Water Kefir Grains and Milk Kefir Grains are both powerful sources of probiotics, but they're fermented in different mediums. While Milk Kefir Grains require dairy or nut-based milk, Water Kefir Grains thrive in a sugar-water solution. They also offer a dairy-free alternative for those who are lactose intolerant or vegan. The probiotic profile might differ slightly, but both are superb choices for boosting gut health.