The Illuminated Brain

A weblog on neuroscience

The Neurobiology of Chocoholism

Written by Anders on 0 comments

Chocolate

“I gotta have it.” is the first thought in an addicts head. I need it, and I need it right now. Addiction puts itself beyond reasoning, logic, and sometimes not even our will-strength can conquer the urge.

The thought isn’t satisfied before it is fulfilled. You are probably thinking that this has nothing to do with chocolate, but some suggest that it does. Chocolate is for many people a strong drug. Some people say, depending on the type, that chocolate can act as a: relaxant, stimulant, empathogenic, aphrodisiac and euphoric drug.

Looking back at the history of chocolate, the origin of chocolate is said to be in Mexico [1] where Mayas, Incas and Aztecs cultivated the cacao tree (Theobroma cacoa). Theobroma cacoa translates to “a gift of the gods”. One could argue, that a large amount of people, find merit in that translation.

However, innocuous chocolate may be, scientists were interested in the special effects of this “gift from the gods” and found people who claimed they could not live without chocolate, demonstrating the power of the substance. The scientists described, from their various experiments, people addicted to chocolate, and terms such as chocoholic and chocoholism emerged.

“Chocolate is cheaper than therapy and you don’t need an appointment.” – Unknown

As the above quote suggests the effects of chocolate are strong. Let us take a closer look at how chocolate affects the brain.

Chocolate: Replacing Vicodin?

Opiates are named after the active ingredients in the plant opium. Exogenous (from outside the body) opiates are drugs such as morphine and codeine, and the semi-synthetic drugs such as heroin, hydrocodone (Ever seen House MD? Hydrocodone is the active constituent in House’s Vicodin pills) and oxycodone. These drugs are highly addictive, as they bind to opioid receptors in the brain, affecting pain, stress and pleasure.  Luckily, one can agonize these opioid receptors without touching base with narcotics.  Chocolate, is a way to do just that.

A review-article called Chocolate: Food or drug? by Taren et al, suggests that chocolate addiction may be mediated through endogenous (from inside the body) opiate signaling. An opiate antagonist naloxone was found to decrease taste-preference for high-fat and sweet foods, chocolate being the prime example. They did note, however, that chocolate addiction may be due to a variety of factors, and not solely mediated through endogenous opiate signaling.

Moreover, the article presented a hormonal hypothesis, as to why chocolate consumption is modulated by hormonal fluctuations, and thereby preferred by women. According to the article, an open-ended survey about food cravings administered to undergraduates, chocolate was the most mentioned craved substance. 32% of the women who craved chocolate said it correlated with their menstrual cycle.

The purported mechanism for the chocolate craving during the menstrual period is that estrogen levels are “moderate” and progesterone levels are “high”. The ratio between estrogen and progesterone is said to affects women’s food intake. The neurotransmitter mechanism involved in this pre-menstrual carbohydrate craving is hypothesized to be through a reduction of serotonin levels, leading to increased carbohydrate cravings. The serotonin mechanism makes sense, since a reduction in concentrations of serotonin, would mean that the brain would yearn for more serotonin, and since chocolate is an excellent source for tryptophan, the amino acid precursor for serotonin, chocolate is a natural choice.

Rediscovering Prozac

An article in 2007 by Mueller et al [2] proposed that eating a piece of chocolate affected negative mood-states, but not positive or neutral. The study suggested that it was highly unlikely that the immediate effects of chocolate stem from a direct effect on neurotransmitter levels or theobromine and caffeine in the chocolate. The article proposes that the immediate effect may stem from the large amount of fat and sugar in chocolate.

Another related review- article, called Mood-state effects of chocolate [3], by Gordon Parker et al suggests that chocolate, may, despite its ephemeral effects affect various neurotransmitter systems, contributing to an effect on appetite, reward and mood-regulation.

Most significantly, the article suggests that while serotonin (5-HT) biosynthesized from the amino acid tryptophan may affect carbohydrate craving, the correlation isn’t entirely clear. The article suggests that while serotonin may be involved, carbohydrate indigestion have been found to exhibit mood-changes without altering serotonin activity.

Moreover, the fact is, that chocolate may exhibit its effects through taste-preference for sugar and fat ratios. Chocolate has very appealing sensory characteristics, high fat and sugar with an attractive flavor and aroma. This may also be the reason for the addictive potential of chocolate. The exact sensory combination of fat, sugar, flavor and aroma in chocolate, is not found elsewhere, and may be impossible to replace. Looking at chocolate addiction from an evolutionary perspective, humans have always had innate taste preferences for sweet, fat and salt. This was a mechanism that ensured humans to survive by providing sufficient calories and nutrients.

Furthermore, the article [3] stresses that while chocolate affects negative mood, having a comforting role and eliminating dysphoria, it may actually prolong the process and not abort it. Due to the ephemeral characteristics of chocolate, it can’t, despite some claims, be denoted an antidepressant.

In conclusion, chocolate is a great drug for some immediate-gratification effects, but is a horrible antidepressant, despite the fact that it may affect various biogenic systems, including dopamine, serotonin, noradrenergic and opiate signaling.

Better go get myself some chocolate!

References

1. K Bruinsma and D L Taren, “Chocolate: food or drug?,” Journal of the American Dietetic Association 99, no. 10 (October 1999): 1249-1256.

2. Michael Macht and Jochen Mueller, “Immediate effects of chocolate on experimentally induced mood states,” Appetite 49, no. 3 (November 2007): 667-674.

3. Gordon Parker, Isabella Parker, and Heather Brotchie, “Mood state effects of chocolate,” Journal of Affective Disorders 92, no. 2-3 (June 2006): 149-159.

Categorized under Drugs & Chemicals

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