Dietary influence of kefir on microbial activities in the mouse bowel


Domingo Marquina Department of Microbiology III, Biology Faculty, Complutense University of Madrid, 28040 Madrid, Spain (e-mail:


Aims: In this work the microflora present in kefir, a fermented milk product, was studied together with the effect of kefir administration on different groups of indigenous bacteria of mouse bowel.

Methods and Results: Kefir microflora was composed of lactic acid bacteria, acetic acid bacteria and yeasts. Yeast population was composed of Saccharomyces cerevisiae, S. unisporus, Candida kefir, Kluyveromyces marxianus and K. lactis. The streptococci levels in kefir treated mice increased by 10-fold and the levels of sulfite-reducing clostridia decreased by 100-fold. The number of lactic acid bacteria increased significantly.

Conclusions: The administration of kefir significantly increased the lactic acid bacteria counts in the mucosa of the bowel. Ingestion of kefir specifically lowered microbial populations of Enterobacteriaceae and clostridia.

Significance and Impact of the Study: This is the first long-term study about the effects of the kefir administration on the intestinal microflora of mice.