Adaptation of the doubly labeled water method for subjects
consuming isotopically enriched water.
Gretebeck, Randall J., Dale A. Schoeller, Rick A. Socki, Janis Davis
-Street, Everett K, Gibson, Leslie O. Schulz, and Helen W. Lane.
Nutritional Biochemistry and 3Stable Isotope Laboratories, Space
and Life Sciences Directorate, NASA/Johnson Space Center, Houston,
TX, The Committee on Human Nutrition and Nutritional Biology,
University of Chicago, Department of Medicine, Chicago, IL and Health
Sciences, University of Wisconsin, Milwaukee, Milwaukee, WI
APStracts 3:0419A, 1996.
The use of doubly labeled water (DLW) to measure energy expenditure is
subject to error if the background abundance of the oxygen and
hydrogen isotope tracers changes during the test period. This study
evaluated the accuracy and precision of different methods by which
such background isotope changes can be corrected, including a
modified method that allows prediction of the baseline that would be
achieved if subjects were to consume water from a given source
indefinitely. Subjects in this study were 8 women (4 test subjects
and 4 control subjects) who consumed water enriched to resemble
drinking water aboard the U.S. Space Shuttle for 28 days. Test
subjects and control subjects were given a DLW dose on days 1 and 15
respectively. The change to an enriched water source produced a bias
in expenditure calculations that exceeded 2.9 MJ/d (35%) relative to
calculations from intake/balance. The proposed correction based on
the predicted final abundance of 18O and deuterium after
equilibration to the new water source eliminated this bias, as did
the traditional use of a control group. This new modified correction
method is advantageous under field conditions when subject numbers
are limited.
Received 20 May 1996; accepted in final form 26 August 1996.
APS Manuscript Number A470-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996