The invention relates to supporting the growth or maintenance of oxygen-sensitive bacteria in the gastrointestinal tract of an animal. Provided is riboflavin, riboflavin phosphate or a salt thereof, for use in a method for the selective stimulation of Faecalibacterium prausnitzii in the gastrointestinal tract in an animal. Also provided is riboflavin for use in a method for preventing, treating or reducing the symptoms associated with an inflammatory gastrointestinal disorder, the method comprising administering to a human subject in need thereof an amount of riboflavin effective to maintain, support or stimulate the growth of F. prausnitzii in the gastrointestinal tract.
