There is no fountain of magical water that can reverse the effects of aging. Explorers abandoned the search for such a thing years ago. But the quest for everlasting youth isn't completely a lost cause. After the explorers gave up, scientists took over.

The premise is simple. If we can understand how we age, maybe we can stop it from happening or even reverse it. What science has found so far is that living is a paradox -- eventually, it kills us. All of the biological processes that take place in our bodies also damage our bodies, and while we repair most of that damage, naturally we can't repair it all. Over the years it adds up. As a result, our cells begin to deteriorate and we age [source: Olshansky, Hayflick & Carnes].

It's a stretch to assume that we'll ever find a way to stop aging completely. However, we do live a lot longer now than we used to, and it only makes sense that -- as we continue to make advances in technology and health care -- life expectancy may continue to increase. And the quest for eternal youth will undoubtedly continue to thrive. There are already a huge number of supplements available on the market that claim to slow down the process of aging. There are so many, in fact, that it's hard to know which ones, if any, actually work. When the dust clears, exercise, diet and getting enough sleep may always be the most reliable factors in staying healthy and feeling younger [source: Olshansky, Hayflick & Carnes].

If you do want to give anti-aging supplements a try, you need to know what to look for and what to look out for. After all, supplements can be expensive, and there are a lot out there that won't do anything more than a multivitamin. Some might even cause side effects that far outweigh their benefits. The bottom line is that you should be cautious.

Read on to find out about the top anti-aging supplements on the market today.