Unless, of course, you're selling a supplement.
|No, not made from vampires and werewolves. Be sure to look for the utility belt, though.|
Of course, classified as a supplement, the "natural" (this term itself is meaningless) stuff can also be marketed with claims of various health effects, without need for basic science backing it up. It's a product that can exist in a number of loopholes both in marketing and availability.