Gangliosides are glycosphingolipis that are widely distributed in vertebrate tissues and body fluids and which are specially abundant in neural tissues. Milk from different species has a particular ganglioside content and profile. Human milk has a higher content of gangliosides than bovine milk. GD, and GM, are the predominant individual gangliosides in bovine milk. In human colostrum GD, is also the main ganglioside whereas in human mature milk GM, predominates over the other gangliosides. Human mirk also contains GM, and a number of highly polar gangliosides, which may play an important role in infant physiology. GM, has been shown to inhibit Escherichia coli and Vibrio cholerae enterotoxins. We have found that a ganglioside-supplemented infant formula modifies the intestinal ecology of preterm newborns, increasing the Bifidobacteria content and lowering that of Escherichia coli, Although the exact mechanism by which dietary gangliosides reduce the fecal content of Escherichia coli is unknown, in vitro experiments suggest that they may act as false intestinal receptors for some strains of this bacteria. Since GD, and other gangliosides have been involved in mechanisms of lymphocyte activation and differentiation, dietary gangliosides might have a function in intestinal immunity development. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.