A protein-free diet alters small intestinal architecture and digestive enzyme activities in rats.

The consequences of feeding a protein-free (PF) diet, as compared to casein, on gut characteristics were studied in slightly energy-restricted rats fed similar amounts of feed for 10 d. The weight and pH of fresh digesta in the stomach were lower (P = 0.045 and P = 0.016). However, the weight of fresh digesta in the other segments and gut tissue weight were not significantly affected by the diet (P > 0.05). Small intestinal crypt depth, width and area were reduced by 13, 23 and 37%, respectively (P = 0.011, P = 0.004 and P = 0.001), and villus width tended to be smaller (P = 0.057), with the PF diet. Villus height to crypt depth ratio was also lower with the PF diet in the duodenum and ileum, respectively (P < 0.05). Finally, the specific activities of alkaline phosphatase and aminopeptidase N were reduced by 36 to 38% at different sites of the small intestine in the rats fed the PF diet (P < 0.05). In conclusion, chronic consumption of a protein-free diet altered the intestinal villus-crypt architecture and enzyme activities in rats.