Now, energy drinks are widely popular for the public. But energy drinks are marketed as beverages that boost mental and physical performance. Caffeine is the most common stimulant in these drinks, but some brands contain other plant-based stimulants, such as guarana and ginseng. Numerous studies have suggested energy drinks can have negative health implications. A 2013 study reported by Medical News Today, for example, found energy drinks alter the heart function of healthy adults, while another study linked energy drink consumption to other unhealthy behaviors, such as smoking.