Biology 202
2001 Second Web Report
On Serendip

Chocolate and cocoa have very complex chemical properties and many components. Among the most researched components of chocolate which are thought to have an effect on craving and addiction are fat, theobromine, caffeine, and salsolinol. (2).

Fat and sugar are substances naturally craved by the body, and thus although they may play a role in the allure of chocolate, they cannot be responsible for its appeal over other sweets. The caffeine in chocolate is sometimes implicated as part of its addictive properties. However, the amount of caffeine contained in one ounce of chocolate is about 5-35 milligrams, compared to the 140 milligrams found in a cup of brewed coffee. This does not discount the idea that caffeine plays a role in the appeal of chocolate, more likely it compounds the effect of other components. (3).

Theobromine, similar to caffeine but present in larger amounts in chocolate, is less potent than caffeine yet still may retain stimulatory effects in large amounts of chocolate. Concentrations of theobromine vary in different chocolate products, and its effect on humans through chocolate has not been consistently determined. (4).

An interesting compound studied last year by Melzig, et al, is salsolinol. It is a tetrahydroisoquinoline, (TIQ), or alkaloid of dopamine found endogenous in mammalian brains, and also found in cocoa and chocolate. This research has claimed that "salsolinol seems to be one of the main psychoactive compounds present in cocoa and chocolate and might be included in chocolate addiction." Similar compounds have the effect of inhibition of monoamine oxidase (a substance that reduces the amounts of norepinepherine acting on neurons), mirroring the effect of MAO inhibitors which are commonly used as antidepressants. Other effects reflect this general "antidepressant" influence on the brain. Interestingly, salsolinol was also found to bind with a relatively high affinity to D3 receptors, a subtype of dopamine receptor which is implicated in reward. This may be a factor in the rewarding properties which some people find chocolate to possess. Overall, this study suggested that chocolate may have the ability to psychopharmacologically induce craving and even addiction, especially in persons who are inclined to become addicted to other things. (5).

Some research has found that chocolate has the capability to stimulate the production of the body's endogenous opioids, or endorphins. Endorphins work on opioid receptors in the body, the same receptors on which morphine, heroin and other analgesics work, to cause relief from pain, create feelings of well being and even euphoria. Although scientists claim that one must eat many pounds of chocolate to create any noticeable effect, some chocolate addicts may disagree.

Some evidence for an effect of chocolate on endorphins comes from a study done on 41 women, half normal eaters and half diagnosed with bulemia nervosa, a disorder marked by binge eating. (Binge eating is used here to be an example of extreme craving for a food; usually in bulemics the food craved is chocolate or other items with high fat and suger content.) After injection of the drug naloxone to the experimental group, binge eaters ate considerably fewer calories and often favored low fat foods over chocolate. It also decreased the "hedonic effect" of the preferred foods in both the normal eating and binge eating groups. Naloxone is an opiate antagonist, which binds to and blocks opiate receptors in the body. It is used in many studies to determine the effects of opiates, and to detect the presence of endorphins, as in this study. The results of this study suggest that during binge eating, or eating of foods which one craves very strongly, endorphins are released and naloxones' blocking of endorphin binding is manifested in the lack of further craving. Also, the pleasure from foods such as chocolate is decreased, leading to preferences shifting from foods with a high sugar and fat content to low fat foods. (6).

Research similar to the previously described study but performed with rats provided the basis for the idea that sweet and fatty foods induce the production of endorphins. Rats, who naturally will eat sweet foods over their normal feed, will choose the normal food over sweet after an injection of naloxone (6).

Tuomisto, et al, performed an experiment in 1999 on 31 subjects to determine whether there exist certain physiological and psychological characteristics in addiction to chocolate. Heart rate and salivation were the measured physiological responses to chocolate cues, and self-reporting was used to measure psychological responses. It was found that self-proclaimed chocolate "addicts" had more salivation than controls in the presence of chocolate cues, and also reported more negative affect, craving, anxiety, and even depression. Addicts also scored significantly higher on the Disinhibition scale of the TFEQ, Three-Factor Eating Questionnaire, meaning that their control of eating is affected by external factors more easily. This correlates with the eating style of bulemics and the severity of binge eating. (7).

With so many possible interacting factors playing into people's chocolate cravings and "addictions," it is difficult to say with any certainty that these effects are truly physiological. All scientific findings aside, we must admit that psychology may have more than a little to do with our love of chocolate. Children are not the only ones who want the most that which they can't have. Classified in our society as an "indulgence," to most people, chocolate is a small sinful treat. Many associate it as a reward, and this may contribute to our perception of chocolates' reward properties. Physiologically, we have much to learn about the effects of cocoa and chocolate and all of their constituent parts. Psychologically, we are not lacking the "chocoholics" for the other end of this research...

WWW Sources

2)Chocolate.

3) Does cocoa have caffeine in it?, International Cocoa Organization.

4) Theobromine: Chocolate's Caffeine Cousin .

5) In vitro pharmacological activity of the tetrahydroisoquinoline salsolinol present in products from Theobroma cacao like cocoa and chocolate..

6) Naloxone, an opiate blocker, reduces the consumption of sweet high-fat foods in obese and lean female binge eaters .

7) Psychological and Physiological Characteristics of Sweet Food "Addiction".

| Course Home Page | Forum | Brain and Behavior | Serendip Home |