Anti-inflammatory pathways of kefir in murine model: a systematic review

Abstract Context Kefir consumption has been associated with immune response modulation, antioxidant, and anti-inflammatory effects. Objective The objective of this systematic review was to investigate the role of kefir against inflammation and the main response mechanisms involved in this process in a murine model. Data Sources The searches were searched in the PubMed, Science Direct, and LILACS databases. Only murine model studies, according to PRISMA guidelines, published in the past 10 years were included. Study Selection Only articles about original and placebo-controlled experiments in murine models used to investigate the anti-inflammatory mechanisms of kefir were considered. Of the articles found, 349 were excluded according to the following criteria: duplicate articles (n = 99), off-topic title and abstract (n = 157), reviews (n = 47), studies in vitro (n = 29), and studies with humans (n = 17). In total, 23 studies were included in this review. Data Extraction Two independently working authors assessed the risk of bias and extracted data from the included studies. Results Kefir consumption had positive effects on inflammation modulation. The main mechanisms involved were the reduction of pro-inflammatory and molecular markers; reduction in inflammatory infiltrate in tissues, serum biomarkers, risk factors for chronic diseases, and parasitic infection; composition and metabolic activity change of intestinal microbiota and mycobiota; activation of humoral and cellular immunity; and modulation of oxidative stress. Conclusions Kefir modulates the immune system in different experimental models, among other secondary outcomes, to improve overall health. The beverage reduces inflammation through the alternation between innate, Th1, and Th2 responses, reducing levels of pro-inflammatory cytokines while increasing those of anti-inflammatory ones. In addition, it also mediates immunomodulatory and protective effects through the numerous molecular biomarkers and organic acids produced and secreted by kefir in the intestinal microbiota. The health-promoting effects attributed to kefir may help in the different treatments of inflammatory, chronic, and infectious diseases in the population.