Creatine is produced naturally in the body from the amino acids methionine, arginine, and glycine.  Methionine is an essential amino acid, which means it needs to be ingested by dietary means. Arginineis conditionally essential and glycine is non essential. Large sources of methionine can be found in meat, fish and milk. Studies show that vegetarian diets display lower total muscle creatine content compared to diets which contain meat. This may result in non meat eaters having to supplement with creatine even more so than no vegetarians for the following reasons:

ATP (adenosine triphosphate) is the power energy molecule responsible for all muscle contractions in the body especially high intensity short duration movements. Exercises lasting between 0-30 seconds are controlled by the phosphagen system which only runs on phosphocreatine. After 30 seconds the glycolysissystem starts taking over. This involves the synthesis of ATP from glucose. Anything after 2 minutes and the oxidative system which runs on the breakdown of fats, carbohydrates and some protein takes over. Keep in mind as the intensity increases carbohydrates will become the main fuel source due to the fact that fats and protein can't burn fast enough to make enough ATP's.

Phosphocreatine donates one phosphate to the ADP (adenosine diphosphate) molecule turning it into ATP, which now can be used as energy in the system. Creatine is used to rephosphorylate (adds phosphates back) the phosphocreatine molecule so that it can keep adding phosphates to the ADP making it ATP. Hence it is believed the more creatine you have in the creatine pool the longer you will be able to exercise. It is also reported an increase in power and strength will follow with more available ATP molecules in the system.  

Here are the suggested loading and maintenance phases of creatine

Loading Phase: 0.14g per pound of bodyweight daily.

Maintenance Phase: 0.0136g per pound of bodyweight

3-5 grams daily is recommended to insure skeletal muscle saturation of creatine (Sports Supplements Encyclopedia, Dr. Antonio)     

Restore after working out...

Our body releases the hormone insulin in the presence of carbohydrates. Insulin will do one of two things: 1) shove the digested carbohydrate molecule into the muscle cell for latter use as energy. 2) It can cram the carb molecule into a fat cell. Option 1 is usually followed after a hard workout. Your muscles are highly sensitive towards glycogen 30 -45 minutes after exercise. You can take advantage of this by mixing protein along with fast absorbing carbs and creatine. This makes for the ultimate muscle building cocktail. The protein will piggy back off the carbs along with the creatine and be shuttled into the muscle cells. The amino acids will rebuild damaged muscle tissue, the carbs will restore glycogen and the creatine will regenerate the creatinepool for ATP's later on.

Don't waste your money on those expensive creatine potions that claim an increased uptake of creatine. All they really do is add dextrose (sugar) to the creatine. You can do that yourself and save a ton of money.  

Mix in one scoop of whey protein with 8 -12 ounces of juice and 2-4 grams of any kind of creatine (I buy the cheapest whey and creatine I can get my hands on) and presto!

Does Creatine work?

It depends on what your definition of work is?  There is an initial weight gain of 5-10 pounds during the loading phase. This is due to the muscle cells being engorged with water. Hence the muscles look fuller and bigger. After about 4-6 weeks studies do indicate an increase in maximal strength, body mass, and fat free mass greater than strength training alone (Becque et al. 2000). So yes, it does work, but you have to ask yourself the question.... is it worth the money? By all means we're not talking HGHor anabolic steroids here. Nothing compares to the illegalstuff which is dangerous and as already mentioned illegal. If you think gaining 5-10 pounds and increasing strength about 5-10% is a big enough gain to spend the mullah, than by all means try it.

What about Side Effects?

Creatine is the most widely touted sports supplement to ever grace the store shelves. There have been numerous short term studies done on creatine with non negative outcomes to report.  Although it's critical to point out most studies have been short term, lasting only a number of weeks. Long term studies need to be addressed. Until then, cycle creatine using the alternative month method (one month on one month off) just to be on the safe side.   

   References    

Antonio PhD & Stout Ph. D, Sports Supplement Encyclopedia  

Becque MD, Lockmann JD & Melrose DR.  Effects of oral creatine supplementation on muscular strength and body composition. Medicine & Science in Sports & Exercise 32:654-658, 2000