Opinion, Berkeley Blogs

Chocolate: for Valentine's Day

By Rosemary Joyce

Valentine's Day: for many people this brings gifts of chocolate.

Not that chocolate gift giving is recession proof.

A 2009 article from Nielsen market research predicted that sales of chocolate for Valentine's Day would reach $345 million, enabling purchase of 58 million pounds of chocolate. But in 2010, the National Retail Federation found that couples were cutting back plans for Valentine's Day spending by 5%. And chocolate wasn't the first choice of men or women: more men planned to give flowers or cards than candy, while women were more likely to plan on giving cards. Still, even that report predicted that 48 million pounds of chocolate would be sold in the week leading up to Valentine's Day.

Still, despite politics and simple supply-and-demand both conspiring to drive up prices for chocolate, spending on Valentine's chocolate in 2011 is expected to rise to $937 million-- just shy of one billion dollars-- this year.

Increasingly we are told that chocolate does more than make you feel good; it can help keep you healthy.

In the latest in a long line of similar research reports, a German study of almost 20,000 people tracked for ten years found that eating the equivalent of one square of dark chocolate a day was associated with lower blood pressure and decreased risk of heart attack. Previous studies showed similar benefits for circulatory system health, blood pressure, insulin sensitivity and blood clotting. All studies stress that the highest health benefits of chocolate come from the least processed form, dark chocolate, which brings more chocolate compounds and less added sugar.

But chocolate has been celebrated for making people feel good long before the recent surge of medical research. Just why has been a subject of other research, on chocolate chemistry.

Among the suite of chemicals chocolate contains are traces of anandamide, a chemical that binds to the same receptors in the brain that respond to cannabinoids- the active chemicals in marijuana. Also present is tryptophan, which leads to the production of serotonin, a neurotransmitter that improves mood and encourages relaxation. Chocolate contains low concentrations of phenylethylamine, an amphetamine-like chemical linked to the release of dopamine. Another similar chemical in chocolate is tyramine. Finally, eating chocolate triggers the release of endorphins in the brain, leading to feelings of well-being. Most of these chemicals are found in very low concentration, but they are remarkably consistent in their biological effects with the good feelings chocolate lovers ascribe to their drug of choice.

My own research on chocolate origins has been most indebted to another chemical compound: theobromine. Named after the genus of the cacao plant, Theobroma cacao ("cacao, food of the gods"), theobromine is a methylxanthine, related to caffeine (which is also present in the cacao plant).

Theobromine is the key to identifying cacao residues in archaeological sites in the Americas where the cacao plant (or its relative, Theobroma bicolor) was in use. When found outside the natural range of related plants in northern South America, theobromine means cacao. This has made it possible for researchers in Central America to detect chocolate use, despite the fact that the plant is entirely destroyed in the process of preparation and consumption.

By using water, alcohol, and even chloroform to dissolve chemicals deposited in the porous walls of pottery suspected of having been used to hold chocolate drinks, and subjecting the extracts to chemical analysis, we can tell when an empty bowl, bottle, or drinking cup once contained chocolate. Most recently, that allowed researchers to identify traces of chocolate in pots from Chaco Canyon, in New Mexico; far north of the area where the cacao plant grows, and far from the nearest known centers of cacao use.

So happy Valentine's Day! As you share chocolate with your loved one, think about the untold stories of chocolate that archaeologists, medical researchers, and chemists are working to discover for you.

Revised version of post on Psychology Today: What Makes Us Human