Trimethylglycine has two primary metabolic roles: it is a methyl group donor and an osmolyte that assists in cellular water homeostasis. Tissues that rely on zwitterionic betaine as an osmolyte include the intestines, kidney, liver, brain and leukocytes. Osmolytes are particularly important in situations in which cellular dehydration is present because these compounds help minimize water loss despite a prevailing osmotic gradient. Thus, water balance homeostasis is an important factor for cells exposed to a variety of osmotic conditions (Klasing et al., 2002). For example, the osmotic pressure of the intestinal contents varies during the process of digestion. The osmotic difference between the intestinal epithelium and the luminal fluid is likely to necessitate means to control the osmotic pressure inside the intestinal epithelial cells. Betaine, as an organic compatible osmolyte, is one of the most likely candidates for the task.