The Long and Winding Road to the Best Clinical Research and Personalized Therapy With Probiotics: Do Not Forget Host Physiology.

host-specific factors such as gut transit time and gut microbiota composition determines the persistence of ingested probiotics. This study suggests several implications for clinicians and researchers using probiotics. The first is the difficulty in clinical research conducted using a probiotic. The results of previously re-ported clinical trials with probiotics are heterogeneous, even in the same disease, such as irritable bowel syndrome. 5 The claimed effects of probiotics have recently been questioned owing to the low quality of previous clinical trials by current stringent methodological standards. The low concordance between clinical studies using probiotics was mainly due to their characteristics. To date, a wide variety of