Normal digestive physiology and the evaluation of digestive function.

Normal digestion is a complex and coordinated process that breaks food into constitutive molecules, some of which are absorbed and others passed through the body as waste. Many of the conditions associated with wasting syndromes alter normal digestive function and can lead to or exacerbate malnutrition. Digestive function can be defined by applying the principles of normal physiology. Our laboratory has developed a relatively comprehensive stable isotope method to assess function, which shows promise as a screening tool in evaluating patients with wasting syndromes. This and other tests of digestive function can be used to define the abnormalities associated with wasting and to direct or optimize antiwasting therapy.