What is creatine? How do I take creatine? What are the side effects of creatine? What is the best creatine? Unless you just arrived from another planet, you should know that when it comes to muscle building supplements, creatine is the king! To date, creatine has proven to be the most research-proven sport supplement on the market to day. Creatine has collected hundreds of clinical studies that show increased lean muscle mass, improved energy levels, increased muscle strength and size and improved exercise performance.