The term “nootropics” refers to a category of supplements, which have been shown to boost cognitive ability and memory. They’re often combined with caffeine, green tea extract and other common stimulants. These ingredients can help you concentrate, enhance your memory and focus, and even increase your overall energy levels. These supplements are gaining popularity among Silicon Valley types and biohackers alike. Here are 6 of the best nootropics vitamins for improving your brain power.