X-Message-Number: 10037 Date: Sat, 11 Jul 1998 09:02:11 -0700 (PDT) From: Doug Skrecky <> Subject: metabolism of sugar alcohols Quote from (Regulatory Toxicology and Pharmacology 24: S198-S205 1996): "Erythritol is a tetritol, i.e. a 1,2,3,4-butanetetrol. As such, erythritol ranks in the homologous series of the monosaccharide sugar alcohols between the only existing triitol (glycerol) and the four stereoisomeric pentitols (xylitol, ribitol, and d- or l-arabitol). Among the three stereoisomeric tetritols, erythritol (syn.: meso-erythritol) is the one which is optically inactive (the other two being d- and l-threitol). Glycerol has a small molecular volume; it is therefore readily, and thus completely, absorbed from the intestinal tract. The pentitols, on the other hand, have a larger molecular volume; their uptake by passive diffusion - through hydrophilic "pores" of the cell membranes (transcellular pathway) and/or through the "tight" junctions between the intestinal epithelial cells - proceeds therefore at a much lower rate and thus is incomplete. For erythritol, which has a molecular volume between that of glycerol and the pentitols, an intermediate diffusion rate is to be expected. Experiments of others, which were published after completion of this study, indicate indeed that about 65-90% of an ingested U-14C-erythritol dose is absorbed by rats. The absorbed portion of monosaccharide sugar alcohols is metabolized rather quickly (glycerol, ribitol, xylitol, sorbitol), slowly (l-arabitol), or not to any relevant extent (erythritol, d-arabitol, mannitol). Because of their hydrophilicity and chemical inertness, absorbed yet not metabolized sugar alcohols are readily excreted with the urine in unchanged form. The unabsorbed fraction of sugar alcohols is fermented in the large intestine by the gut microflora to short-chain fatty acids which are absorbed almost completely and are metabolized in the body by ordinary metabolic pathways." Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=10037