The effect of medium-chain triacylglycerols on the blood lipid profile of male endurance runners

Medium-chain triacylglycerol (MCT) oil is currently marketed for athletes a s an ergogenic is very limited and inconclusive. In the randomised cross-ov er study, male endurance runners (aged 30.5 +/- 5.5 years) were instructed to consume a lo-fat diet (approximately 15% of energy) and consume either s upplemented MCT oil (3- g twice each day) or long-chain triaclglycerol (LCT ) oil (28 g corn oil twice each day) for 14 days. Each dietary trial was se parated by at least 3 weeks. At the end of each trial, fasting blood sample s were collected and analyzed for serum concentrations of total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotei n-cholesterol (LDL-C), and triacylglycerol (TG). Concentrations of TC (3.83 +/- 0.12 vs. 3.41 +/- 0.15 mmol/L, P = 0.004), LDL-C (1.76 +/- 0.12 vs. 1. 51 +/- 0.14 mmol/L, P = 0.033), and TG (1.26 +/- 0.14 vs. 0.98 +/- 0.12 mmo l/L, P = 0.006) were higher following the MCT trial than following the LCT trial, respectively. HDL-C concentration did not differ significantly betwe en trials (MCT 1.48 +/- 0.05 mmol/L vs. LCT 1.45 +/- 0.04 mmol/L, P = 0.465 ). Although blood lipids remained within desirable ranges established by th e National Cholesterol Education Program, these results suggest that consum ption of MCT oil for 2 weeks negatively alters the blood lipid profile of a thletes. Future studies should determine the effects of longer periods of M CT supplementation on serum lipids of exercisers and other groups of indivi duals. With little data suggesting that MCT are ergogenic, the adverse effe cts of MCT on blood lipid concentration may outweigh any proposed benefits for athletes. (C) Elsevier Science Inc, 2000. All rights reserved.