Medium Chain Triglycerides

Also indexed as: MCT

What do they do? Medium chain triglycerides (MCT) are a class of fatty acids. Their chemical composition is of a shorter length than the long-chain fatty acids present in most other fats and oils, which accounts for their name. They are also different from other fats in that they have a slightly lower calorie content1 and they are more rapidly absorbed and burned as energy, resembling carbohydrate more than fat.2

MCT have been shown to increase calorie burning compared with other fats.3 4 However, researchers estimate that half of the calories in the diet would have to be eaten as MCT for significant weight loss to occur.5 Obese women on a calorie-restricted diet using MCT for 24% of total calories, experienced no greater weight loss after three months, than when regular fat was used.6 Whether MCT would help people lose weight on a normal diet has not been adequately studied.

Since MCT is more rapidly used for energy than other fats, some athletes have been interested in its use, especially during prolonged endurance exercise.7 However, no effect on carbohydrate sparing or endurance exercise performance has been shown, with moderate amounts of MCT (30–45 grams).8 9 Trials using very large amounts (about 85 grams) have produced conflicting results. One study found increased performance when MCT was added to a 10% carbohydrate solution,10 and another study actually reported decreased performance, probably due to gastrointestinal distress, in athletes using MCT.11

Because some short-term studies have shown that MCT lowers blood glucose levels, a group of researchers investigated the use of MCT to treat people with type 2 (non-insulin-dependent) diabetes mellitus.12 In nonhospitalized people with diabetes who consumed MCT for an average of 17.5% of their total calorie intake for 30 days, MCT did not improve diabetic control by most measures.13

Where are they found? Medium chain triglycerides are found in coconut oil, palm kernel oil, and butter. MCT are also available as a supplement.

Medium chain triglycerides have been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
1Star Athletic performance
Diabetes
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? Most people consume adequate amounts of fat in their diets and many people consume excessive amounts, so extra fat intake as medium chain triglycerides is unnecessary.

How much is usually taken? The best amount of medium chain triglycerides to take is currently unknown. Athletes are not likely to benefit from less than 50 grams during exercise. Larger amounts may possibly help some, but may also impair performance if not combined with carbohydrate.

Are there any side effects or interactions? Consuming medium chain triglycerides on an empty stomach can lead to gastrointestinal upset. Anyone with cirrhosis or other liver problems should check with a doctor before using MCT. Two reports suggest that MCT may raise serum cholesterol and/or triglycerides.14 15 MCT is actually the preferred fatty acid source for cirrhotic patients, but only when used intermittently.16

At the time of writing, there were no well-known drug interactions with medium chain triglycerides.

References:

1. Bach AC, Ingenbleek Y, Frey A. The usefulness of dietary medium-chain triglycerides in body weight control: fact or fancy? J Lipid Res 1996;37:708–26.

2. Bach AC, Babayan VK. Medium-chain triglycerides—an update. Am J Clin Nutr 1982;36:950–62.

3. Scalfi L, Coltorti A, Contaldo F. Postprandial thermogenesis in lean and obese subjects after meals supplemented with medium-chain and long-chain triglycerides. Am J Clin Nutr 1991;53:1130–3.

4. Seaton TB, Welle SL, Warenko MK, et al. Thermic effect of medium-chain and long-chain triglycerides in man. Am J Clin Nutr 1986;44:630–4.

5. Bach AC, Ingenbleek Y, Frey A. The usefulness of dietary medium-chain triglycerides in body weight control: fact or fancy? J Lipid Res 1996;37:708–26.

6. Yost TJ, Eckel RH. Hypocaloric feeding in obese women: metabolic effects of medium-chain triglyceride substitution. Am J Clin Nutr 1989;49:326–30.

7. Jeukendrup AE, Saris WH, Schrauwen P, et al. Metabolic availability of medium-chain triglycerides coingested with carbohydrates during prolonged exercise. J Appl Physiol 1995;79:756–62.

8. Jeukendrup AE, Wagenmakers AJM, Brouns F, et al. Effects of carbohydrate (CHO) and fat supplementation on CHO metabolism during prolonged exercise. Metabolism 1996;45:915–21.

9. Satabin P, Portero P, Defer G, et al. Metabolic and hormonal responses to lipid and carbohydrate diets during exercise in man. Med Sci Sports Exer 1987;19:218–23.

10. van Zyl CG, Lambert EV, Hawley JA, et al. Effects of medium-chain triglyceride ingestion on carbohydrate metabolism and cycling performance. J Appl Physiol 1996;80:2217–25.

11. Jeukendrup AE, Thielen JJHC, Wagenmakers AJM, et al. Effect of medium-chain triacylglycerol and carbohydrate ingestion during exercise on substrate utilization and subsequent cycling performance. Am J Clin Nutr 1998;67:397–404.

12. Eckel RH, Hanson AS, Chen AY, et al. Dietary substitution of medium-chain triglycerides improves insulin-mediated glucose metabolism in non-insulin dependent diabetics. Diabetes 1992;41:641–7.

13. Trudy J, Yost RN, Erskine JM, et al. Dietary substitution of medium-chain triglycerides in subjects with non-insulin dependent diabetes mellitus in an ambulatory setting: impact on glycemic control and insulin-mediated glucose metabolism. J Am Coll Nutr 1994;13:615–22.

14. Cater NB, Heller HJ, Denke MA. Comparison of the effects of medium-chain triacylglycerols, palm oil, and high oleic acid sunflower oil on plasma triacylglycerol fatty acids and lipid and lipoprotein concentrations in humans. Am J Clin Nutr 1997;65:41–5.

15. Hill JO, Peters JC, Swift LL, et al. Changes in blood lipids during six days of overfeeding with medium or long chain triglycerides. J Lipid Res 1990;31:407–16.

16. Fan ST. Review: nutritional support for patients with cirrhosis. J Gastroenterol Hepatol 1997;12:282–6.