We make the protein smoothie drinks with Kifer Milk which is a probiotic which will have the "GI" it also is a sulphur protein which we use instead of the cottage cheese for the Dr. Budwig diet.
Go to http://www.Livesuperfoods.com and look up probiotics and read about EM concentrate. I haven't done this yet but you can make a super liquid vitamin/antioxidant probiotic type of drink! A product already made is Fervita which I haven't tried yet but have ordered the EM to make our own. This would be a good drink for your brother