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  • Letter to the Editor
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Reduction in O-18 dose – at what cost?

International Journal of Obesity volume 31, page 1033 (2007)Cite this article

We have read the recent paper by Mann et al.1 and wish to comment on the authors' statements. The authors claim that by using the most precise stable isotope techniques – that they have accomplished doubly labeled water analysis with one-tenth the standard dose – that is 0.02 g/kg body weight for H218O and 0.03 g/kg body weight for 2H2O is false. During the 1980s, we proposed a standard dose of 0.2 and 0.14 g of H218O and 2H2O per kilogram body water, respectively.2 Assuming that the average subject has about 50% of their weight as water, then the standard doses are 0.09 and 0.06 g H218O and 2H2O per kilogram body weight, respectively. Thus, the authors have only reduced the standard dose by factors of 5 and 2 for 18O and deuterium.

So what is the real cost of this reduced dose? The first cost is reduced precision in an individual estimate of energy expenditure.2, 3 Based on propagation of error analysis, the coefficient of variation on energy expenditure for the reduced dosage with multipoint analysis is 13.3%, compared to 4.1% for the standard dose using two-point analysis. We have demonstrated a precision of 5.1% for that standard dose, which is close to the one predicted; whereas these authors demonstrated a precision of 9.3%, which is little better than predicted and probably reflects the analytical precision of the laboratory of Mann et al. compared to that used in propagation of analysis.2, 3

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References

  1. Mann DV, Ho CS, Critchley L, Fok BS, Pang EW, Lam CW et al. Affordable measurement of human total energy expenditure and body composition using one-tenth dose doubly labelled water. Int J Obes (London) 2007; 31: 1004–1013.

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  2. Schoeller DA . Energy expenditure from doubly labeled water: some fundamental considerations in humans. Am J Clin Nutr 1983; 38: 999–1005.

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  3. Ritz P, Johnson PG, Coward WA . Measurements of 2H and 18O in body water: analytical considerations and physiological implications. Br J Nutr 1994; 72: 3–12.

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  4. Horvitz MA, Schoeller DA . Natural abundance deuterium and 18-oxygen effects on the precision of the doubly labeled water method. Am J Physiol 2001; 280: E965–E972.

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Authors and Affiliations

  1. University of Wisconsin-Madison, Madison, WI, USA

    D A Schoeller

  2. 2MRC-HNR, Cambridge, UK

    W A Coward

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  1. D A Schoeller
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  2. W A Coward
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Correspondence to D A Schoeller.

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Schoeller, D., Coward, W. Reduction in O-18 dose – at what cost?. Int J Obes 31, 1033 (2007). https://doi.org/10.1038/sj.ijo.0803626

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