In a double blinded crossover study we did find any changes in the gut microbiota as a consequence of probiotic intake. Therefore we hypothesize that the effect detected is a direct effect of the probiotics.
Read more in Probiotics, symptoms, and gut microbiota: what are the relations? A randomized controlled trial in subjects with irritable bowel syndrome. Gastroenterol Res Pract. 2012;2012:214102. Epub 2012 Jul 31.Farup PG, Jacobsen M, Ligaarden SC, Rudi K.