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Biology 202
2001 Second Web Report
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Chocolate is made from the seeds of the tropical tree, Theobroma cacao. Theobroma is the Greek term for 'food of the gods.' In Aztec society chocolate was a food of the gods, reserved for priests, warriors and nobility. The Aztecs used cacao beans to make a hot, frothy and bitter beverage called chocolatl. Chocolatl was a sacred concoction that was associated with fertility and wisdom. It was also thought to have stimulating and restorative properties. The bitter drink was first introduced to Europe in 1528. However, it was not until 1876 that milk, cocoa powder and cocoa butter were combined to form what we now know as chocolate (1).
Today, production and consumption of chocolate is a global affair. People crave chocolate more than any other food. In the United States, the typical person eats 11.5 pounds of chocolate annually (2). What makes chocolate the food that is craved more often than any other food? Yes, chocolate tastes good, has a beautiful texture and melts in your mouth, but there must be more to chocolate than what meets the lips. In fact, chocolate is made up of chemicals associated with mood, emotion and addiction. Many people eat chocolate as a comfort food when they are depressed or stressed. The question is, do people crave chocolate because their bodies and brains are addicted to the chemicals in it or do people crave chocolate because they have a psychological attachment to it?
Substances found in chocolate, such as phenylethylamine, theobromine, anandamide and tryptophan trigger mood enhancing chemicals and neurotransmitters to be released in the brain. Phenylethylamine is a chemical found in the body that is similar to amphetamine. It helps mediate feelings of giddiness, attraction, euphoria and excitement. Researchers believe phenylethylamine causes the brain to release mesolimbic dopamine in the pleasure centers of the brain, which peaks during an orgasm. This may be why women report to prefer chocolate to sex. However, tests have shown that most of the phenylethylamine in chocolate is broken down before it reaches the brain. So, the amount of phenylethylamine that actually reaches the brain is unknown (1), (3).
Theobromine is a close structural relative of caffeine, but has one-tenth the stimulating effect caffeine has. Although theobromine is a weak stimulant, it can increase pulse rate. And, withdrawal from theobromine has been found to cause migraines. The level of theobromine in commercial chocolate varies from bar to bar. Milk chocolate bars contain the lowest levels of theobromine. Thus, it is unlikely that theobromine alone is responsible for chocolate cravings (3), (4).
In the mid-nineties a study done by Doniele Piomelli and his coworkers found that chocolate contains substances that mimic the effects of marijuana. Piomelli found that anandamide, produced naturally in the brain and also found in chocolate, activates the same cellular receptors as THC, the agent in marijuana that causes a person to feel "high". When a person smokes marijuana THC goes into the brain and activates all cannabinoid receptors. Enzymes break down anandamide shortly after it is produced by the brain, thus limiting the duration of the pleasurable "high". Chocolate does not contain enough anandamide to produce a global high like marijuana (2). Plus, other researchers have found that most of the anandamide found in chocolate is broken down by stomach acid before it even reaches the blood stream (5).
In addition to finding anandamide, Piomelli also discovered two anandamidelike compounds, N-oleoythanolamine and N-linoleoylethanolamine, in chocolate, which delay the breakdown of anandamide in the brain. He speculates that the anandamidelike compounds prolong the pleasurable sensations associated with the body's own natural production of anandamide rather than the anandamide found in chocolate. The anandamidelike compounds do not bind to cannabinoid receptors, so the pleasurable effect of chocolate is entirely dependent on how much anandamide in naturally produced in the brain at the time chocolate is consumed. If anandamide is not present in the brain the anandamidelike compounds may not have any effect at all. And, if anandamide were present, the effect of the anandamidelike compounds would be limited to the areas of the brain where anandamide was naturally produced. This explains why chocolate does not produce a marijuana-like global "high", but might explain a physiological chocolate craving when anandamide is present in the brain (2).
In addition to marijuana like substances, chocolate also contains tryptophan, an essential amino acid, which plays a role in the production of the neurotransmitter serotonin. Serotonin is a calming neurotransmitter that makes people feel relaxed and satisfied and is essential for a well-balanced mood. Many people eat chocolate to relieve anxiety, but is unlikely that tryptophan is solely responsible for chocolate cravings or a chocolate addiction because it can be obtained from other food sources, such as carbohydrates, as well (1).
Chocolate contains bioactive agents that increase the level of serotonin in the brain, prolong the effects of anandamide in the brain, produce mild stimulation, and signal the release of mesolimbic dopamine. However, few studies have invested the role of chocolate's bioactive agents as the basis of chocolate cravings. In a 1994 study men and women were given milk chocolate, white chocolate, which lacks cocoa and the bioactive agents found in chocolate, cocoa capsules, which lack the sensory components of chocolate, or placebo capsules. The researchers found that only milk chocolate fully satisfied the chocolate cravings of the subjects. In addition, both men and women preferred white chocolate to the cocoa capsules. This suggests that chocolate craving can be attributed to its aroma, texture, sweetness and psychological associations with chocolate (6).
Psychological associations with chocolate are influenced by a multitude of things, including hormonal and cultural influences. Women's bodies scream for chocolate when premenstrual food cravings surface once a month. Many researchers argue that women crave chocolate prior to menstruation because it contains high levels of magnesium. Women experience magnesium deficiency prior to menstruation. However, many other non-craved foods also contain high levels of magnesium (1).
Debra Zellner, Ph.D., a psychologist and professor at Shippensburg University, believes women crave chocolate because they have turned it into a nutritional taboo. It tastes wonderful, but it's sinful because it's loaded with fat and calories. Women crave chocolate when they are feeling low or before their periods because they have told themselves it is something they cannot have. Zellner conducted a study comparing chocolate cravings in Spanish and American women. She found that Spanish women, who did not see chocolate as a forbidden food, craved chocolate less than American women did. Zellner attributes chocolate cravings entirely to psychological associations and believes the bioactive chemicals found in chocolate occur in too small of amounts to have a neurological impact (7).
Research investing both the physiological and psychological basis of chocolate cravings is pretty inconclusive. It is most likely a combination of both. If chocolate cravings were entirely physiological people would not eat chocolate for psychological reasons. Most researchers believe chocolate's sensory qualities, chemicals, cultural values, social values and hormonal influences all play a role in chocolate cravings. It is the complete chocolate bar that people crave. Not one single chemical or quality can be solely responsible for satisfying a chocolate craving.
1)CHOCOLATE, on the Chocolate web site
2)Prescription-strength chocolate, on the Science News Online-Food for Thought web site
3)Chocolate and Anxiety, on the About the Human Internet web site
4)Theobromine: Chocolate's Caffeine Cousin, on the About the Human Internet web site
5)Chocolate "addiction" A Fiction?, on the Personal MC web site
6)Health and Happiness-does chocolate have it all wrapped up?, on the IFIS Hot Topic web site
7)Chocolate: A heart-healthy confection?, on the CNN web site
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