Chocolate: Sweet News

By Ellen Kuwana
Neuroscience for Kids Staff Writer
December 22, 2000

The Complexities of Chocolate

During the holidays, people eat lots of sweets. Chocolate is one sweet that is popular any time of the year. Chocolate is not only a delicious treat, it is a very complex food: it contains at least 380 chemicals that contribute to its taste.

News to Chew On

Tomas Herraiz, a Spanish chemist, has isolated one more chemical from chocolate. Dr. Herraiz has found alkaloids called tetrahydro-beta-carbolines in chocolate and cocoa. The newly discovered compound, tetrahydro-beta-carboline, and the family of chemicals it belongs to, beta-carboline alkaloids, affect the central nervous system in several ways:

  • They are mild inhibitors of an enzyme called monoamine oxidase (MAO). MAO is an enzyme that destroys monoamine neurotransmitters (norepinephrine, dopamine, serotonin).

  • They work by inhibiting the reuptake of the serotonin. The net result is an increase in the amount of serotonin within the synapse.

  • They inhibit the binding of benzodiazepines on their receptors. This results in a decrease in the level of the neurotransmitter GABA.

Serotonin and dopamine have been shown to influence mood, food intake and compulsive behaviors. Because alkaloids affect these neurotransmitters they may also affect these behaviors. Many people say that chocolate makes them feel happy and relaxed. Perhaps you have felt these feelings after eating chocolate. Some people even "crave" chocolate, hence the sort-of-serious name "chocoholic," for someone who is "addicted" to chocolate. In fact, the alkaloids tetrahydro-beta-carbolines have been implicated in one addictive behavior: alcoholism.

Do Alkaloids Cause Chocolate Craving?

Well, it's not that simple. Chocolate does not contain a large amount of alkaloids and darker chocolate has higher quantities of alkaloids than lighter chocolate. However, alkaloids are found in foods that are not addictive. Also, there are many chemicals in chocolate, and tetrahydro-beta-carboline is just one of them -- a newly discovered one. So, another piece of the puzzle has been found, one that scientists hope will add to the big picture of why chocolate is so appealing.


  1. Chocolate and the Nervous System from Neuroscience for Kids

  2. "Understanding Chocolate Cravings," written by the American Chemical Society, published in Science and Children, Jan. 2001, p.12.

  3. Herraiz, Tomas, "Tetrahydro-beta-carbolines, Potential Neuroactive Alkaloids, in Chocolate and Cocoa," J. Agric. Food Chem., 2000, Vol. 48, No.10, pp. 4900-4904. Published on the WWW: 9/15/2000.

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