Medium chain triglycerides (MCTs) are a naturally occurring source of dietary fat and are abundant in coconut oil. MCT supplements may briefly improve brain function in people with mild to moderate cognitive impairment by providing an additional energy source for the brain. However, the clinical evidence is limited to small patient populations treated for short amounts of time. These supplements are considered generally safe for healthy people although gastrointestinal side-effects can occur.
Medium chain triglycerides (MCTs) are source of dietary fat naturally found in certain animal and vegetable oils and are abundant in coconut oil. They are often given to patients with malabsorption disorders because they are easily tolerated and more readily digested than other forms of fat.
Did you know? The word "coconut" comes from 15th century explorer Vasco da Gama and his crew, who thought the fruit looked like the face of Coco, a mythical creature from Portuguese folklore!
There are several sources of medium chain triglycerides.
• Food: MCTs are naturally found in foods such as coconut oil, palm oil, and butter. Coconut oil has the highest naturally occurring percentage of MCTs, which compose nearly 60% of its total fat content.
• Supplements: MCT supplements are available over the counter and marketed as weight loss aids or athletic performance enhancers due to their ability to be rapidly absorbed by the body and turned into energy. The evidence to support the efficacy of MCT supplements for weight loss or athletic endurance has been controversial [2-4]. These supplements will often differ in composition and quality.
One particular supplement, Axona® (AC-1202) is marketed to possibly alleviate symptoms in patients with mild-to-moderate Alzheimer's disease. It is an MCT with glycerin and caprylic acid. In a double-blind randomized clinical trial paid for by the manufacturers, Axona® prevented cognitive decline over 3 months in Alzheimer’s patients, particularly patients who lack the APOE4 genetic risk factor . Further studies are needed to confirm these results and determine the effects of long-term Axona® treatment of this chronic disease.
Despite being labeled a “medical food” on their website, Axona® has not been granted this status by the FDA. The FDA defines a “medical food” as a supplement used to help meet basic nutritional requirements in patients with malnutrition and malabsorption disorders. Because Alzheimer’s disease is not a condition proven to have specific dietary needs, Axona® is not considered a medical food.
• Medical foods: Certain MCT formulas, including MCTprocal and MCT Oil®, are approved as medical foods for specific severe malnutrition or digestive disorders. Medical foods can only be obtained by prescription.
Possibly, based on very limited evidence.
In animals, MCTs supplementation can improve brain cell function, reduce Alzheimer’s-like pathology, and enhance learning in older animals [9,10]. No human studies have examined if MCT supplementation can prevent or delay dementia. However, one clinical trial is currently recruiting volunteers to study how MCTs may affect ketone body production and cognitive function in healthy adults (NCT01702480). Theoretically, the brain’s ability to use glucose becomes impaired many years before a person is diagnosed with Alzheimer’s disease. In these people, MCTs might slow the onset of the disease but this idea remains untested.
Possibly, based on moderate evidence.
In two small clinical trials, MCT treatment improved cognitive function in some patients with mild to moderate Alzheimer’s disease over 90 days  or in people with mild cognitive impairment or probable AD (one dose) . However, almost half of the patients experienced gastrointestinal side effects  and the memory benefit was seen only in patients who lack the APOE4 genetic risk factor [1,11]. In other words, MCT treatment may eventually be the right choice for some people, but definitely not everyone. Both of these trials were paid for by Accera, the company that sells Axona®. No studies have tested the effects in patients with severe dementia. Longer-term clinical trials with larger patient populations are underway to test the effect of treatment for longer than 90 days.
Unknown, given there is no evidence.
MCTs are often marketed as weight loss aids or to enhance athletic performance due to their ability to be rapidly absorbed by the body and turned into energy. However, controlled clinical trials were unable to demonstrate that MCT supplements can decrease body mass [2,4], nor were they able to demonstrate any performance enhancing effects that counter age-related physical decline .
The brain’s main source of energy comes from the sugar, glucose. However, in patients with mild cognitive impairment or dementia, brain cells lose some of their ability to use glucose as a fuel. This effect may accelerate disease progression, worsen cognitive abilities [5,6] and increase Alzheimer’s disease pathology [7,8]. MCTs may provide a substitute for glucose: once ingested, they are broken down by the liver into ketone bodies, which are then released into the bloodstream to provide an alternate source of fuel for the body and brain.
In animals, MCTs supplementation can improve brain cell function, reduce Alzheimer’s-like pathology, and enhance learning in older animals [9,10]. Additionally, preliminary clinical trials in patients with mild to moderate cognitive impairment suggest that taking MCT supplements may alleviate some memory and attention deficits [1,9,11].
Probably safe, based on strong evidence.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Strong evidence suggests that MCTs are safe when properly used by healthy adults, although there is little evidence about their safety for long-term use. Although MCTs are considered generally safe, they should not comprise more than 50% of total dietary fat calories because it is important to maintain a balanced fat intake .
MCTs are well-tolerated by most people at oral doses of 20 to 40 grams per day. However, gastrointestinal side effects are common. For example, Axona® caused gastrointestinal side effects in 50% of Alzheimer’s patients in a clinical trial . The side effects can sometimes be reduced by taking them with food and by slowly incorporating MCTs into the diet, rather than starting at a high dose. Patients with liver disease should not take MCT supplements because MCTs and ketones are metabolized by the liver.
It is important to consult with a physician before beginning an MCT supplement regimen to be sure that they are right for you and that they will not interfere with other drugs and treatments and to ensure you maintain healthy cholesterol and triglyceride levels while taking MCT supplements. Even though some MCT blends are sold over-the-counter, the MCT formulation Axona® is only available by prescription.
Several ongoing clinical trials are testing the long-term effects of MCT dietary supplements, including their effects on brain health (NCT01122329) and overall patient health (NCT01538212) in people with Alzheimer’s disease and mild cognitive impairment. One trial is also underway to examine the effect of MCTs on cognitive function in healthy adults (NCT01702480). A trial currently recruiting at University of South Florida is studying coconut oil (which contains a high percentage of MCTs) as a treatment for Alzheimer's disease (NCT01883648). Additionally, participants are being recruited for clinical trials to study MCTs as a treatment for multiple sclerosis (NCT01848327) and type I diabetes (NCT01315171). More information about these and other trials can be found at clinicaltrials.gov (U.S.) and at clinicaltrialsregister.eu (Europe).
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