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G A Spiller

Publications and source records attributed to G A Spiller.

At least 37 records · Page 2Linked to original sources
PubMed1979

Comparison of oral feeding of peptide and amino acid meals to normal human subjects.

Intestinal perfusion studies performed in man have suggested that amino acid nitrogen may be absorbed more rapidly from peptides than free amino acids. The aim of the present study was to compare the effects of the oral administration of peptides and free amino acids. Two isonitrogenous liquid test meals, one containing 50 g of a partial enzymic hydrolysate of fish protein in which approximately 80% of the nitrogen content was present as small peptides (peptide meal), and the other a mixture of free amino acids (amino acid meal) the composition and molar pattern of which simulated that of the peptide meal, were administered on separate occasions to six normal subjects intubated with a triple lumen tube. Both meals contained the reference marker polyethylene glycol. Fractional absorption of amino acid residues one and two hours after ingestion of the two meals was similar at three intestinal locations situated 120, 160, and 200 cm from the mouth of each subject, and at two hours 73.8% and 72.0% of the amino acid residues had been absorbed respectively by the time the contents of the peptide and amino acid meals reached the middle sampling port of the tube. The total sum of individual amino acid increments in plasma was significantly greater 30 minutes (p < 0.025) and one hour (p < 0.05) after ingestion of the peptide than amino acid meals. By three hours the total area under the two plasma curves was similar. Normal human subjects thus appeared to be capable of assimilating orally administered mixtures of peptides and free amino acids with equal efficiency. Secretion of fluid into the lumen of the upper small intestine, assessed by reference to dilution of the polyethylene glycol, was less after ingestion of the peptide meal. In clinical situations characterised by fluid and electrolyte malabsorption consideration might be given to using small peptides rather than free amino acids as the nitrogen source in nutritional diets.

Adult↗
PubMed1978

Defining dietary plant fibers in human nutrition.

Research on the nutritional aspects of dietary plant fibers in human nutrition has been plagued by many problems of definition, terminology, analytical procedures, as well as insufficient consideration of the interactions of other dietary components with the dietary fiber polymers. The use of the term non-nutritive has also led to some confusion, as many polymers of dietary fiber are digested by intestinal bacteria in humans. It appears extremely important for the orderly progress of this field that comprehensive terms be used cautiously and that perhaps a new umbrella term (such as plantix) should be introduced. The physiological effects of various polymers have been shown to differ considerably; thus the effect of dietary fiber should not be generalized. Analytical procedure should include both water-insoluble and water-soluble fractions and some consideration should be given to the non-polymeric, enzyme-indigestible compounds such as certain seed and leaf waxes.

Cellulose↗
PubMed1978

Recent progress in dietary fiber (plantix) in human nutrition.

Dietary fiber was extensively discussed in an article by G.A. Spiller and R.J. Amen in this journal in 1975 (Volume 7 Issue 1). The progress in this field has been tremendous in the past 2 years. What was an uncertain field in 1975 and what at that time to some investigators still appeared as a hypothesis or fad without much proof has turned into a much more respected part of nutritional sciences. The scientific quality of recent studies on dietary fiber in human nutrition shows a great deal of sophistication and care. Improved analytical methodologies are being used more extensively. Many nutritionists and clinicians have accepted the fact that a reasonable increase in the dietary fiber intake in the U.S. and U.K would be advisable. In this article, the possible beneficial effects of dietary fiber on health, the possible harmful side effects, and the food science aspects are carefully discussed after an update on chemistry, analytical procedures, and nomenclature. Undoubtedly, dietary fiber has found a new niche in the sciences of nutrition, medicine, epidemiology, and foods.

Adult↗
PubMed1978

Interaction of dietary fiber with other dietary components: a possible factor in certain cancer etiologies.

Dietary fiber is a highly interacting dietary component and is made up of a wide variety of enzyme-indigestible polymers: cellulose, pectins, gums, mucilages, lignin, and water-insoluble hemicelluloses. The study of the effect of dietary fiber on prevention of cancer, specifically of colonic cancer, cannot be carried on without considering that: 1) various types of dietary fiber have different metabolic effect; 2) other components of the diet (e.g., amount of fat) may influence the way dietary fiber affects the colonic environment; 3) the overall effect of dietary fiber may be the sum of effects on fecal bulk, colonic microflora pattern and metabolites, dilution of carcinogens, colonic pH, transit time, alteration of nutrient absorption, and postprandial hormonal function. It is unlikely that dietary fiber can be studied in isolation in experimental diets unless great care is taken to consider all interactions with other dietary components.

