Chocolate is derived from the cacao tree, and is generally made into sweets in the Western world, although it may also be drunk or eaten in its bitter form or with spice added. It is one of the most popular flavors on earth for sweets, and ranges widely in both style and cost. High-end chocolates have seen an upswing in recent years, but traditional standbys still make up a large portion of candy sales throughout the United States and Europe. In addition to often having sugar added, however, many people have heard that there is caffeine present in chocolate, leading to concerns that it can keep people awake or make them agitated.
Although there are a number of stimulants in chocolate, the caffeine present is negligible, and so does not have much of an effect on energy or mood. The sugar present in chocolate is much more likely to create a surge in energy or to make people feel agitated, especially in sweeter chocolates. Sweet chocolates actually have lower cacao contents, and therefore have even less of the already small amount of caffeine found in the cacao bean. There are three other main compounds found in chocolate that can affect mood and energy: theobromine, tryptophan, and phenethylamine.
Although phenethylamine does have a psychoactive effect, significant amounts don’t tend to reach the brain after ingesting chocolate. In spite of this, a widespread theory connecting chocolate to love was pushed in the 1980s, and persists to some extent. In truth, however, the phenethylamine is metabolized by an enzyme in the human body, MAO-B, so it ultimately has very little effect. Tryptophan, best known for its presence in turkey, is also present in moderate amounts in chocolate, but it has a calming effect, rather than an energizing effect.
Theobromine, one of the distinguishing alkaloids in chocolate, and the one which gives it its characteristic bitter taste, is in the methylxanthine class of chemicals. This is the same class that caffeine belongs to, and theobromine has some similar properties. There is roughly 20mg of theobromine in a gram of cocoa, which is not a negligible amount. Theobromine, like caffeine, acts as a diuretic, a vasodilater, and a heart stimulant. It is in fact responsible for many of the effects that people associate with caffeine in chocolate, and is responsible for poisoning in dogs and cats, which is why it is suggested that the animals not ingest chocolate.
As for caffeine itself, there is very little actually found in chocolate. When compared to common vessels of caffeine, it becomes apparent that the quantity of caffeine found in chocolate likely has no major effect on most people. One ounce (30g) of milk chocolate, for example, contains 6mg of caffeine, as compared to 19mg of caffeine in one ounce (30g) of coffee. The amount of theobromine in a similar quantity of chocolate, on the other hand, is much, much higher. As theobromine has similar effects to caffeine, although not as intense, it is likely that most people who see a response to chocolate are reacting to the theobromine.