Medium-chain triglycerides (MCTs) are a naturally occurring source of dietary fats that are abundant in coconut oil. Our bodies rapidly convert MCTs into ketones, which can be used as an energy source by the brain. No studies have yet found that MCTs can prevent dementia, but some evidence suggests that there may be short-term cognitive benefits from taking MCTs, including for patients with dementia. While they are generally considered safe, some gastrointestinal side effects are common.
More than a dozen trials have investigated the cognitive impacts of MCTs in different populations, and four systematic reviews and/or meta-analyses have assessed these clinical trials. The analysis is hampered by several methodological issues, including suboptimal study design, small study size, and widely varying doses and kinds of MCTs. Our search identified:
In healthy individuals, glucose supplies almost all of the brain’s energy. However, in certain patient populations (e.g. those with or developing Alzheimer’s disease, type 2 diabetics) the ability of the brain to use glucose is impaired. Ketones are an alternative energy source for the brain and might be able to compensate for this impairment [1; 2].
Several clinical trials have tested MCTs in patients with and without dementia and reported benefits. Some meta-analyses and systematic reviews of these studies overall suggest potential cognitive benefits of MCT usage [3; 4; 5], though not all do [6]. However, many of the studies had design issues. For instance, some studies were small, or did not compare MCT to a placebo, or were not blinded – that is, the participants knew they were receiving MCTs – which means results could be biased. Studies also used very different kinds and doses of MCTs. Some of the studies found no benefit of MCTs, including one Phase 3 study [7]. Overall, the evidence suggests that MCTs might have benefits, but larger and better controlled studies are needed to determine whether these benefits are real. It is also not known what the effects are of taking MCTs long term, as no identified trial lasted longer than six months [8]. No human studies have examined whether MCTs can prevent or delay dementia.
Although some laboratory studies provide a biological rationale of how MCTs might benefit brain health such as improving brain cell function, preventing Alzheimer's-like pathology, and enhancing learning in older animals [9; 10; 11], there exists no clinical data that MCTs promote long-term brain health.
Studies suggest that MCT supplementation might improve cognitive function only in, or to a greater extent in, patients who do not have an APOE4 allele [5].
For more information on what the APOE4 gene allele means for your health, read our APOE4 information page.
Potential cognitive benefits for patients with dementia have been reported, though larger and longer studies looking specifically at individuals with dementia are needed [3; 5]. Some preclinical laboratory studies suggest that MCTs may improve some measures of cognition and prevent amyloid plaque formation in animals, but these results have not been confirmed in humans [10; 11; 12].
Strong evidence suggests that MCTs are low risk when used by healthy adults. Foods high in MCTs such as coconut oil are used widely with few adverse events reported. However, for some people MCTs can increase plasma triglyceride levels, which might be harmful for cardiovascular health [8; 13; 14]. Gastrointestinal side effects are common in individuals taking MCTs. The side effects may be reduced by taking MCTs with food and by slowly incorporating them into the diet.
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.
MCTs can be found in certain foods, as supplements, and as medical foods. Coconut oil has the highest naturally occurring percentage of MCTs, which make up nearly 60 percent of its total fat content. Coconut oil has other fats as well as MCTs, so some individuals opt for refined versions of coconut oil or MCT oil that have higher proportions of MCTs. Palm oil and butter also contain significant amounts of MCTs. In most studies, individuals have taken 6-56 g of MCTs per day.
Full scientific report (PDF) on Cognitive Vitality Reports
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