Sweet Medicine: The science of chocolate and health



Chocolate had used as medicine since its inception. The Aztec king Montezuma is said to have consume anywhere from 20 to 50 glasses in order to remain virile. In more recent times, scientists have been looking into whether there are some medical treasures hidden in this scrumptious treat. Naturally, scientists have been zooming in on what it is in chocolate that gives it its health benefits. Scientists now believe these compounds in chocolate, called flavanols, have antioxidant properties and could help treat a variety of conditions and fight a variety of diseases. This has led to a lot of good research being done. There have been studies done that look at chocolate’s impact in fighting heart disease, diabetes, and cancer[1]. There have been studies looking at chocolate’s effect on cognitive function, memory, and blood pressure.  However, before you run to the pantry to self-medicate with chocolate be forewarned; this research, like all medical research, in fact like all science, has caveats. This particular group of research has a good deal of caveats, though not every study has the exact same caveats. Those depend on the strengths and failings of each individual study.

There is one caveat though that applies to this entire group of research; all the chocolate in these studies is all dark chocolate, that is to say to that it is at least sixty percent cacao solids. Milk chocolate is not included and for good reason. US law states that chocolate only needs to contain ten percent cacao in order to legally qualify as chocolate, the rest is mainly sugar, fat, and a few other things such as milk. According to professor Carla Martin, lecturer at Harvard University and director of the Fine Cacao and Chocolate Institute, “A Hershey’s Kiss typically contains about, I think, 11 percent cacao content”. To put that in perspective, if you had a bar of typical milk chocolate that weighed one hundred grams (about the weight of an iPhone 5S[2]), then the actual amount of chocolate in the bar would be only about ten grams, or the weight of two nickels. The fact that milk chocolate has barely any actual chocolate means that milk chocolate has barely any of those cacao flavanols that are thought to provide the health benefits. Thus, anyone, scientist or otherwise, looking towards chocolate for health benefits has to look towards chocolate with a high cacao content.

Chocolate flavanols table
Figure 1


There are many pitfalls a research study can fall into. One of these is having a limited and/or small sample size.  Multiple studies on the effect of chocolate on health have had sample sizes of less than a couple hundred people. One such study, the Cocoa, Cognition, and Aging (CoCoA) Study had only ninety participants. The study found that regular cocoa flavanol consumption can reduce some measures of age-related cognitive dysfunction, but given such small sample size it is difficult to draw any large generalized conclusions for the general population, since there is a wide variety of differences across populations. Moreover, the CoCoA study limited their sample size in an attempt at prove clearer causation; because this was a study on aging all the participant were elderly, and the study also excluded Current smokers, habitual users of antioxidant supplements (including vitamins C and E), habitual consumers of chocolate or other cocoa products (daily consumption of any amount), or individuals prescribed medications known to have antioxidant properties (including statins and glitazones) or to interfere with cognitive functions (including benzodiazepines and antidepressants). This means for populations outside the participant group, the research has limited application, since the researcher did not look at how cocoa flavanol intake affects people with these additional variables. It has to be remembered that studies like this are jumping off point, they prove that there is something there that needs to be looked into, but further research is required in order to the proper applications and implications of the initial research.

Another caveat the research of chocolate health benefits is industry funding. Chocolate industries like Mars and Hershey have a lot of vested interest in having research completed that demonstrates that their product, that is to say chocolate, is healthy; especially in the increasing health consciousness of today’s America. These industries also affect what research gets done by funding one study over another. Rigorous research studies are expensive though, so it makes sense that scientist would accept funding from these multi-billion dollar corporations. This is not to say that industry funded research only produces bad or poorly done science. There is a large-scale clinical trial currently underway, the COcoa Supplement and Multivitamin Outcomes Study or ‘COSMOS’ study, in which half of the participants will be given cocoa extract capsules filled to take daily and the half will take a placebo, to meticulously test whether cocoa flavanols do reduce risk of heart attack, stroke, cognitive decline and many other health conditions over time. This study has the added advantage of removing all the fat and sugar from the chocolate, so the scientist can really see if it is the flavanols that are causing the benefits. Industry funded research just needs to be taken with a grain of salt. The chocolate industry is not interested in funding research into the side effects of chocolate consumption, after all, their vested interest is in trying to sell chocolate to people; but it is of the upmost importance that we have that knowledge so we can make informed decisions about the medical applications and implications of chocolate.

Something else that has to be in mind is that the amounts of flavanols in chocolate is really tiny. In many of the clinical trials participants were given much high doses of cocoa flavanols than what would typically be found in the average supermarket chocolate bar.  Just eating a piece of dark chocolate before bed won’t have the same effect.  There have been studies on the Kuna people, an indigenous people who live on islands off the coast of Panama, proposing that the reason that the Kuna who live on the island have lower blood pressure than their mainland counterparts is that the island-dwelling Kuna drink somewhere between eight and fifteen cups of unsweetened cocoa a day. If you were to have an equivalent number of chocolate bar per day, the amount of sugar and fat that would be added to your diet would quickly become hazardous to your health. For reference, to get the amount of the high concentration of cocoa flavanols use in the CoCoA study (993 mg) you would need to eat[3] about 6.29 ounces of dark chocolate (resulting in about additional 993 calories) or about 3.31 pounds of milk chocolate (resulting in approximately 7,745 additional calories).

