Contrary to popular belief, creatine is not a steroid— so don’t worry about going all Hulkamania after reading this. Creatine is a natural compound produced by the kidneys, pancreas, and liver that plays an important role in releasing energy when the body moves quickly or powerfully. Used as a supplement, creatine supposedly boosts muscular performance. But is it really safe?
Energy Boost? — The Need-to-Know
So here's the breakdown: Creatine created by the body is stored mostly in muscle cells. During short-term bursts of speed or strength (like sprinting or jumping) it helps release energy by regenerating ATP, or the body's go-to pathway for immediate energy. By providing more immediate ATP for energy, creatine can improve muscular strength and power, and can even increase muscle size by pulling water into the muscles, giving them a fuller look  . But don't worry— research suggests creatine doesn't "steal" the body's water or cause dehydration as is sometimes thought  . In fact, one study found that it doesn't even seem to hinder hydration in endurance athletes when exercising in the heat  .
Since the kidneys filter creatinine, the byproduct of creatine, there’s speculation that supplementation can lead to renal dysfunction  . But when used by healthy individuals and taken as directed  , studies suggest creatine is a relatively safe supplement, with most side effects being minimal gastrointestinal problems like gas and bloating    .
Without supplementation, the body creates and uses roughly two grams of creatine per day of its roughly stored in the body. In addition, muscles can store around 20 percent more. And after hitting the body's maximum storage point (about 120 grams throughout all muscles), consuming more creatine doesn’t further affect concentration levels— a point referred to as saturation or maximum concentration.
Now, there are two methods used to get to this point. The first (and the strategy used in most studies) is undergoing a "loading" phase consisting of twenty grams (broken into four five-gram servings per day) every day for four to six days. After this phase, anywhere from two to five grams are taken daily to maintain peak levels. The second method (which may be more suitable for those who aren't sure about how they will tolerate creatine) simply consists of taking three to five grams daily, in which hitting saturation will take about one month and the doses can be maintained to sustain peak levels.
In terms of creatine's ability to boost performance, studies (and uses!) vary widely. One study looking at the supplement's effect on jumping performance suggests an an improvement of up to 2.8 percent (likely beneficial) , while studies looking at the effect creatine had on body mass and performance found "small but significant increases in lean body mass and upper-body exercise" .
Considering Creatine — Your Action Plan
These days, creatine comes in many shapes and sizes. While options include creatine phosphate, citrate, malate, and ester, creatine monohydrate is the most well known and widely used among sports professionals. And since it’s used in most research studies, monohydrate’s safety is also better documented that its cousins .
As for the most effective way to take it, research suggests (as does Greatist Expert Robynn Europe) that taking creatine with carbohydrates increases uptake into muscles, making them an essential part of the dose . That's why many popular creatine supplements come with a heavy dose of carbohydrates in the mix. But without protein added to the mix, too, it can take nearly 20 grams of carbohydrates per one gram of creatine (!) for proper absorption. The addition of protein, however, makes the process of regenerating ATP easier, allowing the user to cut carbs by as much as half .
Although creatine supplementation started with the intent of increasing sports performance, its list of effective uses is growing. The supplement is now used in clinical settings to help those with Parkinson’s disease, heart failure, and also to increase strength and brain function for those with some muscular and neurological disorders    .
For supplement skeptics out there, creatine can also be found in whole foods such as red meats and fish. But don’t think eating these foods everyday will pump up those muscles as much—it would take downing dinosaur-sized portions (we’re talking one pound of red meat per 2 grams of creatine) to yield the same results.
If considering creatine, remember that there are always special considerations when dealing with unregulated supplements. It’s always best to ask a health care professional before use. Those with preexisting kidney problems, or any complications that intermingle with kidney function such as diabetes, should be especially careful  .
Robynn Europe, Trainer and Bodybuilding Coach: ACE, USSA, NPC: "Carbohydrates are what makes [creatine monohydrate] (CM) available for use because insulin is an agent for bringing the creatine into skeletal muscle cells. When people experience bloating, it's usually because creatine and water are sitting outside the cells instead of inside. If they'd had enough easily digestible carbs with the creatine, bloating would never be an issue. The main reason other forms of creatine have become popular is because people are so scared of carbs, and the other forms claim to be "absorbed" more easily (read: without carbohydrates or bloating). Unfortunately, there's very little research supporting the efficacy or increased absorption of these other forms.
Most popular (read: effective) creatine supplements come with a heavy dose of carbohydrates in the mix (cornstarch or glucose, usually), and the cheaper versions which are straight CM should be taken with juice [for carbs] (grape, I find, works the best because of the sheer amount of simple sugar in an 8oz glass."
Jason Edmonds, Researcher/Athlete: BS Biology, Olympic Weightlifter: "It's also interesting to note that there's evidence suggesting that creatine supplementation can alter serum dihydrotestosterone (DHT) levels in men. DHT is a biologically active metabolite of testosterone that acts as a powerful androgen. One study found that three weeks of creatine supplementation (7 days of loading, followed by 14 days maintenance) resulted in a 56% increase in serum DHT levels after the 7 day loading phase (25 grams of creatine per day), and remained elevated 40% above baseline after 14 days of creatine maintenance dosing at 5 grams per day. Testosterone levels were not affected. It's not clear what type of short or long term effects this increase in DHT might have (if any) ."