Probiotics Beneficial Intestinal Bacteria Flora such as Lactobacillus acidophilus. Probiotics are defined as "Live microorganisms which when administered in adequate amounts confer a health benefit on the host." Lactic acid bacteria and bifidobacteria are the most common types of microbes used as probiotics Some yeasts and bacilli may also be helpful. Probiotics are commonly consumed as part of fermented foods with specially added active live cultures; such as in yogurt, soy yogurt, or as dietary supplements. Probiotics are generally regarded as beneficial for proper and healthy digestion.