>>212204369 (OP)This is better than milk, even better is making your own kefir. This store kefir is typically made using weaker powdered kefir grains to ferment.
All you have to do to make kefir is put some milk and kefir grains in a bottle with a little cheese cloth lid and after a day you get kefir. You strain out the grains and make another batch.
They multiply on their own in the milk and so it is self sustaining. The homemade stuff is much better for you and doesn’t have all the added sugar from the store bought. Still it is best blended with fruit to make a smoothie like that. Probably the easiest thing to make although eventually you will have too much kefir grain, in which case you will need to find another kefir maker to offload to or just trash it. You can also refrigerate or freeze them I believe to slow it down but I’m not sure on the specifics of that