Metabolic availability of oral medium chain triglycerides co
-ingested with carbohydrates during prolonged exercise .
Jeukendrup, Asker E, Wim H M Saris, Patrick Schrauwen, Fred Brouns,
Anton J M Wagenmakers.
Department of Human Biology, Nutrition Research Centre, University
of Limburg, Maastricht, The Netherlands
APStracts 2:0160A, 1995.
The present study examined the metabolic response to medium chain
triglycerides (MCT) ingestion with or without carbohydrates (CHO).
Eight well-trained athletes cycled 4 times 180 min at 50% Wmax (57%
VO2max). Subjects drank a bolus of 4 ml.kg-1 at the start and 2
ml.kg-1 every 20 min during exercise of either a 15% (214 g) CHO
solution (CHO), an equicaloric 149 g CHO + 29 g MCT suspension
(CHO+MCT), 214 g CHO + 29 g MCT (HCHO+MCT) or 29 g MCT (MCT).
Exogenous MCT oxidation was measured by adding a [1,1,1-13C]-
trioctanoate tracer to the MCT oil. 13CO2-enrichment of breath
samples was measured every 15 min. During the second hour (60 - 120
min period) the amount of MCT oxidized was 72% of the amount ingested
with CHO+MCT whereas during the MCT trial only 33% was oxidized. The
rate of MCT oxidation increased more rapidly during both CHO+MCT
trials compared to MCT, yet in all three cases the oxidation rate
stabilized at 0.12 g.min-1 during 120-180 min of exercise. It is
concluded that more MCT is oxidized when ingested in combination with
CHO. Data do confirm the hypothesis that oral MCT might serve as an
energy source in addition to glucose during exercise since the
metabolic availability of MCT was high during the last hour of
exercise with oxidation rates being about 70% of the ingestion rate.
However, the maximal amount of oral MCT that can be tolerated in the
gastrointestinal tract is small (about 30 g) and limits the
contribution of oral MCT to total energy expenditure to values
between 3 and 7%.
Received 15 February 1995; accepted in final form 13 April 1995.
APS Manuscript Number A186-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.