ALTERATION OF THE FIBER AND LIPID COMPONENTS OF A DEFINED-FORMULA DIET - EFFECTS ON STOOL CHARACTERISTICS, NUTRIENT DIGESTIBILITY, MINERAL BALANCE, AND ENERGY-METABOLISM IN HUMANS

Eighteen healthy males with a body weight of 70.0 +/- 3.1 kg consumed three defined-formula diets that varied only in their fiber and/or lip id components: 1) 6.4% fiber (100% soy polysaccharides) and 13.1% lipi d [50% medium-chain triacylglycerols (MCTs), 40% corn oil, and 10% soy oil]; 2) 3.4% fiber (75% oat fiber, 17.5% gum arabic, and 7.5% carbox ymethylcellulose) and 15.6% lipid (20% MCTs, 50% canola oil, and 30% h igh oleic acid safflower oil); and 3) 4.4% fiber (same as diet 2) and 14.5% lipid (same as diet 1). Consumption of diet 2 resulted in slight ly firmer stools and provided the greatest amount of fecal output per unit fiber intake. Total dietary fiber (TDF) digestibility was lowest for men fed diets 2 and 3, but nitrogen and lipid digestibilities and energy metabolism criteria were not different among diets. Although mi neral excretion patterns differed among treatments, fiber and lipid co mponents of the diets appeared not to be responsible for these differe nces. Results indicate that fecal output can be maintained with a lowe r intake of a blend of oat fiber, gum arabic, and carboxymethylcellulo se compared with soy polysaccharides. Except for TDF digestibility, al teration of amounts and/or sources of fiber and lipid components of de fined-formula diets used in this experiment did not alter nutrient dig estibility, energy metabolism, or mineral retention.