Kefir a Fermented Milk Probiotic
~ January 1998 No.34 ~
The villagers of Caucasian mountains gave us yogurt. But this part of the world is also the origin of another fermented milk product that may be good for your health called kefir. The history of kefir is centuries old. It is very well known in eastern Europe. It is relatively new to North America, but there may be reason to get to know this fermented milk product better.
Like yogurt, kefir is milk based. The process to make kefir involves fermenting milk with what are called kefir grains. The grains are a mass of bacteria, yeast and polysaccharide. The grains are a living growing mass that have been the subject of much study to define exactly what makes up the grains. Origin, storage and handling all influence the make up of the grains. The microbiology of kefir grains is very complex. Among the yeasts Saccharomyces delbruecki, Saccharomyces cerevisiae have been identified and the bacteria Lactobacillus kefir and members of the Streptococcus generahave also been isolated in kefir grains. The polysaccharide that makes up the mass of the kefir grain has been shown to be unique and has been given the name kefiran. The fermentation process takes about twenty-four hours, during which the grains change milk into a thick, astringent tasting drink. Kefir is a probiotic because it contains live bacteria and yeast.
The Japanese have carried out a series of animal feeding trials that showed that kefir and kefir grains can slow down or reverse the growth of a wide variety of cancers. These studies are obviously a first step to proving that kefir may be beneficial against cancer. However, in each study reported, the development and spread of the cancers given to the mice was reduced. Other researchers have started to try to identify what component of the kefir grains may be responsible for its cancer fighting properties. At this time it is not clear whether it is the kefir itself , the bacteria or yeast or something that the bacteria produce that is / are the active agents.
It is clear that kefir has joined the list of food products that contain live bacteria that may have benefits that go beyond their basic nutritional value.