When a chicken crosses a road, it better have a good reason.  The risks are real, the outcome: death*.   Now that I have your attention...

Dietary supplements can present a similar (but less bone-chilling) situation.   What is a dietary supplement?  They range from safe and beneficial (multivitamins) to unsafe and unproven (ephedra, androstenedione).  They are basically unregulated by the US Food and Drug Administration.

Problems with dietary supplements include

• Since they are unregulated, their manufacturers do not have to prove they are effective for any purpose. 
• In fact, it is a very small percentage of them that have stood up to clinical trials and demonstrated consistent benefit.
• Since they are unregulated, there is little pressure for a manufacturer to put in the bottle what appears on the label. 
• Independent groups such as consumerlabs.com have repeatedly shown that at a high frequency, dietary supplements contain much less or more of an active ingredient than the label states, or they are contaminated with pesticides, heavy metals, or other herbs.
• Due to aggressive lobbying by the dietary supplement industry, even when it is plain as day that an agent is harmful, it can take the FDA years to ban it (as occurred in the case of ephedra)
• In the setting of little oversight, there is little self-restraint on the part of the industry.  Take for instance beta carotene and vitamin E.  Despite much speculation that these antioxidants would help everything from heard disease to cancer, to painful menses, a number of large studies have pretty much shown that both of these agents actually increase risk of death.  Yet these continue to be sold every day.

So the point here is a supplement should be well proven to be both safe AND effective before it merits crossing the road to take it, because the risk is real.

Are all dietary supplements unsafe?  No!  I will save my short list of safe & effective ones for later.  Here is a preview:

• Several recent studies have shown vitamin D supplementation at about 1000 IU per day (double the USRDA recommendation) significantly reduces cancer.
• Calcium at about 1000 mg per day helps keep bones strong.
• A variety of foods (wine, dark chocolate, tea, almonds to name a few) have good evidence of lowering risk of heart disease

So be a chicken: think twice before crossing the road to take a dietary supplement.

*Fortunately it's rarely an issue, since chickens spend their entire lives in a 1 foot cube cage.  So rest easy, people.