What is MCT?
Medium chain triglycerides (MCTs) are a class of lipids in which three saturated fats are bound to a glycerol backbone. What distinguishes MCTs from other triglycerides is the fact that each fat molecule is between six and twelve carbons in length. MCTs are a component of many foods, with coconut and palm oils being the dietary sources with the highest concentration of MCTs. MCTs are also available as a dietary supplement.
Difference Between LCT & MCT:
MCTs have a different pattern of absorption and utilization than long-chain triglycerides (LCTs) that make up 97 percent of dietary fats. For absorption of LCTs to occur, the fatty acid chains must be separated from the glycerol backbone by the lipase enzyme.
These fatty acids form micelles, are then absorbed and reattached to glycerol, and the resultant triglycerides travel through the lymphatics en route to the bloodstream. Up to 30 percent of MCTs are absorbed intact across the intestinal barrier and directly enter the portal vein. This allows for much quicker absorption and utilization of MCTs compared to LCTs.
MCTs are transported into the mitochondria independent of the carnitine shuttle, which is necessary for LCT-mitochondrial absorption. Oxidation of MCTs provides 8.3 calories per gram. For more information on the absorption and utilization of MCTs, consult Ruppin and Middleton.
The use of MCTs is clearly indicated in malabsorption states. Children with cystic fibrosis supplemented with up to 75 mL of MCTs per day experienced greater weight gain and reduced fecal fat compared to a trial period on a control diet. When MCTs are given concurrently with a pancreatic enzyme preparation, absorption is improved. MCTs have been used in other malabsorption syndromes, including short-bowel syndrome, celiac disease, and hepatic disease.
In chronically ill patients receiving total parenteral nutrition, preparations containing 50 percent of fat calories from MCTs led to a significantly lower production of tumor necrosis factor-alpha (TNF[alpha]) compared to a solution with 100 percent LCTs. TNF[alpha] is a cytokine thought to be responsible for at least some symptoms of cachexia.
MCTs have been used as part of a ketogenic diet to treat children with intractable seizures and cancer. The ketogenic diet varies, but generally contains 60 percent of calories from MCT oil, 20 percent from protein, 10 percent from carbohydrate, and 10 percent from other dietary fats.
Although some preliminary data are available showing reduced sugar metabolism at tumor sites, use of ketogenic diets to treat active cancers remains unproven. A small study showed an enteral formula containing MCTs and hydrolyzed casein protein led to better weight maintenance during radiation therapy than an ad libitum diet.
Weight Loss Programs:
In a randomized, crossover trial, 12 non-obese women fed a diet providing 80 percent of fat calories as MCTs (40% of total calories from fat) exhibited a greater rate of oxidation of long-chain saturated fats for energy. Another study demonstrated an increased metabolic rate in response to substitution of just 20 percent of fat calories with MCTs.
Obese women fed an 800 kcal/ day diet with 24 percent of calories from MCTs had no more weight loss than women eating a similar diet without MCTs. While some authors have theorized a role for MCTs in weight control, this role has yet to be fully defined.
It has been theorized that MCTs improve energy utilization during exercise, but this has not been conclusively demonstrated in clinical trials. One study found similar exercise performance among subjects fed 400 kcal as MCTs, LCTs, or carbohydrates.
Subjects used MCTs as an energy source more efficiently than LCTs, but less efficiently than carbohydrates. Another clinical trial found cyclists ingesting a five-percent MCT solution actually had decreased exercise performance compared to those taking a carbohydrate solution or placebo. This decrease in exercise performance was thought to be due to gastrointestinal upset. When MCTs were given concurrently with carbohydrate, no negative effect on performance was noted.
In the inpatient setting, an experimental diet containing 78 percent of fat calories as MCTs (31% of total energy intake) increased glucose metabolism in patients with type 2 diabetes mellitus. In five outpatients with type 2 diabetes, an experimental diet containing 18 percent of calories from MCTs led to a slight reduction in postprandial blood sugar and no effect on fasting blood sugar. The role of MCTs in the management of diabetes remains to be decided.
3. Who needs them and what are some symptoms of deficiency?
Although there are no symptoms of deficiency, everyone may benefit from supplementing with medium chain triglycerides.
Often, people will consume foods that are high in saturated fat. Simply because of this, medium chain triglyceride oil is a healthy, natural, alternative. Populations that may benefit from medium chain triglyceride supplementation include: endurance athletes11, ectomorphs and more.
People trying to lose weight may find MCT consumption helpful toward the goal of weight loss. Fat molecules are calorically dense, and consumption of healthy fats (as a substitute for bad fats) will lead to a feeling of satiation and fullness. Consumption of good fats will allow one to reduce food cravings, feel a sense of fullness, and avoid the accumulation of body fat that is associated with the consumption of bad fats.
Because MCT's are used by the body as a direct source of energy, endurance athletes may find them to be a preferable and long-lasting energy source when undergoing physical exercise.
Hardgainers may find medium chain triglyceride supplementation to be helpful in the quest to gain mass, without the side effects associated with consuming other fat molecules (fat storage). They will effectively provide the hardgainer with the means to increase caloric intake, without adding body fat.
4. Are there any side effects? How much should be taken?
The only noted side effect of MCT consumption occurs when MCT's are taken on an empty stomach, and if in great quantities. Irritation can occur under these circumstances.
Research has established that MCT's are safe for human consumption. Still, individual tolerance will vary. Individuals with gastrointestinal issues should avoid the use of MCT's. Diabetics should consult with a qualified medical practitioner prior to the use of MCT's. Dosage guidelines have not yet been established, so it is best to follow label directions.
5. Where can I get it?
There are different brand names that manufacture supplemental MCT.
Provide a quick source of energy
Help mobilize body fat stores for energy
Increase the metabolic rate
Spare lean body mass (muscle)
Widely available in drugstores and health food stores
MCT oils have a long history of safety.
Ultimate Nutrition's MCT Gold
Health Support's Coconut Oil