So, there's this multi-billion dollar industry that uses tricks, the guise of scientific objectivity, marketing ploys, your own insecurity, and concern for your health to get you to purchase a products that do nothing for you.  It is called the dietary supplement industry.  For the most part, their products do not elevate the average human above that which the average human was already capable.  And in the cases when they do, they are most likely to be spiked with an actual drug.  Drugs actually do change what the average human is capable of on there own, just take a look at the current Mr. Olympia, Jay Cutler, he did not get there with exercise and diet alone.

Drugs, in certain sense, are great.  They work, you are not wasting your money buying a drug.  However, if you buy a supplement that is spiked with a drug to make it effective, you are at risk of a host of drug-related problems.  Supplements are not regulated by the FDA.  That is so important I will repeat it, supplements are not regulated by the FDA.  The FDA only takes action on a supplement company if the supplement turns out to be dangerous or contain a regulated substance (drug).  So, when you take a spiked supplement you could be taking an unregulated dose of an unknown drug.  Check out these to articles on the supplment industry to get an idea of the kind of thing that goes on:

This New York Times article goes into drug spiking and supplements.

This Men's Health article goes into how supplements vendors sell you crap you don't need.

Enjoy, and remember, if it seems to good to be true, it probably (most certainly, definately, surely) is...