TRIAL OF NEAR-INFRARED REFLECTANCE SPECTROSCOPY IN A HUMAN FIBER DIGESTIBILITY STUDY

A trial of near-infrared reflectance spectroscopy (near-IRS) to predic t fecal concentration of dietary fiber (DF) in humans was performed. F ecal samples from 34 persons consuming 6 diets of known DF content wer e scanned by near-IRS. Diets consisted of a liquid nutrition supplemen t and quick breads containing either 0 g of fiber, 10 g of wheat bran, 30 g of wheat bran, 10 g of vegetable fiber mix, 30 g of vegetable fi ber mix, or 30 g of sugar beet fiber. Neutral detergent fiber (NDF) de terminations were made on all fecal samples. An equation to predict ND F concentration was derived from 109 fecal samples using modified part ial least-squares analysis. Neutral detergent fiber concentrations pre dicted from near-IRS data were compared to observed NDF concentrations of 75 other samples to validate the equation. Comparison of observed vs predicted NDF revealed nearly perfect correlation between the two. Calibration and validation of a near-IRS equation generally requires t hat tradiational chemical analysis be done on only two subsets of samp les, thereby reducing the time and effort needed to analyze DF concent rations. This study demonstrates that near-IRS is a viable tool for st udying DF digestibility in vivo in humans.