Gastroenterology

Gastroenterology

Volume 127, Issue 1, July 2004, Pages 139-144
Gastroenterology

Basic-alimentary tract
A novel, noninvasive method for the measurement of intestinal fat absorption

https://doi.org/10.1053/j.gastro.2004.04.007Get rights and content

Abstract

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.

Section snippets

Diet preparation

Olestra and SPB (SEFOSE-2275) were gifts from Procter & Gamble. The fatty acids in olestra (percentage weight) is as follows: palmitic, 22.3%; stearic, 3.7%; oleic, 27.5%; linoleic, 32.9%; behenic 5.1%. The behenic acid in this olestra was included with that of SPB in all calculations in studies 1, 2, 4, and 5. The fatty acid composition of the SPB was as follows: palmitic, 2.0%; stearic, 3.1%; oleic, 7.1%; linoleic, 2.9%; arachidic, 5.1%; behenic, 77.0%. The calcium salts of stearic (63.8%)

Study 1: olestra in mice

The behenic acid in the feces collected from the safflower oil-fed animals (diet S) was in the range of 33.5%–66.4% of the total fatty acids. In this same time period, behenic acid accounted for 12.5%–19.3% of the fatty acids in the feces from the animals fed olestra and safflower oil (diet O21).

The absorption of safflower oil by the mice was calculated to be 95.9% ± 0.5% of that which was fed, based on the 17 fecal samples that were collected over the 3 days. The analyses of individual samples

Discussion

We have found that SPB is a suitable marker for the measurement of the absorption of dietary fat. It is nontoxic, commercially available, and readily measured by standard gas chromatographic methods. It was found to be a satisfactory marker for both unhydrolyzed fat (olestra) and hydrolyzed fat (calcium soaps).

Our data suggest a standard protocol for the measurement of fat in rodents, consisting of a diet containing fat and SPB for 2 nights with collection of fecal samples after the second

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Supported by a PNF Pilot and Feasibility Grant funded by the National Institutes of Health (DK59630) and by RO1 DK 56910 (to P.T.).

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