The discovery could inspire the development of new ways to tackle antibiotic resistant bacteria. People may have been producing and drinking kefir, a fermented milk drink that originated in Tibet and the North Caucasus, for thousands of years. People can make the sour, slightly effervescent brew by infusing milk with kefir grains, which are a starchy matrix containing a symbiotic community of lactic acid bacteria, acetic bacteria, and yeasts. The drink has many reputed health benefits, which include lowering cholesterol, reducing inflammation, and exerting an antioxidant effect. In common with other probiotics, kefir also has antimicrobial properties. However, scientists were unsure exactly how it inhibits the growth of disease-causing bacteria.