Re: What is the drug/food additive Mark McGwire is taking? Is it dangerous?

Yes, the stuff that Mark McGwire takes is creatine.  It has caused a 
massive fad among people who think that if they take it, too, they will
turn into champion home-run hitters overnight.

There is an overwhelming notion that something that occurs naturally in 
the body is somehow good for you, and if you take LOTS of it, it's better.
Creatine occurs naturally in the body.  So does fecal matter, but you don't
see people rushing out to take that in megadose tablet form.

There are all sorts of products out there for which broad claims of health
benefits are made.  The majority of them have no supporting evidence
whatsoever.  There is "some" evidence (though no one can ever name the
laboratory at which the research was done, or the peer-reviewed journal in
which the findings were published) to indicate that creatine is good for
you, but even the people who push it admit that the long-term effects of
taking high doses of creatine are not known.  Poor Mr. McGwire may well
come down with terminal liver disease in ten years.  Or he may ascend to
Nirvana.  No one knows.

Personally, I think that creatine is yet another snake oil being sold by
greedy charlatans who will tell you anything to get you to buy their
product, and who don't give a rat's rump about your health.  The best thing
to do would be to talk to your personal physician and get his or her
opinion.