Most of us are well aware that chocolate is already a bit addictive to human beings... maybe it's the caffeine or the sugar? But what if there were a species to which chocolate was as addictive as heroin? Not only is it the best smelling/tasting and enticing thing they've ever encountered, but the first time they try it, they are instantly hooked. Attempting to forgo chocolate results in severe withdrawal symptoms. However, other human sweets/foods do not cause this, unless there is chocolate in them. Only chocolate, specifically. Other than the cravings, withdrawals, and a surge of "happiness" upon consuming chocolate (endorphins, probably), chocolate doesn't have any other typically associated drug-like effects such as hallucinations or motor function impairment.

What could be causing this phenomenon? Assuming the species functions under the same basic physiological systems we generally understand in life as we know it, as opposed to being a weird fifth-dimensional crystalline-based goo being or some other fantasy dodge. Is there any way to explain or justify this extreme addictive effect?


2 Answers 2



Theobromine...is a bitter alkaloid of the cacao plant...It is classified as a xanthine alkaloid, others of which include theophylline and caffeine. The compounds differ in that caffeine has an extra methyl group. (ref)

While smaller amounts of theobromine can be found in other foods (like tea) and caffeine can break down into theobromine, the largest source is from chocolate.

Theobromine is not considered addictive in humans, but it certainly does have some effects.

The contributions of theobromine are less clear and its psychoactive effects appear subtle...Although two early studies failed to detect psychopharmacological activity...[one] found that 5 of 7 participants were able to discriminate 560 mg theobromine from placebo or caffeine, suggesting that theobromine might be about one tenth as potent as caffeine. While theobromine did not significantly increase any subjective or behavioral measures...when all subjects were combined, the compound increased alertness, headache, and irritability in some individuals, suggesting the possibility of individual differences in sensitivity. Using a higher dose, [one study] found that 700 mg theobromine lowered blood pressure, decreased self-report calmness and increased subjects' ratings of how interesting they found performance of study tasks. (ref)

Your aliens may have biochemistry where theobromine leads to dopamine staying active for longer than normal. Like cocaine does in humans.

The brain’s mesolimbic dopamine system, its reward pathway, is stimulated by all types of reinforcing stimuli, such as food, sex, and many drugs of abuse, including cocaine... Besides reward, this circuit also regulates emotions and motivation.

In the normal communication process, dopamine is released by a neuron into the synapse (the small gap between two neurons), where it binds to specialized proteins called dopamine receptors on the neighboring neuron. By this process, dopamine acts as a chemical messenger, carrying a signal from neuron to neuron. Another specialized protein called a transporter removes dopamine from the synapse to be recycled for further use.

Drugs of abuse can interfere with this normal communication process. For example, cocaine acts by binding to the dopamine transporter, blocking the removal of dopamine from the synapse. Dopamine then accumulates in the synapse to produce an amplified signal to the receiving neurons. This is what causes the euphoria commonly experienced immediately after taking the drug. (ref)

In fact, all additive drugs work in similar ways.

All drugs of abuse, from nicotine to heroin, cause a particularly powerful surge of dopamine in the nucleus accumbens. The likelihood that the use of a drug or participation in a rewarding activity will lead to addiction is directly linked to the speed with which it promotes dopamine release, the intensity of that release, and the reliability of that release. Even taking the same drug through different methods of administration can influence how likely it is to lead to addiction. Smoking a drug or injecting it intravenously, as opposed to swallowing it as a pill, for example, generally produces a faster, stronger dopamine signal and is more likely to lead to drug misuse. (ref)

I see a future of cacao crack and mainline milky ways.

In seriousness though, different species react in different ways to the same substances. The same amount (adjusted by weight) of chocolate that leads to pleasure for humans will kill a dog or a cat.

Theobromine is toxic to a dog when it ingests between 100 and 150 milligrams per kilogram of body weight...It would take 20 ounces of milk chocolate to kill a 20-pound dog, but only 2 ounces of baker's chocolate or 6 ounces of semisweet chocolate. (ref)

So, for your aliens, theobromine has an addictive effect. Chocolate being the easiest and tastiest way to get it.

  • 2
    $\begingroup$ Learnt a lot here, nice informative and logical answer $\endgroup$
    – Kilisi
    Apr 14, 2019 at 9:26
  • $\begingroup$ Interesting, thanks. Potentially a solid solution. What other foods is theobromine found in? If it's common I would worry about making too many foods into drugs, haha. $\endgroup$
    – MarielS
    Apr 14, 2019 at 19:37
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    $\begingroup$ @MarielS It is in smaller amounts in tea (real tea, not herbal) and cola nuts. myfooddata.com/articles/chocolate-high-in-theobromine.php $\endgroup$
    – Cyn
    Apr 14, 2019 at 19:41
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    $\begingroup$ @Cyn That's not too many "affected" foods; sounds like a good fit! I'll leave the question around a bit to see if it attracts any other answers. After a day or two I'll probably accept this one. Really informative, thank you. $\endgroup$
    – MarielS
    Apr 14, 2019 at 19:45

@Cyn has a great answer, and I would add that Theobromine is also being used in toothpastes and other products because of it's unique properties.

Aside from Theobromine, and looking at the manufacturing side of chocolate, I might recommend also:

Ammonium Phosphatide

Ammonium Phosphatide is a type of salt approved for use in the USA as well as the EU. It operates like lecithin (that is, as an emulsifier), and is usually manufactured from rapeseed oil. You can read a detailed description of this in this paper, which focuses on it's use in chocolate production.

Like many types of salts, it's addictive "just like cigarrettes and hard drugs" because of how it interacts with the brain. As such, it is not unfathomable to consider an organism with a brain that interacts with this specific type of salt in a way similar to heroin.

  • $\begingroup$ + 1 for creativity! $\endgroup$
    – pHred
    Apr 15, 2019 at 2:16

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