Is it bad to take vitamins and supplements a lot?

I'm 16. I have high blood pressure and risk of heart disease that runs in the family. Because of that, I take Cranberry, Garlic, and Omega 3. Also, I take Tart Black Cherry as a antioxidant and Calcium with Vitamin D for bones. I also take a multivitamin if I think I haven't gotten enough vitamins through my diet. I've always this this was a good thing. Now people are saying things like "You're going to kill your kidney if you don't stop". Is it really as bad as people say?