All About….Chocolate! (Need I Say More?)

In or out of love, I think anyone can appreciate the annual Valentine’s Day-induced chocolate craze. I recently learned that this week is officially chocolate week in New York City (makes sense). London also has a chocolate week, from the 8th to 14th of October (does not make sense). But, I mean, it’s chocolate. There doesn’t have to be a holiday or good reason to eat it.

Or does there?

Chemistry says that there is a reason to eat chocolate, or at least reasons we like to.

Chocolate has been claimed to have all kinds of effects on the body and mind, including being a stimulant, relaxant, euphoriant, aphrodisiac, tonic and antidepressant. That’s a pretty impressive resumé. Although there are about 380 compounds in chocolate, only a few have been identified as potential sources of our cravings (5). I always thought that caffeine was the main active compound found in chocolate, but apparently there are other chemicals that play much larger roles in its feel-good properties.

Some of these properties originate from a class of chemicals called methylxanthines. Methylxanthine is what caffeine, theobromine and xanthine are derived from, all of which are found in chocolate. Of the three, theobromine is the big player in chocolate. This study found that the average cocoa powder contains 1.89% theobromine and only 0.21% caffeine. In fact, one variety of cacao plant is actually called Theobroma Cacao (a name derived from Greek meaning, “food of the Gods.” Seems appropriate.). Another study compared how much volunteers’ preferences increased for a mystery drink plus placebo pill, versus a mystery drink plus methylxanthine-containing pill. They found that the drink paired with the chemical was significantly better liked over the course the experiment. The prescence of these compounds must have something to do with our craving for chocolate. So, what exactly is this magical theobromine?

A Theobroma Cacao tree….give thanks.

Theobromine is an alkaloid. Alkaloids are basic compounds that usually contain a Nitrogen atom, and a ring in their structure. They’re often associated with poisonous or addictive things, like nicotine and morphine (because they are also examples of alkaloids) (1). Alkaloids are the reason that dark chocolate tastes a little bitter (see also: black coffee). But, don’t let its alkalinity scare you off.

Like caffeine, theobromine is found in coffee and tea in smaller amounts than in cacao products. In fact, caffeine and theobromine have very similar molecular structures. The only difference is that one molecule (theobromine) has a Hydrogen atom (H), and the other (caffeine) has a methyl group (a Carbon attached to four Hydrogens) on the end (2). Similar molecular structures mean they do some of the same stuff to your brain, like make you more alert (5). Weirdly enough, theobromine lowers blood pressure whereas caffeine actually increases blood pressure (3). So, similar, but not the same. Our brains are very particular (thank goodness).

[Total Side Note: Research is being done to see if theobromine consumption is an effective treatment for asthma symptoms because theobromine is also a cough suppressant (4). I’ve been wondering since I read that if being sick is an excuse to eat lots of chocolate. Then again, most things are excuses for eating chocolate.]

It’s no coincidence that chocolate is craved by women more than any other food, and the average American eats 11 pounds of the stuff each year (5). This article from CNN health provides some interesting hypotheses about chocolate and mood. A compound called anandamide (a.k.a. the “bliss molecule”) is found in chocolate. It activates some of the same parts of the brain that marijuana does (the part that makes dopamine), but to a much smaller degree. Not only does it contain this chemical, but researchers from the Neuroscience Institute of San Diego suspect that some components of chocolate prevent feel-good anandamide from breaking down in the brain. In addition to speculation about the anandamide content of chocolate, scientists have studied the effects of chocolate on serotonin levels in the brain.

Serotonin is a neurotransmitter, which is any molecule that carries messages through your brain, such as when it’s bedtime or how happy you feel. Specifically, low levels of serotonin can cause depression. One chemical in chocolate (tryptophan) causes the brain to release extra serotonin, which generally results in a better mood. Personally, I’m skeptical that it may just improve my mood because it is delicious.

Finally, chocolate also contains a chemical called phenylethylamine. It’s related to amphetamines.  Phenylethylamine is similar to amphetamines in that consuming it results in lower blood pressure and higher blood-sugar levels. This makes you feel more alert, fine, and dandy.  It also makes you feel like you’re in love as a result of a quickened pulse (5). Just in time for Valentine’s Day <3

It’s been a month since New Year’s, right?

There’s the evidence. As if the taste wasn’t enough……

I hope you enjoyed this post on the chemicals in chocolate : ) Please leave comments or questions, and enjoy some hot cocoa before it’s too warm.

 

-Ashley

 

Bonus! A chemistry activity website for your spare time: http://pbskids.org/zoom/games/kitchenchemistry/index.html

 

Sources

(1) http://www.thefreedictionary.com/alkaloid

(2) http://www.hersheys.com/nutrition-professionals/chocolate/composition/caffeine-theobromine.aspx

(3)http://www.sciencedirect.com/science/article/pii/S0031938411003799

(4) http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/theobromine.asp?playpodcastlinkuri=%2Fchemistryworld%2Fpodcast%2FCIIEcompound.asp%3Fcompound%3DTheobromine

(5) http://faculty.washington.edu/chudler/choco.html