The gastrointestinal handling and metabolism of [1-13C]palmitic acid in healthy women.

The gastrointestinal handling and metabolism of [1-13C]palmitic acid given as the free fatty acid was examined in six healthy women by measuring the excretion of 13C-label in stool and in breath as 13CO2. The gastrointestinal handling of [1-13C]palmitic acid was compared with the apparent absorption of dietary lipid by measuring lipid losses in stool. The variation both within and between subjects was determined by repeating the study in the same individuals on separate occasions. The time course for excretion of label in stool over the five-day study period followed a common pattern, with most of the label excreted over the first two days of the stool collection. 13C-Label excreted in stool over the five-day study period was 14.3 +/- 9.8% of that administered and on repeating the trial was 31.6 +/- 24.7% (not significantly different due to variability); there was poor agreement within subjects. Lipid excreted in stool expressed as a percentage of ingested lipid was 5.2 +/- 4.4% in Trial 1 and 5.9 +/- 4.0% in Trial 2, and was the same in each individual on repeating the trial. There was no clear relationship between the excretion of 13C-label and lipid in stool (Trial 1: R = -0.43, P > 0.40; Trial 2: R = -0.02, P > 0.97). On the first occasion, 22.0 +/- 4.5% of the administered label was excreted on breath over the 15-h study period and on repeating the trial was 15.8 +/- 9.5% (not significantly different) with poor repeatability in a given individual.(ABSTRACT TRUNCATED AT 250 WORDS)