The gut microbiome is meant to influence various compartments, organs and functions of the body. In animals, feed and feed additives can influence the landscape of microorganisms present in the gastrointestinal tract. In diseased animals, specifically designed products may beneficially affect the gut flora. Sabine Richter, Dr. Regina Wolf and Dr. Klaus Hellmann at Klifovet AG focus on the regulatory options available and the different opportunities for such products.