Creatine is the number-one supplement for improving performance in the gym. Studies show that it can increase muscle mass, strength and exercise performance (1Trusted Source, 2Trusted Source). Additionally, it provides a number of other health benefits, such as protecting against neurological disease (3Trusted Source, 4Trusted Source, 5Trusted Source, 6Trusted Source). Some people believe that creatine is unsafe and has many side effects, but these are not supported by evidence (7, 8Trusted Source). In fact, it is one of the world’s most tested supplements and has an outstanding safety profile (1Trusted Source). This article explains everything you need to know about creatine. What is creatine? Creatine is a substance that is found naturally in muscle cells. It helps your muscles produce energy during heavy lifting or high-intensity exercise. Taking creatine as a supplement is very popular among athletes and bodybuilders in order to gain muscle, enhance strength and improve exercise