If someone suggests something is a cure all for everyone, and a doctor says that cure all is killing someone, and there's medical research backing up the doctor

If someone suggests something is a cure all for everyone, and a doctor says that cure all is killing someone, and there's medical research backing up the doctor - I'm going to trust the doctor. My N=1 anecdote is a counterexample that has medical research to back it up. Or are you discrediting the person's anecdote about a carnivorous diet being healthy?