I dont know if milk kefir its good for leaky gut (if you have some kind of adrenal fatigue, candida etc you will have some degree of gut permeability) and the fructose content of water kefir made me dump it. I think the poor grains were dying anyway. I liked the raw goat milk kefir a lot more, the grains grew rapidly, it tastes pretty addictive and made me go to the bathroom from the first time which water kefir didnt. I think im addicted to dairy because of food allergies . The contain in casein of milk kefir was a no brainer for a leaky gut asperger guy.
Plus all fermented foods are high in histamine which can be an issue for us.