The Caucasus of the former Soviet Union, where kefir was originated, is one of the world's top longevity regions. People in this region regularly eat fermented milk and cheese made from goat milk. A typical example of such fermented milk is kefir, which is a famous longevity food. Kefir is consumed mostly in the former Soviet Union and Eastern Europe. In spite of its potential, kefir has little profile in Japan or other parts of the world.

One reason of this limited diffusion is the fact that the export of kefir grain, the starter of fermentation, from the area of the origin is restricted. Another reason is that kefir contains carbon dioxide gas and a small amount of alcohol resulted by co-occurring alcohol fermentation in the production process. The gas generation causes problems in terms of product containers for distribution. Moreover, Japanese people tend to be reluctant to give alcoholic beverages to children, even in a minute amount.

Another reason is a matter of preference. The sense of taste is unexpectedly conservative; people's preference is greatly effected by the taste they were familiar in their early age. Therefore, as loved in the certain area in Europe and very good for health maintenance as it may be, kefir cannot be incorporated easily into the diet in other areas. When a foreign food is brought to Japan, it is necessary to change it to fit the Japanese taste.

In order to improve the taste and enhance the functionality of kefir, a new functional food ingredient derived from kefir was developed for promotion in Japan and other parts of the world. The product is called “Rice Kefiran.”

The functionality of kefir is thought mostly due to a type of lactobacillus called Lactobacillus Kefiranofaciens - named by Japanese scientists, Dr. Tomotari Mitsuoka et al. -, which is a part of kefir grain. Lactobacillus Kefiranofaciens was isolated. This lactobacillus produces a viscous polysaccharide called kefiran, which is the source of the advantages of kefir as health food. Lactobacillus Kefiranofaciens itself is a homofermenter that generates no alcohol or carbon dioxide gas.

Lactic fermentation technique solely with Lactobacillus Kefiranofaciens was targeted in order to make up for kefir's shortcomings and strengthen its functionality. However, mass cultivation of this lactobacillus was difficult, and its fermentation process was troublesome. Consequently, there was yet to be any successful cases. A breakthrough was finally achieved by switching the culture medium from conventional “milk” to “rice,” a staple food for the Japanese. Finally, a technique for stable production of Rice Kefiran that is a vegetable food ingredient with high content of kefiran was established.

Because Rice Kefiran is water-soluble, non-digestible polysaccharide, a kind of dietary fiber, has the attributes associated with water-soluble dietary fiber. Some of such well-known functions include the improvement of the intestinal environment, the lowering of blood lipid levels, the control of blood glucose levels, and the suppression of hypertension. Although substantial parts of the functionality of Rice Kefiran and kefir are overlapping with that of dietary fiber, kefiran characteristically shows its effect at lower doses than water-soluble fiber.

It remains unclear, however, whether this characteristics is caused by kefiran's molecular structure or by its physical property such as its viscosity.

As for cholesterol absorption inhibition, it has been observed that kefiran has a function for preventing esterification, which ordinary dietary fiber does not have. In addition, as for improvement of the intestinal environment, kefiran directly acts on bowel movement, and Lactobacillus Kefiranofaciens is thought to produce a kind of peptide with antibacterial activity and to control the intestinal flora.