Theobromine is a caffeine-related stimulant that naturally occurs in cacao beans and is therefore in cocoa powders and chocolates. ConsumerLab's tests of dark chocolates and cocoas show them to contain about as much theobromine as heart-healthy flavanols. Dark chocolate can be particularly rich in theobromine, with a standard 40-gram serving often providing 300 to 400 mg of theobromine.
Although theobromine lowers LDL "bad" cholesterol, a recent study suggests that an amount of theobromine not much more than in a serving of dark chocolate may be a problem for people who need to control their blood sugar (such as those with diabetes or pre-diabetes). Also, be aware that theobromine can cause side-effects such nausea and headache in some people, and may interact with certain medications. Details are found in the Concerns and Cautions section of the Review of Cocoa and Dark Chocolates, which includes the amounts of theobromine discovered by CL in popular products, as well as their amounts of flavanols, caffeine and contaminants (lead and cadmium).
Also see answers to these questions:
Which dark chocolate bar has the most flavanols with the least calories? >>
How much caffeine is really in dark chocolate bars? >>
How much fat is there in chocolate? Is it saturated fat? >>
Why is there so much cadmium, a toxin, in cocoa powders but not in dark chocolate? >>
How much cocoa or chocolate do I need to consume in order to get a benefit? >>
Why does dark chocolate have iron in it? Is it, or cocoa, a good dietary source of iron? >>