The authors review the results of various studies with probiotics on the health and physiology of human beings, including those with yogurt for lactose maldigestion, Saccharomyces boulardii and Enterococcus faecium SF 68 for antibiotic-associated diarrhoea, S. boulardii for the prevention of diarrhoea caused by Clostridium difficile, and Lactobacillus rhamnosus GG in fermented milks to shorten diarrhoea in children due to rotavirus.