Two suggestions i can make are:
1) The next time she lectures you, ask her where she heard it from. Ask to see the website/ scientific study. Dont be arrogant with her in your questioning, because she will most likely go into defence mode, and you wont make any ground on the subject.
2) Stop bringing it up with her. it sounds as if you like to share your hobby with her, which makes sence. you should be able to talk to your spouse about your interests. But if she is stubborn, then maybe you should tell her that whether she agrees with it or not, the supps are safe and affordable, and just stop talking to her about it.
Hope that helps a bit, and just out of curiosity, what kind of things does she say to you?
My brother has always been adamant that creatine is an anabolic steroid... A long time ago I stopped trying to change his mind on the matter.