How much kefir should you have per day? We recommend starting slowly, so increase your kefir intake gradually otherwise you may get an upset stomach.Initially limit your intake to 1 Cup a day. Related articles How long can kefir be stored in the fridge? Kefir - reculturing, culture and grains Can I add lemon to my kefir? What are the essential elements of making Kefir? Is the metal ball in the kefir kit okay to use?