Creatine
is an amino acid (protein building unit) that's found naturally in meat and
fish, and also manufactured by the human body in the liver, kidneys, and
pancreas. It is converted into two different molecules, creatine phosphate or
phosphocreatine, the form under which it gets stored in the muscles, to be
utilized as energy source when the need arises. During high-intensity,
short-duration exercise, such as lifting weights or sprinting, phosphocreatine
is converted into ATP (adenosine tri-phosphate), the major molecule that
transfers energy among cells and organs.

The
creatine that is normally present in human muscle is obtained from two
potential sources: dietary (animal flesh), and/or internally manufactured. The
amount that isn't present in the diet is easily made by the liver and kidneys
from a few amino acids (glycine, arginine, and methionine). A 70kg adult has
about 120g of creatine in the muscles, and the daily turnover is roughly 2g.
About half of this amount is replaced by the diet and half synthesized
endogenously (within the organism).

The
exogenous (from diet and/or supplements) intake of creatine appears to
negatively affect the endogenous production of creatine, so, the more creatine
is present in the diet, the less creatinine is produced endogenously. Creatine
is eliminated from the body by the kidneys either as creatine, or as
creatinine, a product of the metabolism of creatine.

In
one of the studies which looked at intermittent, high intensity workout, it was
discovered that caffeine completely abolished the ergogenic effect (i.e., which
enhances physical performance) of creatine supplementation. Paradoxically, a
good number of the commercially available creatine supplements contain both
creatine and caffeine. Another important fact is that Creatine does not
seem to improve performance in exercises that requires endurance, like running,
or in exercise that isn't repeated, although study results are mixed.

Short
term (< 2 weeks) exercise studies have not reported any adverse events
associated with creatine supplementation. Long term studies that evaluate the
safety profile of long term use of creatine have not yet been run. Sporadic
reports of increased muscle cramping (especially during exercise in the heat),
nausea and other gastrointestinal disturbances, elevated liver transaminases,
and acute renal injury, exist.

Dosing:

o    Loading
dose with 20 grams per day (or 0.3 grams per kg) for 5 days followed by a
maintenance dose of 2 or more grams (0.03 grams per kg) daily.

OR

o    Loading
dose of 9 grams per day for 6 days.

o    Some
sources suggest that, instead of acutely loading, similar results can be
obtained with 3 grams per day for 28 days.

During creatine supplementation, the water intake
should be increased (to avoid kidney damage) to no less than 2 liters per day.

It is worthy of
noting that creatine supplementation, in the dosages commonly used, results in
urinary concentrations that are 90 times greater than normal. This creates
potential kidney injury (nephrotoxic). Recently, a baseball player for the
Houston Astros was determined to have suffered from dehydration, kidney stones,
and transient kidney damage as the result of creatine supplementation.
Additionally, the deaths of 3 collegiate wrestlers this past year are being
investigated to determine what role creatine supplementation may have played.

Moreover,
one needs to always keep in mind that impurities are present in virtually all
manufactured products, and this by itself is a source of health hazard. An
example  is the outbreak of eosinophilia-myalgia syndrome, which took
place back in the late 1980's, whereby over 30 deaths were attributed to a
contaminant present in L-tryptophan, an amino acid supplement widely taken as a
sleep aid.