Overview

Medium-chain triglycerides (MCTs) are fatty acids that your body can use to make energy. Your body turns MCTs into energy using a process called ketosis. As a result, some MCT products are called “keto supplements.” They are available over the counter as oils, powders, and capsules. But the benefits of taking MCTs for any use are not well defined. Common side effects include diarrhea, nausea, and upset stomach. Before taking MCTs, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What are medium-chain triglycerides (MCTs) used for?

MCTs are used as a source of calories. They may also be used for various other reasons, although their benefits are not well defined. Some common reasons for using MCTs include the following.

• Diabetes
• High triglyceride levels
• Weight loss
• To improve memory and thinking skills

Note: The FDA has not reviewed MCTs for safety and effectiveness. Learn more about dietary supplements here.

MCTs are available over the counter as a dietary supplement. A specific MCT (triheptanoin) is also available as a prescription medicine that is used to treat certain rare metabolic disorders. See Dojolvi to learn more.

How do MCTs work (mechanism of action)?

The fatty acids (fat) in the foods that you eat come in three different lengths: short, medium, and long. Medium-chain triglycerides (MCTs) are medium-length fats. Some foods, such as coconut oil, contain MCTs. However, these foods also contain short and long fatty acids. MCT products only contain three specific medium-length fatty acids: caprylic acid, capric acid, and/or lauric acid. Each of these fatty acids may have slightly different effects in the body.

Your body usually uses sugar (carbohydrates) as a source of energy. But it is also able to use fat as a source of energy, especially at times when there is not enough sugar available. Using a process called ketosis, your body turns fat into ketone bodies. Your heart, brain, and other organs are able to use ketone bodies as a source of energy. Your body may enter ketosis during a very long workout or if you are following a very low carbohydrate diet such as the ketogenic diet.

Most of the fats in the foods that you eat are long fatty acids, which are hard for your body to break down into ketone bodies (energy). MCTs, on the other hand, can be broken down by your body much faster. As a result, taking MCTs by mouth can help your body enter into ketosis, increasing the levels of ketone bodies in your blood.

High levels of ketone bodies are thought to be related to metabolic health. But it is not clear if taking MCTs can help improve metabolic health. Although some studies show that MCTs may help lower the levels of sugar in your blood, other studies show no benefit. And while some studies show that MCTs can help lower triglyceride levels, other studies show that they may actually increase triglyceride levels.

MCTs are a source of calories and energy. Some people use MCTs to replace other calories in their diet. But it is not clear if taking MCTs can reduce your appetite or increase weight loss. It is possible that MCTs may work for some people better than others, but it is not clear who is most likely to benefit.

How should I store MCTs?

You should store MCTs according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of MCTs?

The most common side effects of MCTs are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.

• Diarrhea
• Nausea
• Upset stomach

There may be other side effects of MCTs that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of MCTs?

While less common, the most serious side effects of MCTs are described below, along with what to do if they happen.

Severe Allergic Reactions. MCTs may cause allergic reactions, which can be serious. Stop using MCTs and get help right away if you have any of the following symptoms of a serious allergic reaction.

• Breathing problems or wheezing
• Racing heart
• Fever or general ill feeling
• Swollen lymph nodes
• Swelling of the face, lips, mouth, tongue, or throat
• Trouble swallowing or throat tightness
• Itching or skin rash
• Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
• Nausea or vomiting
• Dizziness, feeling lightheaded, or fainting
• Stomach cramps
• Joint pain

Precautions

Who should not use MCTs?

Allergies to Ingredients. People who are allergic to any of the following should not use MCTs.

• Capric acid
• Caprylic acid
• Lauric acid
• Medium-chain fatty acids (MCFAs)
• Medium-chain triglycerides (MCTs)
• Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific MCT products they stock.

What should I know about MCTs before using them?

MCTs are a dietary supplement. They cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are using, or use it as recommended by your health care provider.

Keep MCTs out of the reach of children.

MCTs may be found in products that are marketed as “keto supplements.” These supplements may include many ingredients that have different effects in the body. Read the product label closely to see which ingredients it contains.

If you are using MCT powder, use an appropriate measuring device to measure the powder, such as the device included with the product. Read the label carefully, and measure the amount stated on the label.

If you are using MCT oil, use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose.

Most MCT oils and powders should be added to foods or thick drinks, such as smoothies. Taking MCTs with food can help reduce the risk of certain side effects.

The FDA has not tested MCTs products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using MCTs?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if MCTs are right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions.Tell your health care provider if you have any of the following.

• Diabetes
• Liver problems
• Pancreatic insufficiency
• Follow a very low-carbohydrate diet, such as the ketogenic diet

Other Medicines and Supplements.MCTs may interact with other medicines and supplements. Before taking MCTs, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how MCTs could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. MCTs pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Do MCTs interact with foods or drinks?

Taking MCTs with food may help reduce certain side effects. But changing the type of food you eat may change the way MCTs work. When possible, take MCTs with a similar type of food each day. If you have any questions, speak with a health care provider.

It is unknown if drinking alcohol will affect MCTs.

Do MCTs interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking MCTs.

• Divalproex sodium, valproate sodium (Depakote and others), or valproic acid, which are medicines used for seizures and other conditions
• Dojolvi (triheptanoin) or any other product that contains MCTs
• Orlistat (Alli, Xenical), which is a medicine used for weight loss

The interactions between MCTs and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with MCTs is incomplete. Always check with your health care provider before taking MCTs with any medicines.

Dosing

What should I do if I accidentally use too much MCTs?

If you or someone else has used too much MCTs, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

MCTs come in many forms, including oils, capsules, and powders. The dose may vary depending on your reason for use. Read the product label closely, and speak with a health care provider about how to take MCTs safely. Do not take double or extra doses, even if you miss a dose.