Erythritol occurs widely in nature and has been found to occur naturally in several foods including wine, sake, beer, watermelon, pear, grape, and soy sauce. Evidence indicates that erythritol also exists endogenously in the tissues and body fluids of humans and animals. Erythritol is absorbed from the proximal intestine by passive diffusion in a manner similar to that of many low molecular weight organic molecules which do not have associated active transport systems. The rate of absorption is related to their molecular size; erythritol, a 4-carbon molecule, passes through the intestinal membranes at a faster rate than larger molecules such as mannitol or glucose. In diabetics, erythritol has also been shown to be rapidly absorbed and excreted unchanged in the urine. Following absorption, ingested erythritol is rapidly distributed throughout the body and has been reported to occur in hepatocytes, pancreatic cells, and vascular smooth muscle cells. Erythritol also has been reported to cross the human placenta and to pass slowly from the plasma into the brain and cerebrospinal fluid , 36(12), 1139-1174.). Erythritol is found to be associated with ribose-5-phosphate isomerase deficiency, which is an inborn error of metabolism.