Kefir is well documented for it wide range of health benefits and dates back 5000+ years.  Kefir comes two different options: a vegan culture as well as a dairy culture. You cannot convert either culture to the other. These are two distinctly different cultures.  The vegan water kefir option makes beautiful soda like fermented beverages.  Milk kefir makes a cream drinking yogurt fermented beverage that can be flavour as well as turned into yogurts, butters and cheeses.