Kefir grains are a symbiotic mixture of different microbial species and groups. The predominant ones are lactic bacteria; found in dairy products like yogurts, cheese or milk kefir. Most detected species are Lactobacillus delbruekii, Lactobacillus kefiranofaciens, Lactobacillus acidophilus, Lactobacillus kefiri, Lactobacillus fermentum, Lactobacillus brevis, Lactobacillus casei, Lactobacillus hilgardii, Lactobacillus lactis, Lactococcus spp, Leuconostoc spp. Water kefir also contains yeast species, often found in other vegetal fermentations, like in olives, chuckrut, beer or wine. The most important ones are Kluyveromyces spp, Debaryomyces hansenii, Candida kefyr, Dekkera anómala, Saccharomyces cerevisiae, Torulaspora delbrueckii, Pichia fermentans and Sacharomyces turicensis. The last biological contribution to the product is acetic bacteria, which are responsible to elaborate vinegar. Such species found in water kefir are Acetobacter favarum and Acetobacter orientalis.
Mentioned microorganisms interact between them and depend on one another. During the first steps of water kefir production some of them use the sugar of the mixture, and generate metabolites that others need. These second species, at the same time, produces metabolites usefull for the first ones. Actually water kefir complexity is such that is not known in detail the steps involved in the process, or the complexity of the final product. Water kefir is a drink with very low sugar; however it contains millions of bacteria in suspension and is enriched by their metabolites produced during the fermentation.
Along time, water kefir has been recommended to treat different illnesses such as: gastrointestinal disorders, allergies, ischemia or cardiovascular problems. Nevertheless, up to now, not enough studies have been carried out to prove a clear utility of water kefir on these health problems or compare different studies carried on.
Water kefir benefits are based on three factors: