By Mark Lebetkin
The Active Times

Dietary supplements can be scary.

It’s not uncommon to walk into the supplement aisle in your local pharmacy -- or grocery store -- and feel like you've entered the Wild West of the health world. Officially considered food by the FDA, these pills, powders, tinctures and teas are not held to the same standards as drugs, and yet their makers make wild promises that are hard to ignore: they'll make you smarter, calmer, fitter, happier and healthier. They’re "natural" because they're made of plants like ginseng and gingko biloba, or things you eat, or compounds your body produces anyway.

And you're right to be suspicious. The FDA doesn't ensure standardization, meaning two capsules of St. John’s wort from two makers are likely to be far more different from each other in terms of potency and quality than two brands of ibuprofen. The FDA ensures those are virtually identical.

And then there's the question of what works.

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Some supplements can be very effective, but potentially very dangerous. Take ephedrine, for example. This extract from the ephedra plant has been found to be an effective weight-loss supplement when paired with caffeine (1,2,3) and is found in so-called diet pills (and is used to make crystal meth, by the way). It can still be bought over the counter in small quantities in Sudafed or other nasal decongestants, but can be addictive and cause serious heart problems -- even sudden heart attacks -- when not used under the guidance of a doctor. And it’s banned in most sports, for that matter.

So which ones do work and won’t get you kicked out of the NCAA, or worse?

Because supplements don’t have to go through the same approval process as drugs, the level of science around any given one is far below what you’d expect for something your doctor prescribes. That said, many supplements, like creatine, melatonin, and fish oil, have been through the scientific wringer, and although they’re not as well tested as their pharmaceutical counterparts, turn out to work almost as well -- and better in some cases.

We did some digging into the databases and came up with some supplements that do (some of) what they say they do. These won't work miracles, but they have been shown to work.

As with "normal" drugs, you should consult your doctor before taking any of these since they may not be for all ages and health conditions, and may interact with other medications.

Many of the promised effects of these supplements wither under scientific scrutiny. For example, evening primrose oil is sold as a way to reduce PMS symptoms, but human trials have found it to be only as useful as a placebo. Don’t waste your money.

More Stories from The Active Times:
-- 37 Superfoods to Start Eating Right Now
-- 50 Fittest Cities
-- 15 Crowd-Free National Parks
-- Simple Relaxation Techniques for Stress

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