Comparison of Feeding Unrefined and Refined Starch Diets on Intestinal Upake and Hepatic Lipogenic Enzymes in the Rat

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Abstract
The rates of intestinal uptake of dietary sugars and amino acids, and changes in serum insulin and hepatic lipogenic enzyme responses were determined in male Wistar rats fed either an unrefined starch (stock) diet or a 65% readily digestible refined starch (corn) or a poorly digestible refined starch (potato) diet. At 45 days of age, rats fed the corn starch diet had 30% to 50% higher fasting serum insulin levels than did rats fed the stock or potato starch diets; however, the differences were not statistically significant. After an average of 9 weeks of being fed the diets, the intestinal uptake of glucose, α-methylglucose and fructose, and the response of hepatic malic enzyme and glucose-6-phosphate dehydrogenase were significantly greater in rats fed the corn starch diet than in rats fed the stock diet, whereas the effect was opposite with leucine and galactose uptake. The intestinal uptake of sugars and amino acids, and hepatic enzyme responses were often similar in rats fed the stock or potato starch diets. Rats fed the potato starch diet had smaller livers than did rats fed the corn starch diet. The livers of rats fed the corn starch or potato starch diets contained less soluble protein than did the livers of rats fed the stock diet. Feeding of the potato starch diet resulted in an abnormally enlarged and bloated gastrointestinal tract and in constrictions of the small intestine which appeared to obstruct the flow of intestinal contents.