Caffeine is beneficial. Whoever said that "one of the main ingredients in cocaine" is a total ******, that's like saying carbohydrates are one of the biggest ingredients in alcohol! STAY AWAY!
Caffeine increases body metabolism along with heightened mental capacity. If you drink a cup of coffee you are alert, have more energy and is proven (documentary on CBC as pertaining to athletes on different types of drugs) to increase muscle performance.
An athlete who ran the 100m after taking caffeine noticed a 4.9%+ improvement versus atheletes on the placebo.