A method of treating irritable bowel syndrome using a probiotic composition including the bacilli (1) Bacillus subtilis, (2) Bacillus coagulans, and (3) Enterococcus faecium. The composition may further include a carrier medium, such as fructo-oligo-saccharides (FOS), as incorporated in a dose form such as a pill, capsule, powder or sachet. The compositions of the invention may be usefully employed as health or nutritional supplements, food additives, or therapeutic agents for combating a wide variety of physiological disorders.