Towards understanding the process of intestinal adaptation.

When bowel is lost due to disease or surgery, the residual bowel increases its functional capacity in order to compensate for the loss of absorptive capacity. The success and extent of this adaptive process is critical to recovery. This article reviews the current understanding of the intestinal adaptation. Adaptation is a complex process which as yet is poorly understood and thus it is difficult to develop strategies to enhance the out-come of the adaptation phase. Extensive loss of bowel brings about functional as well as morphologic changes in the remaining intestine. The exact relationship between histologic changes and function is still unknown and some studies show that histologic changes may precede functional changes. Both nonnutritive and nutritive factors have been identified as major stimuli to the adaptive process. The importance of oral intake as a positive stimulus has been demonstrated and the role of diet composition rather than diet complexity being recognized. Recent studies attempt to understand the molecular basis of intestinal adaptation by seeking to characterize the nature of humoral factors involved and to establish alterations in the patterns of gene expression. These new approaches may facilitate the identification of both nutritional and pharmacological methods to manipulate the intestinal adaptation process.