This is an investigator-initiated, spontaneous, non-profit, randomized intervention study with two parallel arms. The study aims to evaluate the effect of a 30-days probiotic supplementation on the composition of the intestinal microbiota (MA) and the production of short-chain fatty acids (SCFAs) in faecal samples of frail elderly patients receiving home enteral nutrition (HEN) with an oligomeric formula. Participants will be monitored for gastrointestinal complications like constipation and diarrhea, and for Clostridium difficile infections.