much larger amounts.
Although research has turned up mixed results, 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 (
12). However, note that most cooking oils contain both MCTs and LCTs, which may negate any calorie difference.
- 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 (
- Fat storage. Given that MCTs are absorbed and digested more rapidly than LCTs, they’re used as energy first rather than stored as body fat. However, MCTs can also be stored as body fat if excess amounts are consumed (
- Burn calories. Several older animal and human studies show that MCTs (mainly C8 and C10) may increase the body’s ability to burn fat and calories (
14, 15, 16).
- 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 (
However, keep in mind that many of these studies have small sample sizes and don’t take other factors into account, including physical activity and total calorie consumption.
Furthermore, while some studies have found that MCTs could aid weight loss, other studies have found no effects (
According to an older 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 (
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 (
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 (
Another older 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 (
More recent, 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.
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.
Several older human and animal studies suggest that 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 (
Additionally, consuming food containing MCTs instead of LCTs for 2 weeks allowed recreational athletes to endure longer bouts of high-intensity exercise (
Although the evidence seems positive, more recent, high-quality studies are needed to confirm this benefit, and the overall link is weak (
The link between MCTs and improved exercise performance is weak. 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.
MCTs have been linked to lower cholesterol levels in both animal and human studies.
For example, one animal study found that administering MCTs to mice helped reduce cholesterol levels by increasing the excretion of bile acids (
Similarly, an older study in rats linked virgin coconut oil intake to improved cholesterol levels and higher antioxidant levels (
Another older 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 (
Improvements in cholesterol and antioxidant levels may lead to a reduced risk of heart disease in the long term.
One study in 14 healthy men reported that MCT supplements negatively affected cholesterol levels, increasing total cholesterol and LDL (bad) cholesterol, both of which are risk factors of heart disease (
Furthermore, many common sources of MCTs, including coconut oil, are considered saturated fats (
Although studies show that higher saturated fat intake isn’t associated with an increased risk of heart disease, it may be tied to several heart disease risk factors, including higher levels of LDL (bad) cholesterol and apolipoprotein B (
Therefore, more research is needed to understand the complex relationship between MCTs and cholesterol levels, as well as the potential effects on heart health.
Diets high in MCT-rich foods like coconut oil may support healthy cholesterol levels. However, the evidence is mixed.
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 (
What’s more, one animal study found that administering MCT oil to mice fed a high-fat diet helped protect against insulin resistance and inflammation (
However, evidence supporting the use of medium-chain triglycerides to help manage diabetes is limited and outdated. More recent research is needed to determine its full effects.
MCTs may help lower blood sugar levels by reducing insulin resistance. However, more research is needed to confirm this benefit.
MCTs produce ketones, which act as an alternative energy source for the brain and can thus improve brain function in people following ketogenic diets (defined as carb intake less than 50 g/day).
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 (
Overall, the evidence is limited to short studies with small sample sizes, so more research is needed.
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:
- steatorrhea (fat indigestion)
- liver disease
Patients undergoing bowel or stomach surgery may also benefit.
MCTs help treat a number of conditions, including malnutrition, malabsorption disorders, and epilepsy.
Although currently MCT oil doesn’t have a defined tolerable upper intake level (UL), a maximum daily dose of 4–7 tablespoons (60–100 mL) has been suggested (38).
While it’s also not clear what dose is needed to obtain potential health benefits, most studies conducted have used between 1–5 tablespoons (15–74 mL) 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 (5 mL) and increasing intake slowly. Once tolerated, MCT oil can be taken by the tablespoon.
If you’re considering adding MCT oil to your daily routine, talk with a healthcare provider first. It’s also important to get regular blood lipid lab tests to help monitor your cholesterol levels.
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’s thought that high levels of ketones in the blood may increase the risk of ketoacidosis, a very serious condition that can occur in people with type 1 diabetes.
However, the nutritional ketosis a low-carb diet causes is completely different than diabetic ketoacidosis, a very serious condition that a lack of insulin causes.
In people with well-managed diabetes and healthy blood sugar levels, ketone levels remain within a safe range even during ketosis.
There are limited recent studies available that explore the use of MCTs in those with type 1 diabetes. However, some older studies that have been conducted observed no harmful effects (
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’re 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 supplements do not offer.
If you’re thinking about trying MCT oil, talk with a healthcare professional first. They can help you determine if they’re right for you.