Americans are consuming more energy drinks, with a notable increase among young adults, survey data show. Energy drinks are non-alcoholic beverages with high levels of caffeine or other stimulants, plus amino acids, herbs and vitamins. They’re marketed as fatigue killers and refreshing beverages that can improve physical and mental performance – but this may come at a price, researchers say. They point to high caffeine levels in energy drinks and a “rapidly expanding body of literature” that suggests negative health effects and risky behaviors may be linked to high consumption of the beverages. Beyond the caffeine, “people who drink energy drinks consume approximately 200 calories from these beverages daily, which is considerably higher than other sugary beverages like soda,” Sara Bleich at Harvard T. H. Chan School of Public Health in Boston told Reuters Health. Furthermore, ingredients in some of the drinks – such as guarana and taurine – are so poorly studied it’s hard to say whether they’re safe in large quantities. As reported in the American Journal of Preventive Medicine, Bleich and her colleagues analyzed data collected from 9,911 adolescents, 12,103 young adults and 11,245 middle-aged adults between 2003 and 2016 during biennial government health surveys. As part of the surveys, participants were asked to recall what beverages they had consumed in the previous 24 hours. Among young adults (i.e., ages 20 to 39), 5.5% reported consuming energy drinks in 2016, up from 0.5% in 2003. The increase was less pronounced for adolescents, whose energy drink consumption rose from 0.2% in the earlier survey to 1.4% in the later one, and for middle aged Americans, whose consumption rose from 0% to 1.2%. On average, energy drink consumers had higher caffeine intake compared with those who did not consume the drinks: 227 mg vs 52.1 mg among adolescents, 278.7 mg vs 135.3 mg among young adults, and 348.8 mg vs 219.0 mg among middle-aged adults. Males consumed more energy drinks than females, the researchers found. And young adults with at least some college education consumed less of these drinks than their peers who had no education beyond high school. For adults, caffeine in doses up to 400 mg (about five cups of coffee) is generally recognized as safe by the U.S. Food and Drug Administration, although some people are sensitive to lower doses. Higher amounts can cause health effects like high blood pressure, insomnia, irregular heartbeats and other problems. In a 2017 study, drinking 32 ounces of energy drink was associated with potentially harmful changes in blood pressure and heart function beyond those attributable just to caffeine. (https://reut.rs/2YNXBLx) The authors of that study concluded that the changes might not be worrisome for healthy individuals, but people with heart conditions might need to be cautious about consuming energy drinks. Data from the current study suggest that consumption of energy drinks might have been leveling off or even declining in the last few years of the study, the researchers say, but they couldn’t confirm a trend. “The reason for this apparent leveling off is unclear. It could be that, like sugary beverages generally, consumption of energy drinks is becoming less popular among adults and adolescents,” Bleich said. Still, she and her colleagues conclude, “Requiring caffeine labeling on energy drinks and establishing an evidence-based upper caffeine limit for these beverages may be important to reduce the potential negative health impact on consumers.”