Congress of Nutrition, at Adelaide, SA, Australia, on September. 23-25, 1993. Guest editors for this symposium were Kay Earle,. John Mercer and D'Ann Finley.
Dietary Fiber
Composition of Meal Influences Changes in Postprandial Incremental Glucose and Insulin in Healthy Dogs12 PATRICK NGUYEN*3
HENRI DUMON,*
PIERRE BUTTINJ
LUCILE MARTIN*
AND ABDOULAYE S. GOÜROÕ 'Department of Nutrition, École nationale vétérinaire de Hantes, Hantes, France, tRoyal Canin R. & D. France, and ^Department of Animal Production, Faculty of Agronomy, Niamey, Niger
INDEXING KEY WORDS: •dog foods •glycémieindex index •dogs
•insulinemic
The extent of postprandial hyperglycemia and in sulin secretion depends on many factors. This has been well established in human beings and their food has been systematically classified according to their gly cémie responses. Due to its clinical implications, no tably in diabetes management, the factors affecting the glycémie index of foods have been the subject of many studies (Wolever et al. 1991). The development of postprandial hyperglycemia depends on the amount of food and carbohydrates consumed per meal. However, different kinds of car bohydrates elicit different glucose and insulin concen trations, because their chemical nature (amylose, 0022-3166/94
amylopectin) may affect their rate and speed of diges tion (Behall et al. 1989, Goddard et al. 1984). Dietary fiber reduces acute postprandial rises in these re sponses by slowing down the rate of passage and the rate of hydrolysis of starchy polysaccharides (Nishimune et al. 1991, Wolever 1990). Dietary fat also has an influence by delaying stomach emptying (Welch et al. 1987). High intakes of rapidly digested proteins modify the glycémieresponse by increasing insulin secretion, because of the effects of amino acids (Nuttal and Gannon 1990). Another important factor is the type of food processing, especially in dog food. The type of food, dry, canned or soft moist, affects the maximal postprandial glucose concentration as much as the time at which this peak occurs (Holste et al. 1989). The evaluation of the effects in dogs of complete foods differing in their composition appears to be a further step in the assessment of adequate energy feeding and in the prevention of obesity, the most common nutritional disorder occurring in these ani mals. Indeed, if, in the absence of primary hormonal disorder, the first determinant of obesity is a long-term excessive energy intake, food quality is also important because of its humoral and metabolic effects (Flatt 1988, Schutz et al. 1989). Information on postprandial glycémie and insulinemic increases may also be of in terest in the management of non-insulin-dependent diabetes mellitus (which elicits alteration of carbo hydrate tolerance and insulin action) as much as in sulin-dependent diabetes mellitus (reduction of fluc1 Presented as part of the Waltham Symposium on the Nutrition of Companion Animals in association with the 15th International Congress of Nutrition, at Adelaide, SA, Australia, on September 23-25, 1993. Guest editors for this symposium were Kay Earle, John Mercer and D'Ann Finley. 1 Supported in part by Royal Canin S.A. 3 To whom correspondance should be addressed: Department of Nutrition, École nationale vétérinaire de Nantes, Case postale 3013, 44087 Nantes Cedex 03, France.
$3.00 ©1994 American Institute of Nutrition.
2707S
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ABSTRACT Postprandial hyperglycemia and insulin secretion depend on many factors, such as food com position, carbohydrate type and processing. The pur pose of this study was to evaluate the effects of foods differing in composition in nonobese clinically normal dogs. These dogs were offered in a single meal one of the four foods. Blood samples were collected before feeding and during the 180 min after the meal. Plasma glucose and insulin concentrations were determined. The integrated areas under the postprandial glucose and insulin response curves were calculated. Times to response peaks, maximum plasma insulin elevation, area under the insulin response curve and the insulinemic index differed between dog foods. Crude fiber con tent had no significant effect. The time to glucose peak was higher and the time to insulin peak lower with the food highest in protein and ether extract content. The time to glucose peak was correlated to protein, fat and nitrogen-free extract content of foods, whereas the time to insulin peak and the area under the insulin curve were correlated to protein and nitrogen-free extract. J. Nutr. 124: 2707S-2711S, 1994.
2708S
SUPPLEMENT
tuations in blood glucose, synchronization of glucose increase and insulin administration). In human beings, glycémie index values for food are very similar in healthy, insulin-dependent and non-insulin-dependent diabetes mellitus patients (Indar-Brown et al. 1992; Wolever et al. 1987). The present study was primarily designed to eval uate the effects of commercial foods that differ in composition and were given on a normoenergetic ba sis, on glycémieand insulin responses in normal dogs.
MATERIAL
AND METHODS
±SD) and their response to the intravenous glucose tolerance test (performed after a 24-h food-deprived period), using a glucose dose of 500 mg-kg body weight"', infused as 50% glucose solution in 30 s, were also normal. These dogs were accustomed to the experimental procedure. They were commonly used for digestibility trials in the cages used in this study and previous been submitted to repeated venapuncture. Therefore, their responses were due to the experimental variables and not to stress. Experimental diets. Four experimental foods (D, Cl, C2 and C3 foods) were tested (Table 1). Food D was a dry food, whereas other foods were canned. These foods differed in their composition (29.0-41.1% crude protein, 8.2-25.7% ether extract, 2.1-10.8 crude fiber and 15.5-48.4 nitrogen free extract, on a dry matter basis) and their energy breakdown (27-38% energy derived from protein, 20-52% from fat and 13-47% from nitrogen-free extract, according to stan dard energy conversion factors). Design and procedures. Before the initiation of the study, the dogs consumed in a single meal the same dry food consisting of 27.2% crude protein, 10.9% ether extract, 1.6% crude fiber and 48.0% nitrogen free extract on a dry matter basis for 2 wk. On the morning of the test days and after a 24-h food-deprived period, they were again given, in a single meal, one of the four experimental foods. The size of the meal was determined by the size of the individual dog (31.6 kj metabolizable energy/kg metabolic BW°rs).One hour before feeding time, each dog was placed in a separate cage. Each dog consumed all of the food in
