The role of technology in the past and future development of the doubly labelled water method

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The doubly labelled water method is an isotope-based technique that is used to measure the energy demands of free-living animals and humans. It is based on the observation that, in the body, the oxygen in carbon dioxide is in complete isotope exchange equilibrium with the oxygen in body water. Hence, a label of isotopic oxygen in body water is eliminated by both respiratory CO2 and water turnover, whereas a similarly introduced label of deuterium is eliminated only by water flux. The difference in isotope fluxes therefore permits estimation of CO2 production, which is correlated to energy demands. The doubly labelled water method has been advanced predominantly by technological advances in mass spectrometry. Although it was first described in the 1950s, it was only used on small animals and in low numbers because the costs of the isotopes were a primary constraint. However, advances in mass spectrometry precision and accuracy in the 1980s made it possible to reduce the quantities of isotope used, and hence apply the method on humans, although still in small numbers. The advent of continuous flow inlets in the 1990s made possible the processing of samples in much larger numbers and the sample sizes of studies have expanded. Ironically, however, the technique is now under treat because of technological advances in another area (positron emission tomography), which has generated an enormous demand for O-18 and pushed up the price of isotopes. A continuation of this trend might drive prices to levels where sustained application of the method in human studies is questionable. Replacing determination of isotope enrichments currently performed by isotope ratio mass spectrometry with determinations made by stable isotope infrared laser spectrometry may be a technological advance that will get us out of this problem.

Original languageEnglish
Pages (from-to)335-343
Number of pages9
JournalIsotopes in Environmental and Health Studies
Volume41
DOIs
Publication statusPublished - 2005

Keywords

  • doubly labelled water method
  • energy expenditure
  • hydrogen-2
  • IR spectrometry
  • isotope analysis
  • oxygen-17
  • oxygen-18
  • RATIO MASS-SPECTROMETRY
  • LASER SPECTROMETRY
  • ENERGY-EXPENDITURE
  • SMALL MAMMALS
  • ABUNDANCE
  • PRECISION
  • HYDROGEN
  • COSTS

Cite this