Nurturing The Brain – Part II, Chocolate




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Chocolate refers to anything that is made from cacao beans. The word “chocolate” has been etymologically traced to the Aztec word “xocoatl,” which referred to a bitter drink brewed from cacao. It’s thought to have been cultivated by different cultures in central and south America for at least 3,000 years. The scientific name for cacao was given by the Swedish botanist Carl Linnaeus in 1753, when he published his book Species Plantarum. Linnaeus must have loved chocolate for he named it Theobroma cacao, meaning “food of the gods” in Latin. Chocolate clearly brings a lot joy to the world. But why?

Chocolate is so widely loved that it has even motivated some funny articles published in the humorous sections of well known medical journals. In 2012, an article entitled Chocolate Consumption, Cognitive Function, and Nobel Laureates was published in the Occasional Notes section of The New England Journal of Medicine. It established a striking correlation between chocolate intake per capita and the number of Nobel laureates in various countries. The study was obviously a joke, with data being obtained, as clearly stated, from Wikipedia and chocolate manufacturers’ websites. But still, it caused intense debate!

But my favorite one was published in 2007 in the Canadian Medical Association Journal (CMAJ). The “study”, designed to compare the effects of dark chocolate, milk chocolate and “normal” chocolate consumption on happiness, was deemed inconclusive after it was found that the control group, who received no chocolate, had decided to start raiding the chocolate of those in the other groups. Even though it was entitled the Chocolate Happiness Undergoing More Pleasantness (CHUMP) study, some people still believed it!

There are many pleasure-inducing and stimulating compounds found in chocolate that can increase the availability of dopamine, serotonin and endorphins thereby making you feel good. Some of them could potentially even make you high!

First off, the most consumed stimulant in the world, caffeine, occurs naturally in chocolate, and I’ve told you about the effects of that substance already.

Chocolate also contains cannabinoid-like fatty acids that are pharmacologically related to anandamide. Anandamide is the endogenous brain cannabinoid that acts on cannabinoid receptors and modulates the dopaminergic reward system increasing pleasure. These cannabinoid-like fatty acids found in chocolate may act by directly activating the cannabinoid receptors or by increasing anandamide levels through inhibition of its metabolism, thereby inducing a sensation of euphoria.

Phenylethylamine, colloquially known as the “love drug”, is another pleasure-inducing substance present in chocolate. It is structurally and pharmacologically similar to amphetamine. This compound is also endogenously produced by the brain where it increases the availability of dopamine and noradrenaline; it is an important modulator of mood and its deficit has been associated with the pathogenesis of depression.

Although these mood-lifting substances could potentially account for the pleasure obtained from eating chocolate, their concentration in (a reasonable amount of) chocolate is probably insufficient for such neurochemical effects. There is actually more phenylethylamine in cheese and sausages.

The pleasure obtained from chocolate may actually be derived from its orosensory properties, such as flavor and smell. These appealing properties have a significant influence over eating and these characteristics and the sensory gratification they bring may be sufficient to explain the craving for chocolate just by seeing it (and maybe reading about it).

Aside from pleasure, the positive effects of chocolate have been reported for a wide variety of health conditions. Chocolate is a rich source of flavonoids, mainly flavanols, which are potent antioxidant and anti-inflammatory agents. Flavonoids can act in brain regions involved in learning and memory, especially the hippocampus. There is strong evidence that chocolate, due to its flavonoid content, has long lasting neuroprotective effects for neurodegenerative and neuroinflammatory disease.

The neurobiological effects of flavanols are believed to occur by direct promotion of neurogenesis through the expression of neuroprotective and neuromodulatory proteins which regulate neuronal function and brain connectivity. Flavonols, whose cardiovascular beneficial effects are well-known, may also improve blood flow and angiogenesis (the formation of new blood vessels) in the brain. Protective effects of long-term flavanol consumption have also been shown in animal models of normal aging, dementia, and stroke. Human studies have provided evidence for a positive effect of cocoa flavonoids on vision, cognition, learning, memory, mood, and reduced cognitive decline in aging and Alzheimer’s disease.

Theobroma, food of the gods indeed.

References

Bruinsma K, & Taren DL (1999). Chocolate: food or drug? Journal of the American Dietetic Association, 99 (10), 1249-56 PMID: 10524390

Chan K (2007). A clinical trial gone awry: the Chocolate Happiness Undergoing More Pleasantness (CHUMP) study. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 177 (12), 1539-41 PMID: 18056618

Messerli FH (2012). Chocolate consumption, cognitive function, and Nobel laureates. The New England journal of medicine, 367 (16), 1562-4 PMID: 23050509

Parker G, Parker I, & Brotchie H (2006). Mood state effects of chocolate. Journal of affective disorders, 92 (2-3), 149-59 PMID: 16546266

Scholey A, & Owen L (2013). Effects of chocolate on cognitive function and mood: a systematic review. Nutrition reviews, 71 (10), 665-81 PMID: 24117885

Sokolov AN, Pavlova MA, Klosterhalfen S, & Enck P (2013). Chocolate and the brain: neurobiological impact of cocoa flavanols on cognition and behavior. Neuroscience and biobehavioral reviews, 37 (10 Pt 2), 2445-53 PMID: 23810791

Image via Vladislav Gudovskiy / Shutterstock.

Sara Adaes, PhD

Sara Adaes, PhD, has been a researcher in neuroscience for over a decade. She studied biochemistry and did her first research studies in neuropharmacology. She has since been investigating the neurobiological mechanisms of pain at the Faculty of Medicine of the University of Porto, in Portugal. Follow her on Twitter @saradaes
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