Medium-chain triglycerides (MCTs) are a naturally occurring source of dietary fats that are abundant in coconut oil. Our bodies rapidly convert them 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 patients with dementia might find short-term benefit using MCTs. While they are generally considered safe, some gastrointestinal side effects are common.
Only two small clinical trials have studied the impact of MCTs on cognition. They were in different patient populations and reported contradictory results.
• Two randomized controlled trials, one in elderly individuals with age-related cognitive decline and one in diabetic patients
• 0 observation studies
• Multiple preclinical studies
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 II 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 .
One clinical trial in elderly individuals with age-related cognitive decline reported no cognitive improvement with an MCT supplement (here). However, another small clinical trial in diabetic patients reported that MCT supplements preserved cognitive function in conditions of artificial hypoglycemia (where glucose levels were held low) . 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 , there exists no clinical data that MCTs promote long-term brain health.
Two clinical trials reported that MCT supplements improved cognitive function in mild cognitive impairment (MCI) and Alzheimer's disease patients who do not carry the APOE4 genotype but were ineffective for APOE4 carriers . For more information on what the APOE4 gene allele means for your health, read our APOE4 information page.
Two clinical trials suggest that an MCT supplement (Axona®) may provide an acute benefit in patients with MCI and Alzheimer's disease. However, these improvements were short-lived and disappeared 14 days after the supplement was stopped . Both trials were funded by Accera, the company that sells Axona®. No studies have tested the effects of MCTs in patients with severe dementia. 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 .
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. For some people, though, MCTs can increase plasma triglyceride levels, which might be harmful for cardiovascular health . And mild 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. Palm oil and butter also contain significant amounts of MCTs. In most studies, individuals have taken 10-40g of MCTs per day.
Additional information on MCTs is available at WebMD.