No, blenders do not destroy protein powder. This is like saying a blender will destroy water into oxygen and hydrogen. Quite impossible, eh!
Protein powder is simpy a protein rich food just like egg, meat, chicken, etc.
Protein powder are “destroyed” by the processes of denaturation or by breaking down into amino acids.
High temperature, acidity, or other chemical activity can denature the structure and properties of proteins.
Naturally, proteins are coiled helix structures and have their biological activity. When exposed to chemical or physical change, protein powder loose their activity and uncoil the helix structure. This is when we say the proteins are destroyed or denatured.
Our body destroy proteins and break them into components called amino acids. These amino acids are the nutrition that we get from proteins.
Is it okay to blend protein powder?
Yes perfectly, mechanical shaking of protein by blenders does not do any of the above. Neither does a blender denatures protein nor it can destroy the protein powder.
Even if it could, possibly destroy the proteins into amino acids. It could be a good thing. These broken components would be easy to digest.
You can use almost any blender to blend protein powder without changing its nutrititonal value.