Kefir is a natural effervescence, producing gas; that's why they package it into a PET bottle. Shake gently before opening. Kefir is a world champion health product. There are many health benefits and just one tablespoon provides billions of live microrganisms. Fermented goat milk with beneficial probiotics that contribute to healthy intestinal flora. No sugar, additives, milk protiens, artifical or natural flavours added. Lactose and gluten free. Made locally in B.C. Contains 10 active cultures and more than 1 billion probiotics per serving (per 250ml). Kefir is called the drink of the centenarians.