Kefir

Kefir contains several major strains of friendly bacteria not commonly found in yogurt, Lactobacillus Caucasus, Leuconostoc, Acetobacter species, and Streptococcus species.
It also contains beneficial yeasts, such as saccharomyces kefir and torula kefir, which dominate, control and eliminate destructive pathogenic yeasts in the body. They do so by penetrating the mucosal lining where unhealthy yeast and bacteria reside, forming a virtual SWAT team that house-cleans and strengthens the intestines. Hence, the body becomes more efficient in resisting such pathogens as E. coli and intestinal parasites.
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Kefir’s active yeast and bacteria provide more nutritive value than yogurt by helping digest the foods that are eaten and by keeping the colon environment clean and healthy. Because the curd size of kefir is smaller than yogurt, it is also easier to digest, which makes it a particularly excellent, nutritious food for babies, the elderly and people experiencing chronic fatigue and digestive disorders.
Milk kefir is made with cow milk, goat milk or coconut milk. It may also be made with other non-dairy milks, though results may be inconsistent. A starter culture is also needed such as milk kefir grains.  

Water kefir, like kombucha, is first cultured by introducing a SCOBY (symbiotic culture of bacteria and yeasts) into sugar water. The beneficial bacteria and yeasts present in the water kefir grains metabolize the sugar, turning it into an array of beneficial acids and infusing it with beneficial microorganisims, additional B vitamins as well as food enzymes.