Medium-chain triglycerides (MCTs)
Medium-chain triglycerides (MCTs) are found in foods such as coconut oil and dairy products. Some studies suggest that MCTs can increase muscle strength, improve cognitive function, and help control weight, but these claims require further research to confirm.
Medium-chain triglycerides (MCTs) are most commonly used for cardiovascular health. MCTs cover weight loss and maintenance, Alzheimer's disease, and six other diseases and goals.
Dosage information
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Medium-chain triglycerides are most commonly used for cardiovascular health.
Medium-chain triglycerides (MCTs) are lipids (fats) composed of three medium-length fatty acids (6 to 12 carbon atoms) linked to a glycerol backbone. MCTs are mainly divided into four types, each with a different fatty acid chain length.
- Hexanoic acid (hexane acid) has a fatty acid chain length of 6 carbon atoms.
- Octanoic acid (octanoic acid) has a fatty acid chain length of 8 carbon atoms.
- Decanoic acid (decanoic acid or decenoic acid) has a fatty acid chain length of 10 carbon atoms.
- Lauric acid (dodecanoic acid) has a fatty acid chain length of 12 carbon atoms.
Dairy products such as coconut oil, palm kernel oil, and butter contain significant amounts of medium-chain triglycerides (MCTs) per serving. Specialized MCT oil supplements also contain MCTs.
Medium-chain triglycerides (MCTs) can be rapidly digested and converted into energy, bypassing the usual fat digestion process. However, people with a rare genetic disorder— medium-chain acetylglucosidase A dehydrogenase (MCAD) deficiency—are unable to effectively break down MCTs, which can lead to serious health problems.
Muscle strength and function
Some randomized controlled trials suggest that daily supplementation with medium-chain triglycerides can enhance muscle strength and function through exercise in adults who have or are at risk of sarcopenia and asthenia.
Cognitive performance
Some observational studies have shown that higher serum octanoic acid (OCA) levels are associated with a reduced risk of mild cognitive impairment. Some small randomized controlled trials have shown that daily supplementation with medium-chain triglycerides (MCTs) can improve cognitive function (working memory and executive function) in adults without known health problems. Some evidence suggests that daily MCT supplementation can improve cognitive function in individuals with mild to moderate Alzheimer's disease. However, this phenomenon has only been observed in individuals with the APOE4-/- genotype, i.e., those who do not carry the ε4 allele of the apolipoprotein E (APOE) gene, which makes them more susceptible to Alzheimer's disease. This means that current evidence does not show that medium-chain triglycerides (MCTs) are beneficial to cognitive function in populations with a high genetic risk of Alzheimer's disease (those carrying the ε4 allele of the APOE gene). Furthermore, meta-analyses of studies on the effects of MCTs on dementia show significant heterogeneity in effect sizes among studies, and currently do not support the use of MCTs for the treatment or prevention of Alzheimer's disease. In general, research in this field also carries a high risk of bias due to poor research design and conflicts of interest.
Fat oxidation
Small, randomized controlled trials have also shown that daily supplementation with medium-chain triglycerides (MCTs) can increase fat oxidation rates during high-fat meals and low -intensity exercise (in males with no known health conditions). However, these studies typically compare MCTs to carbohydrates or a placebo, rather than to other types of fats such as long-chain triglycerides. Therefore, the observed effects may not be specific to medium-chain triglycerides .
weight
Several studies have also explored the effects of medium-chain triglycerides (MCTs) on body composition and weight. Some meta-analyses have found that MCT supplementation can reduce weight, but the effect is very small and varies greatly between studies. Furthermore, these studies are small in scale, limited in number, and most are influenced by conflicts of commercial interest.
Energy intake
Although medium-chain triglycerides (MCTs) do not appear to affect appetite or circulating concentrations of gut hormones, a meta-analysis found that the potential effect of MCTs on weight may stem from a modest reduction in daily energy intake. However, this meta-analysis, summarizing various study types, including acute and chronic MCT supplementation and diets containing different doses of MCT, confirmed this effect. Therefore, more high-quality trials and meta-analyses are needed to understand the impact of MCTs on weight regulation.
Limited research on the long-term safety and optimal dosage of medium-chain triglycerides (MCTs) in humans underscores the need for further investigation. However, MCTs are generally considered safe for consumption with low toxicity. Nevertheless, some supplement studies have reported side effects such as nausea, diarrhea, and abdominal discomfort.
