Supplement makers aren't allowed to say their product diagnoses, treats, cures, reduces the symptoms of, or prevents disease -- and there needs to be a disclaimer statement to that effect on the label. Be suspicious of overblown claims on the label or box, such as "totally natural," "completely safe," or "miracle cure." If you're unsure about a product, ask your doctor or pharmacist. Or call the supplement manufacturer and ask what studies they've done to support the claims they're making.