ISSN:
1573-9104
Keywords:
soy flour
;
soy protein isolate
;
trypsin inhibitor
;
pancreas
;
Wistar rat
;
hyperplasia
;
acinar adenoma
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract In two year feeding trials, histologic changes in the pancreas of the Wistar rat were evaluated after chronic dietary exposure to raw and heated, dehulled, defatted soy flour and soy protein isolates which provided a range of trypsin inhibitor (TI) concentrations from 93 to 1271 mg/100 g diet. Also investigated was the nutritional interaction of level of dietary protein with the development of pancreatic pathology. Graded levels of TI were achieved from mixtures of raw and heated soy flour or protein isolate. Dietary protein levels were 10%, 20%, and 30%; the two higher levels obtained in some diets through casein supplementation. A total of 26 diets, including casein controls, were fed to groups of 40 male rats. Growth rates with these diets were commensurate with protein quality and level. Mortality rates tended to be slightly greater in the higher protein diets, and rats fed only raw soy as a source of protein survived well. Two lesions, nodular hyperplasia (NH) and acinar adenoma (AA) constituted the major pathological findings in the pancreas, and the incidence rates of both were positively associated with the concentration of dietary TI. The incidences of pancreatic NH and AA compared to those of the corresponding casein control were significantly elevated in rats fed heated soy flour supplying 10% protein and the lowest level of TI investigated (93 mg/100 g diet). At low levels of TI (≦215 mg/100 g diet), supplementation by casein to raise the concentration of protein from 10% to 20% and 30% reduced the frequency of NH and AA. When the dose-response data for NH and AA was linearized by plotting the probit of percent incidence against log of TI concentration per gram of dietary protein, the response to soy flour and soy protein isolate was not significantly different. Numerous lesions commonly found in the aging rat were diagnosed, and modulation of their rate of occurrence by nutritional factors associated with the diets was apparent in some instances.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01092199
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