The Effects of Kefir on the Human Oral and Gut Microbiome

Kefir, a fermented probiotic drink made from milk, water, or plant-based ingredients, has gained significant attention as a dietary supplement. Originating from the Caucasus Mountains over three thousand years ago, kefir is believed to harbor a range of health benefits through its ability to alter the composition of microbial niches within the human body. These microbial niches are called microbiomes and encompass the collective community of microbial organisms, their genomes and environment. The modern commercialization of kefir has driven the need for high-quality research into its impact on the human microbiome and associated health outcomes; however, there is currently very limited scientific evidence supporting effects of kefir consumption on the human oral and gut microbiome. High-quality human clinical trials are essential to establish the safety and effectiveness of kefir before it can be advised for use in treating conditions linked to the oral and gut microbiota or metabolic health. This literature review aims to critically analyze recent studies investigating the effect of kefir consumption on the oral and gut microbiome, as well as its potential implications for human health. By examining kefir's effects on these interconnected microbial ecosystems, we can better understand its potential and limitations as a functional food for promoting systemic health.