Kefir changes the intestinal and oral microflora

Modern kefir production has retained the basic principle, but has introduced many variations. Different types of milk are used, grain proportions, fermentation duration and temperature conditions change. It is this variability that poses a serious problem for science. The composition of microorganisms in the finished drink can vary significantly, and with it the potential effects on the human body.

The authors of the review emphasize that lactic acid bacteria such as

• Lentilactobacillus kefiri
• Leuconostoc mesenteroides
• Lactococcus lactis

play a key role in fermentation. They process lactose, produce lactic acid and a number of biologically active compounds capable of suppressing the growth of pathogenic microorganisms. Some of these bacteria are able to survive when passing through the gastrointestinal tract and temporarily gain a foothold on the intestinal mucosa, which is considered an important sign of probiotic potential.

Of particular interest is the presence of acetic acid bacteria and yeast. The former are involved in maintaining intestinal epithelial balance and affect motility, the latter form the characteristic taste of the drink and produce substances with possible anti-inflammatory and antimicrobial properties. A number of works mention the strain Saccharomyces cerevisiae var. boulardii, which is being studied in the context of irritable bowel syndrome and inflammatory diseases of the gastrointestinal tract.

When researchers move from theory to clinical data, the picture becomes heterogeneous. In some groups of healthy people, changes in the microbiota after consuming kefir were minimal and statistically insignificant. Patients with metabolic syndrome, inflammatory bowel disease, or polycystic ovary syndrome showed more pronounced changes, including the growth of individual bacterial classes and improvements in some metabolic and psycho-emotional parameters. In intensive care units, kefir was associated with an improvement in the integral indices of the state of the microbiome, even with a decrease in its diversity.

The oral cavity has been studied much worse. A small number of studies indicate a decrease in the number of Streptococcus mutans, a bacterium associated with the development of caries in both children and adults. At the same time, all available studies were based on cultural methods that reflect only a small part of the microbial community.

The authors of the review are extremely careful in their final conclusions. Kefir can affect the gut and oral microbiome, but the extent of this effect, its stability and clinical significance are still unclear. The heterogeneity of products, small samples, and differences in research design do not allow us to draw unambiguous conclusions about the long-term health benefits of kefir. But scientists agree on one thing: you can still include kefir in your diet several times a week to try to improve your microflora and condition.