The no-observed-adverse-effects (NOAEL) range for medium-chain triglycerides (MCTs) is 3 to 5 grams per kilogram of body weight per day. However, patients receiving intravenous MCTs (such as those receiving total parenteral nutrition (TPN)) have tolerated doses of 3 to 9 grams per kilogram of body weight per day for several months without adverse effects. To illustrate, a standard 2,500-calorie diet, with 30% of calories from dietary fat, contains approximately 80 grams of fat per day. If all 80 grams of fat came from MCTs, a 70-kilogram person would have a daily MCT intake of approximately 1.1 grams per kilogram of body weight, well below the NOAEL range. However, the typical intake of MCTs in a regular diet is only 2 to 9 grams per day, and even those taking daily MCT supplements may only consume 5 to 20 grams per day; these ranges are also well below the 210 to 350-gram no-observed-adverse-effects (NOAEL) for a 70-kilogram (154-pound) person.
It should also be noted that, overall, the evidence supporting the benefits of MCT carries a moderate to high risk of bias due to the limited number of studies, small sample sizes, and/or poor methodological quality (e.g., lack of control groups), and the fact that these studies were funded/written by manufacturers of MCT-containing supplements.
Cognitive performance
In a fasting state, intake of medium-chain triglycerides (MCTs) rapidly increases serum ketone body (β-hydroxybutyrate, acetic acid, and acetone) concentrations. Similarly, regular MCT supplementation also increases serum ketone body concentrations. Since ketone bodies can serve as an alternative energy source for the brain when glucose supply is insufficient, some studies suggest that providing the brain with a source of ketone bodies may be a mechanism by which MCTs enhance cognitive function. Preclinical studies in rodents support this view, and some clinical trials have indeed found that exogenous ketone body supplementation can improve cognitive dysfunction under metabolic stress (e.g., fasting, hypoxia, or exercise). However, the effects vary considerably, and some clinical trials have not found any effect of exogenous ketones on cognitive function.
Muscle strength and function
The mechanism by which MCT-enhanced exercise leads to increased muscle strength is not fully understood, but it may involve inhibiting the expression of the MuRF-1 enzyme (thereby stimulating muscle protein synthesis and inhibiting muscle protein breakdown), increasing the concentration of plasma acyl-glucan-releasing peptide (thereby stimulating growth hormone secretion), or activating the sympathetic nervous system and upregulating peroxisome proliferator- 1.
weight
The mechanisms by which medium-chain triglycerides (MCTs) affect body weight may involve changes in appetite hormone secretion, reduced energy intake, or increased lipid oxidation, but not all studies have confirmed these effects. Evidence from rodent studies and in vitro experiments also suggests that MCTs may promote browning of white adipose tissue, thereby enhancing lipolysis and energy expenditure. However, these mechanisms are not fully understood and require further investigation.
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Nutritional Supplement Recommendations
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NOW Foods, Sports, Medium Chain Triglyceride Oil, 1,000 mg, 150 Softgels
Each capsule contains 1000 mg of MCT oil (medium-chain triglycerides) , which is easily absorbed and provides energy quickly, helping to support metabolism and physical performance. It is an excellent choice for daily energy and sports nutrition supplementation.
NOW Foods, Sports, MCT Oil, Original Flavor, 16 fl oz (473 ml)
Contains MCT oil (medium-chain triglycerides) , which is easily absorbed and provides energy quickly, helping to support metabolism, physical performance, and daily energy replenishment. It can be added to beverages or meals.
California Gold Nutrition, Sports Series, Organic Medium Chain Triglyceride Oil, Plain, 12 fl oz (355 ml)
Contains organic MCT oil (medium-chain triglycerides) , which is easily absorbed and provides energy quickly, helping to support metabolism, physical performance, and daily energy replenishment. It can be added to beverages or meals.
Nature's Way, Organic Medium Chain Triglyceride Oil, 30 fl oz (887 ml)
Contains organic MCT oil (medium-chain triglycerides) , which is easily absorbed and provides energy quickly, helping to support metabolism and daily energy replenishment. It can be added to beverages or meals.
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Dosage information
Dosage form
Common dosage forms of medium-chain triglycerides (MCTs) include:
MCT oil
powder
Gel/jelly products
Most studies used MCT oil or gel formulations.
The range of MCT doses used in clinical studies is quite wide.
The daily intake ranges from 2 grams to 80 grams .
Muscle mass and strength (sarcopenia and weakness)
aldult :
Studies have shown that for adults who have or are at risk of developing sarcopenia and weakness, daily oral administration of a combined dose of 6 grams of octanoic acid and decanoic acid for 12 weeks can improve muscle strength and function.
Special Notes :
- The number of relevant studies is extremely small.
- Lack of dose-response and time-course studies
- It is unclear whether other dosages or supplementation periods are equally effective.
- It is also unclear whether single MCT and mixed MCT have the same effect on this result.
Improved cognitive function
aldult :
For adults without known health problems, studies have shown that daily oral administration of a combined dose of 6 to 40 grams of caprylic acid and capric acid for 2 weeks to 6 months can improve cognitive performance (including working memory and executive function).
Another study indicated that a single intake of 20 grams of caprylic acid and capric acid may also produce positive effects.
