I have not heard of acidophils milk. I know it is in yogurt. My son actually takes acidophilus but in powder form from the health food store. Since he is on the gf/cf diet milk and yogurt are out of the question.
We work very closely with a nutritionalist who recommends rotating diferent strains of yeast. We currently rotate acidophilus, Saccharomyces boulardii and Pro Bio Gold. This is to help eliminate bad yeast from his gut.
I buy that kind of milk sometimes for my husband and I, however, there is casins in it, which is not good for most kids with autism so if your son is on the gf/cf diet, then it's not good for him.
my daughter is having bowel problems and i have tried soy lactose free milk but it makes it worse. since she has been on this milk the ruuny poop has gotten a little better.
acidophilus milk 
Linear Mode
