The invention covers a novel treatment strategy that considerably improves conventional probiotic treatments of inflammatory bowel diseases, irritable bowel syndrome and other gastrointestinal disorders. Both probiotic microorganisms and the carrier of the probiotic microorganisms in form of a fermented cereal gruel are used as treatment effectors. Phospholipids may also be an effector. The novel treatment strategy is capable of removing the symptoms of inflammatory bowel diseases regardless of a mild, moderate or severe stage of the disease.