Author and graduation date: Natalie LAGOMARCINO, December, 1999

Committee members: Mark Kern (Chair), Michael Buono, Michael Dowler

Thesis title: The Effects of Medium Chain Triglycerides on the Blood Lipid Profiles of Male Endurance Runners

This study assessed the effects of short-term consumption of medium-chain triglycerides (MCT) on the blood lipid profiles of male endurance runners. MCT oil is currently marketed for athletes as an ergogenic aid for optimal performance. Previous animal studies have indicated that MCT decreases serum cholesterol concentration, but elevates triglyceride concentration. Research on humans regarding the short-tem-i consumption of MCT on blood lipid concentrations is very limited and inconclusive. Additionally, the research investigating the effects of acute exercise on blood lipids in exercisers is contradictory. In this study, subjects consumed approximately 60 g/day of supplemental MCT or LCT oil (corn oil) for 14 days. At the end of each dietary period, maximal and submaximal exercise tests separated by 30 minutes were administered. Fasting blood samples were drawn prior to the maximal test and after 45 minutes of submaximal exercise (30 min: 85%, 15 min: 75% VO2max) and were analyzed for serum concentrations of total cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), and triglycerides (TG). Comparisons for biochemical data were performed using 2 x 2 repeated measures ANOVA. Concentrations of TC (147.8 + 4.6 vs. 131.7 + 5.8 mg/dl, p = 0.001), LDL-C (08.0 + 4.5 vs. 58.3 + 5.5 mg/dl, p = 0.012), and TG (112.3 + 12.7 vs. 86.5 + 11.0 mg/dl, p = 0.006) were higher following the MCT diet period in comparison to the LCT trial, respectively. HDL-C concentration did not differ significantly between diet trials (MCT = 57.3 + 2.1 vs. LCT = 56.1 + 1.4 mg/dl, p = 0.824). No main effects of exercise on blood lipids were detected. Although blood lipids remained within normal ranges, these results suggest that consumption of MCT oil for two weeks negatively alters the blood lipid profiles of athletes. Further studies should be conducted to determine the effects of longer periods of MCT supplementation on serum lipids of exercisers. Other populations should also be considered to further examine the effects of MCT supplementation. With little data suggesting that MCT are truly ergogenic, the adverse effects of MCT on blood lipid concentrations may outweigh any proposed benefits for athletes.

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