11 things you should know about caffeine

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    Caffeine is the most commonly used stimulant in the world. It's cheap and easily accessible -- available in both natural sources, like coffee, tea and cocoa, and as an additive in sodas, energy drinks, over-the-counter drugs, a number of foods and some surprising other products.

    Researchers at Johns Hopkins University estimate that 80 to 90 percent of people in North America are habitual consumers of caffeine.

    While numerous studies suggest there are health benefits from caffeine (or caffeinated coffee), there can also be risks, especially when consuming too much. Read on to find out more about the substance that helps keep so many of us buzzing through the day...