Colief Infant Digestive Aid is a natural product which is added to infant milk and used to treat temporary lactose intolerance (TLI) in babies suffering from colic. The active ingredient is lactase, a safe, naturally occurring substance produced within the small intestine. Lactose intolerance in new-born babies can lead to digestive discomfort - bloating, gas and griping pain - which results from undigested lactose in food. This can be an important factor in some babies with colic.