Whey protein powder is considered to best for long-term sourcing of the amino acid cysteine for purposes of supplementing glutathione.
But if you mix whey powder in a high speed blender, the structure of the protein is disrupted. This ability to souce cysteine is probably reduced. That is because the cysteine in whey is in the form of cystine, which is a sort of double cyteine molecule. This high cystine content is what gives whey protein its unique ability to increase glutathione. But cystine is easily broken down by vigorous mechanical action such as mixing in a high speed blender.
Protein Blend
So how do you get that creamy, lump-free, milkshake texture without vigorous mixing? It just takes some extra time, that's all. Measure out a suitable amount of powder into a 12 oz. glass or cup. Fill about half way with skim milk. (You can use almost any drink, but whey has a mild milky taste. Personally, I don't care much for it when mixed with orange juice.)
Stir gently with a fork. Scrape the bottom and the sides to get all the powder hydrated. Let it set about 20 minutes occasionally mixing every 5 to 10 minutes. At the end of 20 minutes, fill the rest of the way.
Any lumps will swell and disperse in this time. There may be a few small lumps sitting on the surface at the end of 20 minutes. If you are really finicky, you can pick them out with the tip of a spoon. I usually keep the glass in the refrigerator during this time only because the cat seems to take a great deal of interest in these proceedings and I don't want to leave the glass out, unattended while I go off and do other things during the 20 minutes.