ABSTRACT
Digestion can be de˜ned as the mechanical and enzymatic breakdown of foods into simpler chemical compounds that can be absorbed and assimilated by the body. Intestinal absorption is the uptake of Žuids, solutes, proteins, fats, vitamins, minerals, and other trace elements from the intestinal lumen into intestinal epithelial cells, blood, or lymph or interstitial Žuids. There are three steps required for normal nutrient absorption: luminal processing, absorption into the intestinal mucosa, and transport into the circulation [1]. Malabsorption is de˜ned as impaired intestinal absorption of nutrients from food, which can result from a broad spectrum of diseases [2]. It involves the failure to absorb speci˜c isolated nutrients such as sugars, fats, proteins, or vitamins, or it can be an impaired absorption of food that may lead to generalized nutritional de˜ciency. Malabsorption syndromes include diseases causing an alteration of digestive processes, and diseases causing an alteration in the uptake and transport of nutrients due to injury or reduction of the absorption surface [3]. Another factor that can interfere with nutrient absorption is maldigestion, which is the impaired digestion of nutrients within the intestinal lumen or at the terminal digestive site of the brush border membrane of mucosal epithelial cells. Although malabsorption and maldigestion are pathophysiologically different, the processes underlying digestion and absorption are interdependent, so that in clinical practice the term malabsorption is often used to describe a defect in either process.
