Effects of caffeine ingestion on norepinephrine kinetics, fat oxidation,
and energy expenditure in younger and older men.
Arciero, Paul J., Andrew W. Gardner, J. Calles-Escandon, Neil L. Benowitz &
Eric T. Poehlman.
Department of Medicine, Division of Gerontology, University of Maryland,
Baltimore VA Medical Center, Baltimore, MD 21201, Department of Physical
Education, Skidmore College, Saratoga Springs, NY, 12866, Department of
Medicine, University of Vermont, Burlington, VT, 05405 and Division of
Clinical Pharmacology and Experimental Therapeutics, University of
California, San Francisco, CA, 94110
APStracts 2:0006E, 1995.
Age-related differences in energy expenditure, fat oxidation, and
norepinephrine kinetics following caffeine ingestion were examined using a
placebo-controlled, double-blind study in 10 older (O)(65-80 yr) and 10
younger (Y)(19-26 yr) men who were moderate consumers of caffeine. Caffeine
ingestion resulted in similar increases in Y and O men for plasma caffeine
levels (Y=89 +/- 100 to 6340 +/- 1938 ng.ml-1, P<0.05: O=124 +/- 38 to 7066
+/- 2366 ng.ml-1, P<0.05) and energy expenditure (Y=11%; 1.38 +/- 0.15 to 1.52
+/- 0.22 kcal.min-1, P<0.05: O=9.5%; 1.15 +/- 0.13 to 1.26 +/- 0.20 kcal.min-
1, P<0.05). However, caffeine ingestion increased fatty acid concentrations
(362 +/- 159 to 803 +/- 253 Nmoles.L1, P<0.05) and tended to increase rate of
appearance (Ra) of fatty acids (624 +/- 376 to 1394 +/- 1331 Nmoles.L-1,
P=0.07) in younger but not older men. Rates of fat oxidation, and
norepinephrine appearance and clearance did not significantly differ from
baseline values in either group. In conclusion, older and younger men show a
similar thermogenic response to caffeine ingestion, whereas older men show a
smaller increase in fatty acid availability following a caffeine challenge.
These metabolic differences are not related to alterations in norepinephrine
kinetics or fat oxidation.
Received 14 July 1994; accepted in final form 12 January 1995.
APS Manuscript Number E269-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.