Probiotics are dietary microbial mixtures that beneficially affect the host by improving intestinal microbial balance. Although large numbers of microbes normally inhabit the human intestine, certain strains of bacteria have been shown to assist with various conditions. Certain strains have demonstrated the ability to alleviate acute diarrhea, inflammatory bowel diseases, and irritable bowel syndrome, as well as being able to increase the body’s natural resistance to infectious diseases of the intestinal tract and upper respiratory tract. Probiotics can also be used to help prevent atopic dermatitis in children.