Energy drinks are the fastest-growing part of the beverage industry, reports the New York Times, with sales in the United States reaching more than $10 billion in 2012 — more than Americans spent on iced tea, or sports beverages like Gatorade. The drinks are now under scrutiny by the Food and Drug Administration after reports of deaths and serious injuries that may be linked to their high caffeine content. However that review ends, one thing is clear, interviews with researchers and a review of scientific studies show: the energy-drink industry is based on a brew of ingredients that, apart from caffeine, have little, if any benefit for consumers.