Can anybody help?

Hello, everyone! I have a friend who says that whenever he takes protein powder for 2 weeks, he gets small lesions on his tongue. I’ve never head of protein causing anything of the sort, so I am not convinced it’s protein. Sounds like some kind of deficiency to me. Does anyone have ideas regarding what that could be? Thanks in advance.

My guess is that it is canker sores he is getting. Is he drinking or eating alot of acidic fruit, such as oranges, grapefruit, or lemon? If anything, the increased protein and amino acids should help REDUCE these sores.