LabDoor also focuses on healthy choices, seeking to chemically test common supplements such as vitamins and energy drinks, to determine their actual content.

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U.S. regulators have capped caffeine at roughly 6 milligrams an ounce for traditional sodas such as cola under a decades-old rule, but haven't done the same for energy drinks, many of which are marketed as dietary supplements and subjected to less government oversight.

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In March, Monster Energy Corp. decided to begin marketing its products as beverages instead of dietary supplements and said it would include the caffeine content on each can of its energy drinks.

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