Potato starch and caecal hypertrophy in the rat

Abstract

Raw and milled potato starch caused caecal enlargement of up to 800% when fed to rats as the sole carbohydrate source in synthetic diets containing 16–24% protein and 71-63% carbohydrate. Control animals received maize starch in the diet. Caecal enlargement was dose-related. The hypertrophy was reversible and caeca approached control size within 11 days of the replacement of potato starch by maize starch. Some deaths occurred in groups of animals receiving raw potato starch at dietary levels of 30% or more. A total of 21% of the animals receiving these levels of raw potato starch died, while no deaths were observed in control animals. There were no significant differences between test and control animals in potassium concentrations and osmolalities of caecal contents, or in serum electrolyte and urea concentrations. Activities of serum glutamic-pyruvic transaminase and alkaline phosphatase were significantly higher in test animals but the histology of the liver, gastrointestinal tract and kidney were apparently normal. Caecal distension resulted in pressure on the diaphragm and impaired respiratory function, as indicated by a higher arterial blood pCO 2 and lower pO 2 and an increase in lactate concentration in venous blood. It is suggested that impaired respiratory function may have played an important role in the deaths associated with dietary potato starch and caecal enlargement.