Background Information
Medium chain triglycerides (MCT) are derived from coconut oil and palm kernel oil and contain medium chain fatty acids which are more rapidly hydrolyzed absorbed and metabolized than ordinary long chain triglycerides (LCT). Since MCTs are absorbed into the blood as medium chain fatty acids and metabolized as quickly as glucose it has been hypothesized that they might provide an alternate carbon source for muscle metabolism during prolonged exercise and spare muscle glycogen.

 Effects on Performance
Studies have examined the oxidation of MCTs during prolonged exercise and reported no effect on total rates of carbohydrate and fat oxidation during exercise or on the rate of muscle glycogen hydrolysis. This is probably due to the small amount of MCT ingested (25-39 g) in these studies. MCTs are highly unpalatable and typically cause gastrointestinal cramping and diarrhea when taken in amounts greater than 30 g. Therefore, one of the difficulties in studying the effects of MCT is finding a way to make large concentrations tolerable.

The effect of providing MCT during exercise on exercise metabolism has also been investigated. Studies have shown when MCTs are ingested with carbohydrate during exercise, they are more rapidly oxidized than when ingested alone. However, the contribution of MCT to total energy expenditure was only 3-7% and there was no significant difference in substrate oxidation during exercise.

Performance during moderate intensity exercise is also unaffected by MCT consumption. Researchers found no difference in time to exhaustion at 60% VO2 max one hour after ingestion of isocaloric amounts of either carbohydrate, MCT or a fast, although the respiratory exchange ratio tended to be lowest following the ingestion of the MCT.

 Recommendation
Consuming more than 30 g of MCTs may cause gastrointestinal problems. Ingestion of large amounts may stimulate ketone body formation