The study revealed that there was an increase in the numbers of Proteobacteria, a large phylum [group] of microbes, in the intestines of mice drinking water supplemented with Splenda. Half of the mice studied, belonging to a genetic line that suffers a form of Crohn's disease were more affected than the remaining half of mice, which belong to a healthy mouse line. Splenda produced the intestinal overgrowth of E. coli (a member of the Proteobacteria group) and increased bacterial penetration into the gut wall, but only in Crohn's disease-like mice.