Cellulose↗
PubMed1978

Dietary fiber.

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Adult↗
PubMed1978

A double-blind study on the effect of purified cellulose dietary fiber on 1,2-dimethylhydrazine-induced rat colonic neoplasia.

The incidence, distribution, size, and histopathology of grossly visible colonic tumors induced by parenteral administration of 1,2-dimethylhydrazine were examined in rats fed either a chemically defined fiber-free diet or a nutritionally and calorically equivalent diet containing a purified fiber component, microcrystalline cellulose. This double-blind study indicates that cellulose ingestion was associated with reduced numbers of animals involved with colonic neoplasia as well as a reduction in the total numbers of colonic tumors. Furthermore, this protective effect of cellulose appears to be time dependent and associated with a shift in tumor distribution from the proximal colon to a more distal site. Cellulose fiber had no apparent effect on colonic tumor size, histopathology, or the incidence of other tumors known to occur in this experimental animal model. This study strongly supports the hypothesis that fiber is an important protective agent against colonic neoplasia development. While the mechanism for this protective effect remains obscure, it appears to be temporally related to the duration of fiber ingestion as well as to a differential fiber effect on either the luminal content or the mucosa of the proximal and distal colon.

Adenocarcinoma↗
PubMed1975

Effect of varying ratios of fat and protein in fiber-free semisynthetic diets on fecal output of pig-tailed monkeys (Macaca nemestrina).

The effect of varying the ratios of dietary fat, protein and carbohydrate on the amount and composition of fecal output was studied in adult, male pig-tailed monkeys (Macaca nemestrina) fed liquid, fiber-free semisynthetic diets. The dietary nitrogen was supplied as an enzymatic protein hydrolyzate (biological value = 86%), the fat as corn oil, and the carbohydrate as corn syrup solids. Vitamins and minerals were added to meet the nutritional requirements of this monkey. Nine diets were fed for 2 weeks, and fecal excreta collected daily after 4-day adaptation to a new diet. The levels of protein/day were 40, 80, and 160 kcal/animal and the levels of fat/day were 4.5, 22.5, and 112.5 kcal/animal. Carbohydrates were adjusted to maintain the diets isocaloric (700 kcal/day per monkey). The assumption was made that a) there was no time trend, and b) that the preceding diet had no carry-over effect on the next diet being tested. Results suggest that total fecal output was greater on the high protein diets, especially when fat levels were either 4.5 or 112.5 kcal. The 22.5 kcal fat and 160 kcal protein did not show an increase in fecal output. These fecal output differences were related to changes in fecal moisture but not in dry fecal matter. Increased nitrogen loss in the feces was noted for all 160 kcal protein diets, and especially so when the fat level was 4.5 kcal. The 112.5 kcal fat diet produced feces higher in total lipids. If a fiber-free formula diet is designed to induce a minimum of fecal bulk, the most satisfactory formulation appears to be one with a moderate amount of dietary fat, and a protein content in the general range of the recommended daily allowance.

Animals↗
PubMed1975

Effect on fecal output of various dietary nitrogen sources in pig-tailed monkeys (Macaca nemestrina) fed fiber-free, semisynthetic diets.

Fiber-free liquid diets containing isonitrogenous amounts of various dietary nitrogen sources were fed to five adult male pig-tailed monkeys (Macaca nemestrina) with a mean weight of approximately 10 kg. All liquid diets supplied 3.0 g N/DAY PER MONKEY AND MAINTAINED THE ANIMALS IN A POSTIVE NITROGEN BALANCE. Initial baseline fecal output data were obtained by feeding the animals a commercial solid monkey chow. The dietary nitrogen sources fed were a) egg white protein, b) an enzymatic hydrolysate of fish protein supplemented with L-amino acids to simulate the egg albumin pattern, c) a mixture of pure L-amino acids simulating the egg pattern, d) a casein hydrolysate supplemented with amino acids, and e) an amino acid mixture with Rose's pattern. Total fecal matter, dry fecal matter, percent of moisture, fecal nitrogen, lipids and ash were determined for a 10-day period for each experimental diet. A very significant difference (P smaller than 0.001) was noted between each liquid diet and the solid chow, but no significant differences were found between the various fiber-free liquid diets, pointing to the effect of fiber as a major factor affecting fecal output. Monkeys fed liquid diets excreted fecal matter with a mean of 12.9 g/day, of which 4.7 g/day was dry feces (fecal dry matter 28.5%). Fecal nitrogen was found to be 0.25 g, fecal lipids were 0.19 g, and fecal ash was 0.59 g/day per monkey, respectively.

Amino Acids↗