Rates of free fatty acid appearance and fat oxidation in healthy
younger and older men .
Toth, Michael J., Paul J. Arciero, Andrew W. Gardner, Jorge Calles
-Escandon, and Eric T. Poehlman.
Division of Gerontology, Department of Medicine, University of
Maryland, Baltimore, MD 21201, Gerontology Research Education and
Clinical Center, Baltimore VA Medical Center; Department of Medicine,
University of Vermont, Burlington, Vermont 05405
APStracts 2:0436A, 1995.
Alterations in the mobilization and oxidation of fat may partially
account for age-related alterations in body composition. To
investigate age-related alterations in fat metabolism, we compared
basal rate of appearance of free fatty acid (RaFFA) and total body
fat oxidation, as measured by infusions of 14C palmitate and indirect
calorimetry, respectively, in eighteenunger (23 +/- 1 yrs) and 30
older (69 +/- 1 yrs) men. We also examined whether age-related
differences in body composition, body fat distribution, peak oxygen
consumption (peak VO2), dietary intake and/or fasting insulin levels
may explain age-related variation in RaFFA and total body fat
oxidation. The RaFFA showed a tendency to be higher in older compared
to younger men (1134 +/- 184 vs 680 +/- 105 [mu]mol min-1, P=0.07),
whereas total body fat oxidation was similar between groups (younger:
257 +/- 25 vs older: 222 +/- 9 [mu]mol min-1). The estimated rate of
non-oxidative disposal of free fatty acids showed a tendency to be
higher in the older (913 +/- 182) than younger men (423 +/- 103
[mu]mol min-1; P=0.06). Fat-free mass was the most significant
predictor of RaFFA in younger (r=0.63; P<0.01) and older
(r=0.41; P<0.05) men. These results suggest that older men
recruit fatty acids from adipose tissue stores in excess of the
energy needs of respiring tissue. However, variation in RaFFA between
the age groups could not be explained by differences in body habitus
or fasting insulin levels.
Received 17 April 1995; accepted in final form 18 September 1995.
APS Manuscript Number A414-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95