Potential Characteristics of Water Kefir on Health Benefits

Water kefir is a non-dairy fermented beverage that has received increasing scientific attention due to its complex microbial composition and its suitability for individuals with dietary restrictions. This review critically examines the current body of scientific evidence addressing the functional properties and potential health-related effects of water kefir. A systematic literature search was conducted using the PubMed and Scopus databases, focusing on studies published over the past decade. Experimental evidence derived from in vitro assays and in vivo studies in animal models suggests that water kefir and its derived components may exhibit antioxidant, anti-inflammatory, antibacterial, detoxifying, and gut microbiota-modulating activities. Several studies have also reported probiotic-related characteristics among microorganisms isolated from water kefir, as well as beneficial effects in experimental models of chronic conditions, including type 2 diabetes, colitis, and liver injury. Reported microbiota-associated effects include increased bacterial diversity, enrichment of beneficial genera such as Lactobacillus spp. and Bifidobacterium spp., and reductions in potentially pathogenic taxa including Escherichia spp. and Shigella spp. Nevertheless, the available evidence is largely preclinical, and substantial variability in microbial composition, fermentation conditions, and experimental design limits direct comparison across studies. Well-designed human clinical trials are therefore required to validate these findings, establish efficacy and safety, and clarify the relevance of water kefir as a functional fermented food in human health.