Probiotics are dietary microbial mixtures that have a beneficial effect on the host by improving the intestinal microbial balance. Although a large number of microbes normally inhabit the human intestine, certain strains of bacteria have been shown to help with various conditions. Some strains have been shown to relieve acute diarrhea, inflammatory bowel disease, and irritable bowel syndrome, as well as increase the body's natural resistance to infectious diseases of the intestinal and upper respiratory tract.
Probiotics can also be used to help prevent atopic dermatitis in children.