icronutrient deficiency is an area in which additional studies are needed ince the origins for micronutrient depletions in inflammatory bowel isease (IBD) are not fully understood. For example, iron deficiency in BD is generally believed to be due to chronic gastrointestinal blood loss n the presence of active IBD. Decreased duodenal and proximal jejunal ron absorption, as has been reported in celiac sprue, is not thought to be likely mechanism for iron deficiency. However, the potential effect of mall bowel bacterial overgrowth on iron absorption warrants further tudy. Other mechanisms of micronutrient depletion that we will discuss n this section include increased consumption of micronutrients, dereased biosynthesis, defects in functional transport, and protein cataboism.