Calcium absorption in rats with distal intestinal resection: influence of type of dietary fat, cholecalciferol and nature of the adaptative response.

The effects of dietary fat and supplementation with cholecalciferol on calcium absorption at different luminal concentrations (2.07 mmol/l and 2.07 mmol/l with 0.5 mmol/l 2,4-dinitrophenol and 8.20 mmol/l) were studied in vivo in the perfused duodenum, residual jejunum and proximal colon of rats with resection of 50% of the distal small intestine, as well as the nature of the adaptative response (passive or active). Changing the source of dietary fat (diet B, containing 1/3 medium chain triglycerides, 1/3 olive oil, 1/3 sunflower oil) increased calcium absorption, preferentially via active transport, in both transected and resected rats. Supplementation of diet B with cholecalciferol further enhanced intestinal calcium absorption, especially in the colon. These results suggest the importance of diet in the adaptive processes and confirm that active mechanisms of transport adapt more readily to intestinal resection than do passive mechanisms.