Background: Fusobacterium spp. are known to be part of mouth and intestinal microbiota. Fusobacterium nucleatum is an obligate anaerobe, Gram negative, non-spore forming pleomorphic bacillus that can cause diseases not only in the mouth and teeth but also in the brain, pleura, lungs and liver. It was noted that F. nucleatum induces fetal death (fetal demise) in pregnant women. Recent studies indicate that F. nucleatum could lead to colon cancer by binding to the epithelial tissue. Kefir is produced from kefir grains that are a source of probiotics. Fermented dairy products and especially kefir and yogurt are significant for functional nutrition. In kefir grains, lactic acid bacteria, acetic acid bacteria and yeasts are embedded in a polysaccharide matrix, called kefiran. When kefir grains are added to milk and incubated for approximately 22 h at 25 degrees C, microorganisms in the grains continue to proliferate in milk with the production of functional metabolic compounds. While yogurt has mainly two bacteria, authentic kefir has its characteristic Lactobacillus kefiranofaciens, Lactobacillus kefir and Lactobacillus kefirgranum, in addition to many other types of lactic acid bacteria (LAB). Previous studies have indicated that fermented dairy products can cause probiotic effects such as improvement in digestive system health, reduction in serum cholesterol, improvement in lactose tolerance, improvement in immune function, control of irritable bowel symptoms, and anticarcinogenic properties.