Special Notes :
- A meta-regression has not yet been performed, therefore the optimal dosage and timing of supplementation remain undetermined.
- It's unclear which MCT is most effective, or whether the combination of caprylic and capric acid is the most ideal.
- Many studies were funded and written by MCT product manufacturers, presenting a significant conflict of interest.
Fat oxidation
aldult :
Studies have shown that daily oral administration of a combined dose of 2 to 6 grams of caprylic acid and capric acid for 2 weeks can increase the rate of fat oxidation during a high-fat diet and low-intensity exercise.
Special Notes :
- The number of relevant studies is extremely small.
- The study participants were limited to men without known health problems.
- Most studies compare MCTs with carbohydrates or a placebo with no calories, rather than with other fats.
- The effects are not necessarily unique to MCT.
- Lack of dose-response and time-course studies
- It is unclear whether a single MCT will have the same effect.
Weight loss and maintenance
aldult :
In the study, the MCT dosage ranged from 4 to 54 grams per day for weight loss, with a supplementation period of 4 to 16 weeks .
Special Notes :
- Many studies were funded and written by MCT product manufacturers, presenting a clear conflict of interest.
- The impact on body weight is generally small, and the research results vary considerably.
- It is unclear which MCT is most effective, or whether a combination of them is better.
It is currently unclear whether MCT should be taken with food .
Due to insufficient comparative studies on the effects of "having eaten" versus "fasting", relevant conclusions have not yet been established.
Not recommended to take with medium-chain triglycerides
MCT is absorbed rapidly, and taking large amounts on an empty stomach can easily cause diarrhea, abdominal pain, nausea, or heartburn .
Example : Drinking a large amount of MCT oil on an empty stomach in the morning.
Recommendation : Start with a small dose , taken with meals or in divided doses.
Consuming multiple high-fat foods at the same time may overburden the digestive system and cause fatty diarrhea.
Examples : Fish oil, evening primrose oil, flaxseed oil + MCT
Recommendation : Avoid taking large amounts of supplements at once; it's better to take them at different times or in separate meals.
MCT may affect energy metabolism and blood glucose stability, and in rare cases, it may cause hypoglycemia when used with medications.
Examples : Insulin, oral hypoglycemic agents
Recommendation : Avoid high doses and monitor blood glucose response.
It is recommended to start with 5 mL (1 teaspoon) per dose.
- Common dosage after tolerance is established: 10–15 mL/day
- Can be added to coffee, milkshakes, or served with meals.
Safety Information and Side Effects
- Medium-chain triglycerides are generally considered safe with a low risk of toxicity.
- Common side effects include gastrointestinal symptoms such as diarrhea, abdominal pain, and bloating.
- Breastfeeding mothers should be cautious when supplementing with nutritional products, as there is limited safety data, although the likelihood of harm appears to be low.
- Currently, there is a lack of research on the safety of ketone supplementation during pregnancy. Considering the potential risks of elevated ketone levels during pregnancy, it may be reasonable to avoid taking ketone supplements.
- No interaction between medium-chain triglycerides and drugs has been found so far.
Medium-chain triglycerides (MCTs) are generally considered safe and well-tolerated. Gastrointestinal upset, especially diarrhea, is the most common reported adverse reaction, and diarrhea appears to worsen with doses exceeding 20 grams. Animal studies have shown that MCTs pose extremely low risks of toxicity in reproduction, organ health, immune function, and cancer.
Currently, there is a lack of human data to confirm the safety of medium-chain triglyceride (MCT) intake during pregnancy. Animal studies have not found any risks. While the amount of MCT in food may be safe, the safety of MCT supplementation is unclear, and it may be advisable to avoid it until more research results are available.
Some studies suggest that elevated ketone body levels during pregnancy may be associated with adverse fetal reactions and impaired child development. However, further research is needed to confirm this and determine whether ketone bodies themselves cause these adverse reactions, and if so, whether medium-chain triglycerides (MCTs) can raise ketone body levels to a level sufficient to produce similar risks.
Medium-chain triglycerides (MCTs) are commonly used in infant formula to mimic the medium-chain fatty acids naturally present in breast milk. However, there is currently a lack of human data to confirm the safety of MCT supplementation in breastfeeding women. While harm appears unlikely, and animal studies have not found any adverse effects, caution is still advised until more research results are available.
Medium-chain acetyl-CoA dehydrogenase deficiency
Medium-chain acetylglucosamine dehydrogenase deficiency (MCADD) is a rare genetic disorder that prevents the body from properly breaking down medium-chain fatty acids for energy. This can negatively impact health during periods of high metabolic demand (such as exercise) or when carbohydrate intake is insufficient. It is recommended that individuals with MCADD avoid or minimize their intake of medium-chain triglycerides.
