Bifidobacterium bifidum, known as B. bifidum, is a strain of bacteria commonly used as a probiotic. Probiotics are living microorganisms that simulate the beneficial bacteria found in the gastrointestinal tract of humans. B. bifidum is one of many bacterial strains that occur naturally in the gut flora, living in the colon. The inclusion of B. bifidum in a dietary regimen provides the host with a variety of benefits.