Fiber supplementation of enteral formulas: effects on the bioavailability of major nutrients and gastrointestinal tolerance.

Two fiber-supplemented enteral formulas were recently introduced for patient application, Susta II and Enrich (12.4-g and 38.5-g soy polysaccharide/2000 kcal, respectively). This investigation had a 3-fold purpose: to determine if and to what extent fiber-supplementation changes the chemical composition of stool relative to a fiber-free formula (Ensure); to establish the clinical tolerance of the two new formulas; and to quantify the effects of soy polysaccharide on nutrient bioavailability. The study was conducted in two consecutive phases: A (n = 6 subjects; random assignment to either Ensure or Susta II for 1-2 weeks followed by isocaloric cross-over to the alternate formula for an equal period of time) and B (n = 8 subjects evaluated as in phase A except Enrich replaced Ensure). Each balance week consisted of clinical/subjective monitoring, evaluation of stool composition (H2O and dry weight), apparent nutrient absorption (energy, fat, N, P, K, Ca, Mg, Zn, Na, and Cl), and metabolic balance (N, P, K, Ca, Mg, Na, and Cl). Relative to the fiber-free formula the two fiber-supplemented solutions produced increases in fecal N, fat, H2O, and minerals of variable magnitude; there were corresponding reductions in net absorption of organic compounds and minerals. The additional minerals added to the fiber-supplemented formulas and the minimal effects on N absorption preserved balance; the retention of N, P, K, Ca, Mg, Na, and Cl were similar for all three formulas. No adverse clinical effects of the fiber-supplemented formulas were noted.(ABSTRACT TRUNCATED AT 250 WORDS)