Consumer groups have been calling for better oversight of the many new caffeinated products on the market. Energy drinks, which are not required to display the amount of caffeine they contain, prompted more than 20,000 U.S. emergency room visits in 2011, double the number in 2007. And pure caffeine powder – which is virtually unregulated and powerful enough that a tablespoon is fatal for an adult – caused the accidental overdose deaths of two young men in 2014.Researchers constantly are learning more about how caffeine affects us. In many cases, it has significant benefits. Modest doses of caffeine improve vigilance and cognitive performance and decrease fatigue. Caffeine boosts athletic performance significantly and alleviates headaches. A 2015 studyshowed it is even associated with lower incidence of erectile dysfunction.