Chocolate
Caffeine

One tablespoonful (5 grams) of dry unsweetened cocoa powder has 12.1 mg of caffeine and a 25-g single serving of dark chocolate has 22.4 mg of caffeine. Although a single 7 oz. (200 ml) serving of coffee may contain 80–175 mg, studies have shown psychoactive effects in caffeine doses as low as 9 mg, and a dose as low as 12.5 mg was shown to have effects on cognitive performance.
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