KEFIRAN
Presently, the complete mechanism involved in the construction of the bio-matrix [kefir grains], is not well understood at a scientific level, although there is an increase interest in this area. A unique soluble gel-polysaccharide [PS] discovered in kefir grains was given the name, kefiran [KGF-C]. Cultured in milk, the PS is produced at the centre of the grain, where anaerobic conditions are favourable for kefiran synthesis in the presence of ethanol alcohol.[2] Kefiran is synthesized by encapsulated homo-fermentative Lactobacilli species including Lb. kefiranofaciens subsp. kefirgranum subsp. nov and Lb. kefiri. By weight, dry kefir grains consist of some 45% kefiran. The PS is composed of two mono-saccharides; D-glucose and D-galactose in equal proportions. The proposed molecular structure of kefiran is a branched hexa- or hepta-saccharide repeating unit, which in itself is composed of a regular pentasaccharide unit, to which one or two sugar residues are randomly linked [9].
Chair form diagram of the proposed molecular structure of kefiran. The variety of linkage types of the molecule may account for the rather poor accessibility of kefiran to enzymic attack [2a], which is possibly why the PS is reasonably inert to digestive enzymes. This property might be important in the ecological stability of the kefir grain, including the therapeutic activity of kefiran, due to the PS remaining chemically stable through the process of digestion.
There are other strains of Lactobacilli capable of producing a similar type of PS, Lb. sp. KPB-167B is one such organism. This, including other species of Lactobacilli, which produce either kefiran or a similar form of PS [with slight variations between glucose and galactose ratio, different molecular weights including variations in the optical rotation of the molecule] produced at a variable rate, or, the amount of, may be mechanisms involved in the natural tendency for each grain to propagate as a self-enclosed body. This is possibly because of different strains, or type-strains of encapsulated organisms included among yeasts, arranged at specific locations as layers or branches throughout the matrix. Stress factors due to culture-conditions or the structural makeup of the matrix itself, may incur the same strain of encapsulated organism to produce either variable amounts of kefiran, or a variation of the polysaccharide.
Experiments performed with mice [against mice really, if you think about it], revealed kefiran exhibited anti-tumour properties. In these experiments, orally administered kefiran was found to reduce the size of tumours, by inducing a specific immune response in mice. Much of this early research was performed in Japan.[3-6] Recent research evaluated kefir grains induced a systemic anti-inflammatory response in kefir-grain fed rats.[7] The author [Dominic Anfiteatro] initially discovered the anti-inflammatory property of milk kefir-grains, through the implementation of rectal injections [implants] and retention including the ingestion of adequate amount of kefir grains to successfully correct Ulcerative Colitis in his case [1999]. The anti-inflammatory effect was later investigated and correlated scientifically by Prof. Jose M. Schneedorf et. al. [2003].
More recently, the author observed that with the ingestion of 1/3 cup of kefir grains taken daily over 7 days, benefited 3 cases [one being the author] where the individuals suffered from pain associated with Repetitive Strain Injury [RSI] of the right arm, due to excessive use of a computer keyboard and mouse-clicking over some years. These latter findings further suggest the systemic anti-inflammatory property of kefir-grain kefiran. Quite possibly kefiran activity in conjunction with organisms of the grain, encourage a systemic benefit via multiple components or vehicles.
A study on the effects of kefiran in laboratory rats demonstrated that kefiran can significantly suppress increased blood pressure and reduced the serum cholesterol levels in SHRSP/Hos rats, when subjects consumed excessive dietary cholesterol. The study also explains kefiran supplementation had the ability to significantly lower blood glucose in KKAy mice. In addition, the administration of kefiran in constipated SD rats caused an obvious improvement in the levels of faecal moisture and wet weights of faeces [8-10].
The combination of all the above, suggests that kefiran, and in fact kefir grains are useful as functional food to prevent or control some common occurring diseases. This further reinforces what the author has suggested for many years, that the regular ingestion of kefir grains, should be considered of greater, practical importance and especially appreciated by individuals preparing traditional kefir.
As and end note, kefiran is also useful as a natural gelling agent, for thickening food. The author explains many examples of the possible use of kefir grain kefiran in the preparation of wonderful textured baked goods such as wholemeal sourdough bread, cakes, pretzels and pastry. For ice-cream making, thickening yogurt and more.
2. Arihara K, Tobo T,
Adachi S. Int J Food Microbiol [1990];11:127-34. Immunofluorescence microscopic
studies on distribution of L. kefiranofaciens and L. kefir in kefir grains.
2a. Kooiman, P. Carbohydrate Research. [1968]; 7[2]: 200-211. The chemical structure of kefiran, the water-soluble polysaccharide of the kefir grain.
3. Murofushi M, Mizuguchi J, Aibara K, Matuhasi T, et al. Immunopharmacology
[1986] Aug;121:29-35. Immunopotentiative effect of polysaccharide from kefir
grain, KGF-C, administered orally in mice.
4. Yakugaku Zasshi [1992] Jul;112:489-95. Pharmacological study on kefir-a
fermented milk product in Caucasus. I. On antitumor activity (1). Kubo M,
Odani T, Nakamura S, Tokumaru S, Matsuda H, et al. Faculty of Pharmaceutical
Sciences, Kinki University, Osaka, Japan.
5. Shiomi M, Sasaki K, Murofushi M, Aibara K, et al. Jpn J Med Sci Biol
[1982] Apr;35:75-80. Antitumor activity in mice of orally administered polysaccharide
from Kefir grain.
6. Shiomi M, Aibara K, Murofushi M, et al. Jpn J Med Sci Biol [1983] Feb;36:49- 53. Effect of orally administered polysaccharide from kefir grain on delayed-type hypersensitivity and tumor growth in mice.
7. Schneedorf M., Anfiteatro D. [2004] Fitoterapicos Anti-inflamatorios by Carvalho, J.C.T. Quefir, um probiotico produzido por microorganismos encapsulados e inflamacao. Chapter 33 pp 443-462. / Diniz R . O, Garla L . K, Schneedorf M., Carvalho J.C.T. [Jan. 2003] Study of anti-inflammatory activity of Tibetan mushroom, a symbiotic culture of bacteria and fungi encapsulated into a polysaccharide matrix. Pharmacol Res; 47[1]:49-52
8. Maeda H, Zhu X, Omura K, Suzuki S, Kitamura S. [2004] Effects of an exopolysaccharide (kefiran) on lipids, blood pressure, blood glucose, and constipation. Biofactors. 2004;22(1- 4):197-200 / H. Maeda, X. Zhu, S. Suzuki, S. Kitamura [June 8-10/2003] Physiological effects of an exopolysaccharide produced by lactobacillus kefiranofaciens [International Symposium on Polysaccharide Engineering 2003].
9. H. Maeda, X. Zhu, S. Suzuki, K. Suzuki, S. Kitamura [June 2004]. Structural Characterization and Biological Activities of an Exopolysaccharide Kefiran Produced by Lactobacillus kefiranofaciens WT-2B. [J of Agri and Food Chem].
10. H. Maeda, H. Mizumoto, M. Suzuki, K. Tsuji [Jan 5/2005] Effects of Kefiran-Feeding on Fecal Cholesterol Excretion, Hepatic Injury and Intestinal Histamine Concentration in Rats [BioFactors 22].