"Good" bacteria that live in our intestines have been linked with a variety of health benefits, from fighting disease to preventing obesity. In a new study, Kriston Ganguli of Massachusetts General Hospital for Children and Harvard Medical School and her colleagues have discovered another advantage to these friendly microscopic tenants: Chemicals secreted by good bacteria that typically live in the intestines of babies could reduce the frequency and severity of a common and often-lethal disease of premature infants.