What to remember :
Contains natural probiotics that promote microbiota balance.
A digestive ally that supports intestinal flora.
Support for immunity by modulating inflammation.
A metabolic asset for blood sugar and cholesterol.
Antimicrobial effects against certain pathogens.
What is kefir?
Kefir is a slightly sparkling and tangy drink made by fermenting kefir grains in a chosen beverage: milk or sweetened water with the addition of fresh fruit and/or dried fruit to give it a pleasant taste. There are therefore two types of kefir: milk kefir and fruit kefir.
The kefir grains used contain various microorganisms including yeasts and lactic acid bacteria. Upon contact with the liquid and in a suitable environment (nutrients, temperature and adequate storage conditions, etc.), these grains release microorganisms which, thanks to the sugar present in the environment, will multiply and ferment, that is to say, transform this sugar into alcohol, carbon dioxide and lactic acid. 48 hours after the start of fermentation, we then obtain the characteristics of this drink: sparkling, sweet, slightly acidic and rich in probiotic microorganisms (living microorganisms that contribute to the balance of the intestinal microbiota).
Furthermore, although alcohol is produced, it is found in very small quantities in the final drink: it does not exceed 1%, which is a negligible quantity for healthy people (without any particular health problems). However, kefir is not recommended for pregnant and breastfeeding women and people suffering from liver disorders.
This makes it an interesting drink, similar to kombucha , which goes perfectly with summer aperitifs or even as a change from classic drinks such as sodas, water syrups, fruit juices and alcoholic drinks that can be consumed regularly.
NB: Milk kefir, despite the presence of probiotics, is generally not suitable for people who are lactose intolerant or allergic to milk proteins, or for vegans.
The benefits of kefir
#1 - Digestive health and microbiota
Kefir is, as we have seen previously, a natural source of probiotics. According to a study published in Nutrients , regular consumption of kefir promotes the growth of beneficial bacteria such as Lactobacillus and Bifidobacterium , while limiting the proliferation of pathogens.
By promoting a healthy microbiota, kefir can improve digestion and modulate certain gastrointestinal conditions.
A study published in Oxidative Medicine and Cellular Longevity highlights its potential to restore intestinal flora after antibiotic therapy and its ability to positively influence intestinal microbial composition. However, specific effects on conditions such as irritable bowel syndrome (IBS) require further clinical studies.
#2 - Immune system and inflammation
Kefir exerts a modulating effect on the immune system thanks to the probiotics and metabolites it contains. According to a study published in Cureus , microorganisms present in kefir can influence the immune response by modulating the expression of pro- and anti-inflammatory cytokines. This modulation could play a key role in regulating chronic inflammation .
Additionally, some kefir-specific bacterial strains, such as Lactobacillus kefiri , have demonstrated an ability to inhibit the production of inflammatory mediators and promote the adaptive immune response. These effects could have interesting implications for the prevention and management of chronic inflammatory diseases, although further clinical studies are needed to confirm these observations.
#3 - Metabolic effects (cholesterol, blood sugar, cardiovascular health)
Kefir may have beneficial effects on metabolism by reducing markers of inflammation and improving cardiovascular parameters. A study published in Foods indicates that its regular consumption is associated with a reduction in LDL cholesterol (“bad” cholesterol) and an increase in HDL (“good” cholesterol), thus reducing cardiovascular risks.
Kefir also appears to have a beneficial effect on blood sugar management. Some research suggests it may improve insulin sensitivity and reduce the risk of type 2 diabetes. The underlying mechanisms are thought to involve the action of probiotics on glucose metabolism and the reduction of systemic inflammation.
#4 - Antimicrobial properties
Kefir also has antimicrobial properties due to the production of bioactive substances such as bacteriocins and organic acids. These compounds can inhibit the growth of pathogens such as Escherichia coli, Salmonella and Helicobacter pylori , thus helping to protect against certain gastrointestinal infections.
However, it is important to emphasize that the majority of these results come from laboratory experiments and that their translation to clinical applications in humans requires additional research. The effectiveness of kefir remains a promising subject of study, but still needs to be further investigated.
Conclusion
Kefir, a drink that has been around for thousands of years, is gradually making a comeback in our modern societies, and this is no coincidence. Indeed, as we have seen, it constitutes a broad subject of research on various aspects: digestive health and microbiota, immune system and inflammation, metabolic effects, antimicrobial properties, etc.
Research is not about to stop and could give us hope for clinical studies on humans. In the meantime, don't delay in consuming this drink with a thousand and one virtues by starting with a small amount a few times a week and gradually increasing to a large glass per day. Enjoy!
Sources :
[1] National Museum of Natural History, consulted from: https://www.mnhn.fr/fr/qu-est-ce-que-le-kefir-et-d-ou-vient-il
[2] Farag, MA, Jomaa, SA, Abd El-Wahed, A., & R. El-Seedi, H. (2020). The Many Faces of Kefir Fermented Dairy Products: Quality Characteristics, Flavor Chemistry, Nutritional Value, Health Benefits, and Safety. Nutrients, 12(2), 346. https://doi.org/10.3390/nu12020346
[3] Vieira, CP, Rosario, AILS, Lelis, CA, Rekowsky, BSS, Carvalho, APA, Rosário, DKA, Elias, TA, Costa, MP, Foguel, D., & Conte-Junior, CA (2021). Bioactive Compounds from Kefir and Their Potential Benefits on Health: A Systematic Review and Meta-Analysis. Oxidative medicine and cellular longevity, 2021, 9081738. https://doi.org/10.1155/2021/9081738
[4] Culpepper T. (2022). The Effects of Kefir and Kefir Components on Immune and Metabolic Physiology in Pre-Clinical Studies: A Narrative Review. Cureus, 14(8), e27768. https://doi.org/10.7759/cureus.27768
[5] Azizi, NF, Kumar, MR, Yeap, SK, Abdullah, JO, Khalid, M., Omar, AR, Osman, MA, Mortadza, SAS, & Alitheen, NB (2021). Kefir and Its Biological Activities. Foods (Basel, Switzerland), 10(6), 1210. https://doi.org/10.3390/foods10061210
