Dennis T. Gordon

Effects of dietary supplementation with fructooligosaccharides on colonic microbiota populations and epithelial cell proliferation in neonatal pigs

Summary: Two experiments were conducted with neonatal pigs to determine the effects of feeding fructooligosaccharides on cecal and colonic microbiota, proliferation of cecal and colonic epithelial mucosa, and short-chain fatty acid concentrations in the cecum. Experiment 1 consisted of feeding neonatal pigs diets containing either 0 or 3 g fructooligosaccharides/L of formula for 15 days and then examining the large intestine for changes in cecal and proximal colonic microbiota; cecal pH; short-chain fatty acid concentrations; morphology of cecal, proximal, and distal colonic epithelial mucosa; gross necropsy; and his-topathology. Supplementation with fructooligosaccharides (FOS) did not alter cell counts of viable bifidobac-teria organisms or total anaerobic microbiota, cecal pH, or concentrations of short-chain fatty acids. Cecal mu-cosal cell density and labeled cells increased with FOS consumption. Proximal colonic mucosal crypt height, leading edge, labeled cells, proliferation zone, and labeling index increased with FOS consumption. Distal colonic mucosal crypt height, leading edge, cell density, labeling index, and labeled cells increased with FOS consumption. Gross necropsy and histopathology found no significant lesions. In Experiment 2, neonatal pigs were fed diets containing either 0 or 3 g fructooligosaccharides/L of formula for 6 days. Fecal samples were collected on the first full day of feeding and on days 3 and 6 after initiation of feeding. On days 1 and 3, concentrations of bifidobacteria were similar between diets; however, on day 6, pigs consuming FOS tended to have greater numbers of bifidobacteria (p = 0.08). These data suggest dietary consumption of FOS will enhance bifidobacteria populations and prevent colonic epithelial mucosa atrophy in neonates fed an elemental diet.

Total Dietary Fiber and Mineral Absorption

The dietary fiber hypothesis states: “A diet that is rich in foods that contain plant cell walls is protective against a range of diseases, in particular those prevalent in affluent Western Communities.” Conversely, the hypothesis implies that “in some instances a diet providing a low intake of plant cell walls is a causative factor in the etiology of the disease, and in others it provides the condition under which other etiological factors are more active” (Southgate, 1982).

ACTION OF AMINO POLYMERS ON IRON STATUS, GUT MORPHOLOGY, AND CHOLESTEROL LEVELS IN THE RAT

Previous studies have reported that aminopolymers can reduce blood cholesterol levels but may impair Fe absorption and possibly deplete Fe stores and change gut morphology. To reevaluate these findings, groups of male weanling rats were fed the American Institute of Nutrition diet containing cellulose, chitosan, chitin or cholestyramine for 21 days. Each residue was added to diets at levels of 2.5, 5, 10 and 20%. Chitosan levels, between 2.5 and 10% of the diet significantly (P≤0.05) reduced growth rate. Although diets were cholesterol free, serum cholesterol levels were significantly lower in two of the three animal groups with chitosan, in their diets. Rats fed the diet containing 10% cholestyramine died in 11 days. With 20% dietary chitosan, rats died in 6 days. A balance study revealed that the three groups of rats fed chitosan had 21% apparent Fe absorption compared to 59% observed among the other groups of animals. Hemoglobin levels were significantly lower (P ≤ 0.05) in animals fed 2.5, 5 and 10% chitosan and 10% cholestyramine compared to the other groups of animals. Liver Fe concentrations were not significantly different among groups. Results of this study indicating impaired Fe utilization caused by chitosan may be partially attributed to residual ethylene di amine tetraacetic acid (EDTA) retained by the chitosan used in preliminary sample preparation.

The Interactions among Fe, Zn and Cu Affecting Liver Cu and Femur Zn Concentrations in the Rat

Numerous studies have indicated that interactions can occur between each pair of the three transition elements, Fe, Zn and Cu (1). We have shown that a significant 3-way interaction does occur among these three elements which affected hemoglobin levels in the rat (2). The purpose of this study was to examine the effects of varying dietary concentrations of Fe, Zn and Cu on femur Zn and liver Cu concentrations in the growing rat.