Theobromine

Because cocoa carries both methylxanthines, a cocoa drink or extract can deliver some caffeine along with its theobromine [1]. In COSMOS, a large trial supported by an investigator-initiated grant from Mars Edge, which supplied the cocoa extract, the extract contained modest amounts of theobromine (about 50 mg a day) and caffeine (about 15 mg a day) [2]. The same paper noted that food-based cocoa interventions are highly susceptible to variation in flavanol, theobromine and other bioactive content [2].

Human research on theobromine is thin. A 2011 review described its effects in people as underresearched, possibly because it was assumed to be behaviorally inert [3]. A 2019 review reported that in animal studies a single dose of theobromine had a smaller and delayed effect on cognition compared with caffeine, and concluded that its action on cognition, alone or with caffeine, is underexplored [1].

Research on cocoa has placed a particular focus on its flavanols, but cocoa also contains theobromine and caffeine [1]. The 2011 review argued that research ought to include caffeine as a comparative agent [3], and it judged caffeine the most convincing of the cocoa constituents proposed to explain people's liking for chocolate, though a role for theobromine could not be ruled out [3]. So when a cocoa study reports a change in alertness or mood, look at whether the control product matched the methylxanthine content.

The same review noted that animal toxicology findings for theobromine cannot be extrapolated to humans, and that domestic animals need to be kept away from chocolate and cocoa-containing foods [3].

For the graded evidence on cocoa, see Cocoa flavanols; for the better-studied methylxanthine, see Caffeine.

• Flavanols
• Adenosine
• Stimulant