"Pro" means "for" or "in favour of," "biotic" means "life." Thus, probiotic means "for/in favour of life." It contrast directly with "anti," "biotic" or "killing life." The Nobel Prize winning Russian scientist Elie Metchnikoff first conceptualised probiotics; defined as viable microorganisms that are beneficial to human health, at the turn of the 20th century. He believed that the fermenting bacillus (now called Lactobacillus bulgaricus) contained in the fermented milk products consumed by Bulgarian peasants positively influenced the micro flora of the colon, thus decreasing toxic microbial activities. Lilly and Stillwell probably first introduced the term “probiotics” in 1965, as growth promoting factors produced by microorganisms. However, the term ‘probiotic’ was popularised by R. Fuller in 1989 and defined as a live microbial feed supplement, which beneficially affects the host by improving its intestinal microbial balance. This definition was later extended to include other beneficial effects such as immunomodulation. There is a popular view that probiotics are the "medicine" of the twenty first century. The World Health Organization (FAO/WHO, 2002) has defined probiotics as live microorganisms, which when administered in adequate amounts confer a health benefit.