The supplements administered consisted of one of three dietary fibers or a placebo. The dietary fibers were gum arabic, psyllium, and CMC. The compositions of the fibers are described in Table 1. The fibers were selected because they represent three levels of fermentation (low, medium and high) by fecal bacteria. A total of 16 g of total dietary fiber was administered daily. The amounts of the fiber sources needed (17.3 g gum arabic, 16.8 g psyllium, and 21.5 g CMC) were determined from the initial analysis of their fiber content. The supplements were prepared as a fruit juice mixture and a small muffin, each taken twice daily at the morning and evening meals. Subjects were able to select a preferred juice flavor and muffin spice from a set of offered choices. Each of the two juice mixtures contained 270 ml (9 oz.) of juice diluted to half the concentration recommended on the can. The two juices together provided a total of 7 g of total fiber that was divided approximately equally between them. The two muffins provided 9 g of total fiber, approximately 4.5 g of total fiber in each. The placebo juices contained half-strength juice only and the placebo muffins contained the ingredients of the basic recipe only. Subjects and data collectors were blinded to the type of fiber administered and its distribution in the juice and muffin.