Thursday, March 23, 2017

The health-promoting and microbiota-modulating properties of the fermented beverage kefir

Abstract (as presented by the authors of the scientific work):

"Kefir is a complex fermented dairy product created through the symbiotic fermentation of milk by lactic acid bacteria and yeasts contained within an exopolysaccharide and protein complex called a kefir grain. As with other fermented dairy products, kefir has been associated with a range of health benefits such as cholesterol metabolism and angiotensin-converting enzyme (ACE) inhibition, antimicrobial activity, tumor suppression, increased speed of wound healing, and modulation of the immune system including the alleviation of allergy and asthma. These reports have led to increased interest in kefir as a focus of research and as a potential probiotic-containing product. Here, we review those studies with a particular emphasis on the microbial composition and the health benefits of the product, as well as discussing the further development of kefir as an important probiotic product."

Covered topics (the letter size corresponds to the frequency of mentioning in the text):

Conclusion (as presented by the authors of the scientific work):

"The purpose of this review has been to collate and summarize that which is known about the microbial composition of kefir and how this composition plays a role in the health benefits associated with kefir consumption. Kefir is a dynamic fermented dairy product with many different factors affecting the benefits associated with its consumption. These factors include the variable yeast and bacterial species present, as well as metabolites such as kefiran and other exopolysaccharides. While kefir has been associated with health benefits for 100s of years, the exact form of these benefits has, until recently, not been studied. The use of animal models and other in vitro analyses has allowed for the elucidation of how kefir positively impacts host health. Whole kefir, as well as specific fractions and individual organisms isolated from kefir, provide a multitude of positive effects when consumed. These range from improved cholesterol metabolism and wound healing, to the modulation of the immune system and microbiome, and even the potential alleviation of allergies and cancers. Further studies into the mechanisms behind these effects will allow scientists to better understand exactly how kefir and other fermented dairy products confer these benefits as well as how to harness these traits outside of kefir itself.

The wide range of potential health promoting effects of kefir could lead to a further expansion on the popularity of both traditional fermented kefir and products that are manufactured with kefir fractions or organisms. In order to fully exploit the beneficial characteristics of kefir, a more in-depth understanding of the composition of kefir is critical. With advances in metagenomic analysis through the development of high-throughput sequencing technology, this is a very realistic prospect. Armed with this knowledge, it should be possible to more readily isolate and examine the phenotypic characteristics of individual organisms present in a kefir blend while also providing a greater insight into the evolution of these organisms and how they became specialized to the kefir ecosystem. The additional knowledge gained can also provide crucial information relating to the mechanisms and exact agents responsible for beneficial effects that have been attributed to kefir (Atalan et al., 2003; Rodrigues et al., 2005; Huseini et al., 2012; Rahimzadeh et al., 2014).

The need for further research does not only apply to the mechanisms by which kefir consumption exerts these effects but also which organisms or parts of kefir are responsible for each benefit. By determining which organisms and metabolites are essential for each process, the possibility arises for the commercial manufacturing of kefir that is specifically designed to create the most profound effect in those that consume it. As it stands currently, the highly variable nature of the organisms and metabolites present in traditional kefir requires health claims to be verified individually in each grain and kefir beverage. The ability to combine the best possible strains of the best organisms from multiple sources of kefir would create the potential for greater benefits than have been previously observed, with a measure of control over these effects that has not been possible in traditional kefir."

Full-text access of the referenced scientific work:

Bourrie BC, Willing BP, Cotter PD. The Microbiota and Health Promoting
Characteristics of the Fermented Beverage Kefir. Front Microbiol. 2016 May
4;7:647. doi: 10.3389/fmicb.2016.00647. Review. PubMed PMID: 27199969; PubMed
Central PMCID: PMC4854945.


  1. I have had kefir water, in these studies are the subjects eating the grain itself?

    1. Good point - it seems that most of the in vivo studies were done with kefir grain suppementation