Adverse effects of kefir consumption
Pro Research Analysisby 
Searched over 200M research papers
Kefir Consumption and Adverse Effects: Overview
Kefir is a fermented dairy beverage known for its probiotic content and potential health benefits. While many studies highlight its positive effects, it is important to consider possible adverse effects or risks associated with its consumption.
General Safety and Health Benefits of Kefir
Most research on kefir consumption in humans and animals reports beneficial effects, such as improved gut microbiota, reduced inflammation, and better metabolic parameters. Studies in patients with inflammatory bowel disease and metabolic syndrome found that kefir improved gut microbiota composition and reduced some symptoms, with no significant adverse effects reported during the study periods 35. Similarly, in hypertensive individuals, regular kefir consumption led to reduced systolic blood pressure and weight control, again without notable negative outcomes . In healthy women, kefir did not increase IGF-1 levels beyond normal ranges, suggesting no immediate risk of promoting carcinogenesis in this context .
Potential Adverse Effects in Specific Contexts
Increased Risk During Acute Infections
A notable exception to kefir’s generally safe profile was observed in a study involving mice infected with Salmonella Typhimurium. In this case, daily kefir consumption before infection altered the immune response and gut microbiota in a way that actually increased mortality and worsened the infection’s severity. The study suggests that kefir may facilitate the systemic spread of pathogens during acute infections, likely by reducing intestinal inflammation and altering immune signaling, which can favor pathogen replication and translocation . This finding highlights the need for caution when consuming kefir or other probiotics during acute gastrointestinal infections.
Lack of Adverse Effects in Other Populations
In studies involving obese mice, kefir consumption was associated with reduced body weight, improved liver health, and lower inflammation, with no adverse effects reported . Similarly, in studies on metabolic syndrome and hypertensive patients, kefir did not negatively impact blood or kidney parameters, nor did it cause significant changes in lipid profiles or glycemic control compared to controls 457. In lactating mothers, kefir altered the carbohydrate profile of breast milk but did not report any negative health outcomes for mothers or infants .
Considerations for Special Populations
While kefir is generally well-tolerated, individuals with compromised immune systems, those with acute infections, or those with specific allergies (such as dairy allergies) should consult healthcare professionals before consuming kefir. The evidence suggests that, outside of acute infection scenarios, kefir does not commonly cause adverse effects in healthy or chronically ill populations 1345+3 MORE.
Conclusion
Kefir is widely regarded as safe and beneficial for most people, with studies showing improvements in gut health, inflammation, and metabolic parameters. However, caution is warranted during acute infections, as kefir may worsen outcomes by altering immune responses and gut microbiota. For the general population, adverse effects are rare, but individuals with specific health conditions should seek medical advice before regular consumption.
Sources and full results
Most relevant research papers on this topic
Daily Intake of Household-Produced Milk Kefir on Salmonella Typhimurium Infection in C57BL/6 Mice: Mortality, Microbiota Modulation and Immunological Implications.
Daily consumption of milk kefir may not be enough to combat acute Salmonella Typhimurium infections and may worsen the prognosis, leaving the intestine less inflamed, favoring pathogen replication and translocation.
Effect of administering kefir on the changes in fecal microbiota and symptoms of inflammatory bowel disease: A randomized controlled trial.
Kefir consumption may improve gut microbiota and enhance the quality of life for patients with inflammatory bowel disease in the short term.
DOI