13C-ethanol and 13C-acetate breath tests in normal and aldehyde dehydrogenase deficient individuals

Four normal and five aldehyde dehydrogenase (ALDH) isozyme I deficient individuals were subsequently loaded with (1-13C)ethanol and (1-13C)sodium acetate and the conversion of the label to 13CO2 was determined in expired air by isotope ratio mass spectrometry. In the 13C-acetate breath test, both groups showed virtually identical recovery of the label in expired air, namely 48.5 +/- 2.3% (mean +/- S.D.) for normal and 46.8 +/- 5.7% for deficient individuals. However, in the 13C-ethanol breath test, both the groups performed differently. On average, although a certain overlap of the single data was observed, the recovery of the label after four hours was 43.4 +/- 3.8% for the normal and 35.6 +/- 6.8% for the ALDH deficient subjects. These findings suggest a slower conversion of ethanol to carbon dioxide in aldehyde dehydrogenase deficient individuals, which may be another consequence of this deficiency besides the higher plasma acetaldehyde levels observed after ethanol loading in comparison to individuals with normal aldehyde dehydrogenase activity.