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Influence of metabolic fuel on the 13 C/ 12 C ratio of breath CO 2
Author(s) -
Schoeller D. A.,
Brown C.,
Nakamura K.,
Nakagawa A.,
Mazzeo R. S.,
Brooks G. A.,
Budinger T. F.
Publication year - 1984
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200111103
Subject(s) - breath test , carbon dioxide , chemistry , δ13c , zoology , isotopic ratio , medicine , biology , physics , organic chemistry , isotope , quantum mechanics , helicobacter pylori , stable isotope ratio
Abstract Natural differences in 13 C/ 12 C ratios of various metabolic fuels can produce systematic changes in the 13 C/ 12 C ratio of breath CO 2 , and therefore introduce errors into 13 CO 2 breath tests. To gain insight into the potential problem, we compared 13 C/ 12 C ratios of plasma macronutrients to those of breath CO 2 under conditions that should alter the percentages of carbohydrate and lipid being oxidized. In rats, 48 h of starvation decreased the 13 C/ 12 C ratio of breath CO 2 by 3.5‰. At this time the 13 C/ 12 C ratio of breath CO 2 was very similar to that of plasma lipids. In humans, 30 min of heavy exercise increased the breath 13 CO 2 / 12 CO 2 ratio by 1.3‰. These changes in breath 13 C/ 12 C ratios could be predicted from 13 C/ 12 C ratios of plasma macronutrients and the percentage of carbon dioxide derived from each macronutrient, but only when compared within the same populations. For example, the 13 C/ 12 C ratios of plasma macronutrients of residents of Chicago, Illinois (USA) and Tokyo (Japan) differed by 1–3‰. An empirical correction of 13 CO 2 breath test data is recommended when breath tests are run under conditions that will change metabolic fuel utilization.