A novel, noninvasive method for the measurement of intestinal fat absorption

Background & Aims: The goal of the study was to facilitate fat balance measurements with an appropriate intestinal marker for the transit of dietary fat and thereby eliminate the need for complete diet and fecal collections. Methods: Dietary fat containing 5% sucrose polybehenate was fed in a semisynthetic diet to rats and mice. Fat absorption was calculated from the ratios of behenic acid to other fatty acids in diet and feces as analyzed by gas chromatography of fatty acid methyl esters. The method was validated by measuring absorption of well-absorbed (safflower oil) and poorly absorbed (olestra; calcium soaps) dietary fats. The animals were fed meals containing test fats for 2 or 3 days, and fecal samples were collected. Fecal samples of approximately 10 mg (single fecal pellet from mice) were assayed. Results: The method yielded values that were consistent with complete absorption of safflower oil and the nonabsorbability of olestra and calcium soaps. The results were reproducible and consistent among individual fecal aliquots. The method was compared with traditional fat-balance methods in animals fed both high- and low-fat diets. Conclusions: Sucrose polybehenate is an appropriate marker that allows the rapid measurement of fat absorption by analyzing aliquots of <1% of total feces. The method is noninvasive, does not require isotope analyses, and can be carried out as part of an animal's normal feeding regimen. The method may be a facile technique to assess fat absorption measurements in humans.