We have started making our own kefir fermented milk products. Kefir originated when shepherds discovered that milk carried in leather pouches would ferment and produce a fermented beverage which has a pleasing taste, once your are accustomed to it.
We were given a starter culture and the procedure is you add milk to the kefir grains and allow it to ferment for 24 hours at room temperature. A tablespoon of the kefir grains is adequate for 8 ozs of milk. After 24 hours the grains have converted the lactose in the milk to lactic acid. You strain off the product and it contains probiotic bacteria and fungi which are great for GI health. You return to your jar the residue in the strainer and top it up with fresh milk and 24 hours later you have more kefir. You can blend the kefir with frozen blueberries or strawberries and add some honey to produce a smoothie.
Initially we added the kefir starter grains to 1% conventional milk and they were unhappy and refused to do their magic dance. We do not have easy access to raw milk and besides we (currently) have little use for the fat/cream which comes with the milk. We do not usually use organic milk. but on an inspiration we switched to 1% organic milk and the kefir is thriving.
So when studies are done on the benefits of organic produce and focus only on nutritional content, they are overlooking possible components such as anti-biotics in conventional milk. The question is whether these overlooked components affect not only the bacteria in kefir but the bacteria in our GI tract and therefore our health.