My son had his wisdom teeth out this morning. Asked the DDS about why no protein powder 1 week before the procedure and he said:
"I am concerned with the effect it has on the kidneys and there might be something in the protein powder, something not natural, that during the procedure would cause problems such as the blood not being able to clot. You really don't know what they put in the product."
From what I have read in PPST 3rd edition and the information/links on the boards here, I feel that his statement about the kidneys is not true. I suppose he is referring to getting a "bad batch" of protein powder and the blood not being able to clot. My son and I have not had any problems over the last 3 years.
FWIW we use Now Whey Protein Isolate.