Another issue scientists have to grapple with is that, “[…] from the chemical point of view, by itself chocolate is an incredibly complex substance” (Cole 31). Not only are there flavanols in chocolate, but there are also compounds called polyphenols and catechins as well as the stimulants caffeine and theobromine, all doing their own thing once they enter the body. Naturally this makes trying to figure out the causation of chocolate’s proposed health benefits a bit like trying to untangle a huge pile of yarn. This is one of the things that makes studies like the COMOS study so important; they try to extract the compounds from chocolate that they think are providing the health benefits and then test the effect of those, instead of testing the effect of a whole cup of cocoa or bar of chocolate. Scientists are still in the process of figuring out exactly what all these different chocolate compounds do in when they enter the body.

To find for causation for these effects, scientists have to limit the number of variables, so they exclude participants from doing things that would muddy their data, like for instance, eating foods rich in antioxidants or taking statins. Then they can go on to find, say that the consumption of cocoa flavanols consumption reduces blood pressure. The catch is that these scientists have only found that the consumption of cocoa flavanols consumption reduces blood pressure in people who don’t eat foods rich in antioxidants or take statins. For the people who do fall into the categories of eating foods rich in antioxidants or taking statins there is this tiny asterisk that says, we don’t know yet exactly how it affects you, and further research will need to be done in order to establish that. That is not to say the scientists have no idea, just that as more variables are added into the mix, cause and effect get a little murkier and it becomes harder to tell one from the other.

One of major shortcomings of this field of the science of chocolate health benefits is the lack of long-term studies. Many of the studies done on the health benefits of chocolate have only been of short-term duration. The CoCoA study, for instance, only last eight weeks. That type of study is great for determining causation or verifying the viability of possible applications for cocoa flavanols, but they don’t reveal the long-term effects of such treatments. It’s really common sense thinking, you need long term studies in order to learn the long-term effects. Knowing the long-term effects is important because there could be some side-effects that only shows up after two or three years of constant use. Scientists still aren’t completely sure how the body would react to prolonged exposure to high levels of cocoa flavanols over a period of many years. Long term studies are also important because not only do they verify the results of earlier, short term studies but they help determine how long the benefits of cocoa flavanols last once inside the body, which has important implications for any future medical applications of this research.

Though without a doubt one of the great caveats that the science of chocolate health benefits has is that people are not lab mice. People do not live in environments carefully managed by scientists. People live in all sorts of complex environments with countless factors affecting their health, from air and water quality to noise level. People have all sorts of diets and as Sophie and Michael Coe said, “[a]nother complication is that we mortals take into our digestive systems all kinds of other foods, before, during, and after consuming chocolate, so that these variables should be taken into consideration” (Coe 31). The previously mentioned Kuna people may have gotten their lower blood pressure due to their cocoa drinking habit, but it also might be due to the low pollution environment in which they live or the rest of their diet, which is higher in fruit and fish and lower in fat and processed foods than their more urban mainland counterparts or a combination of these and a variety of other factors. There also the emerging field of the microbiome and as scientist delving further in, they are discovering new things about how what people eat affect their microbiome and how a person’s microbiome affects how they react to what they eat. Since there is so much going on both outside people and inside, it’s hard to tell what the actual impact will when we add cocoa flavanols to this huge web of systems. Scientists are still figuring this one out.

In conclusion, the field of the health benefits of chocolate is still in its infancy. There are a lot of promising findings but there is still a lot of work to be done.  Be aware that scientific research always has caveats. Many people when they hear about the science of the health benefits of chocolate think that it means that they can eat as much chocolate as they want. Comedian Josh Sharp when he heard about that said, “that would be like, should I take my medicine inside a stick of butter?” and compared it to “[taking] two ibuprofen and down it with a gallon of cream” (Expert 0:22:39).  So no, you still can’t eat all the chocolate you want to. Moderation, like in all things, is key. A little bit of chocolate won’t hurt you, just don’t overdo it; and next time you decide to have a little piece of dark chocolate you don’t have to feel so guilty.




Work cited

Coe, Sophie D. and Michael D. Coe. The True History of Chocolate. Third Edition. Thames & Hudson Ltd: London, 2013. Print.

Howe, James. 2012. “Chocolate and Cardiovascular Health: The Kuna Case Reconsidered.” Gastronomica: The Journal of Food and Culture 12 (1) (May 1):

Watson, Ronald Ross, Victor R. Preedy, and Sherma Zibadi, eds. 2013. Chocolate in Health and Nutrition. pp. 265-276

Mastroiacovo, Daniela, et al. “Cocoa Flavanol Consumption Improves Cognitive Function, Blood Pressure Control, and Metabolic Profile in Elderly Subjects: the Cocoa, Cognition, and Aging (CoCoA) Study–a Randomized Controlled Trial.” The American Journal of Clinical Nutrition, vol. 101, no. 3, 2015, pp. 538–48.

Benton, David. 2004. “The Biology and Psychology of Chocolate Craving.” pp. 205-218

Aubrey, Allsion. “A Chocolate Pill? Scientists To Test Whether Cocoa Extract Boosts Health”. NPR’s the salt. August 29, 2016.

Graber, Cynthia and Twilley, Nicola. (2017, Jan 30). “We Heart Chocolate”. Gastropod. Podcast retrieved from https://gastropod.com/we-heart-chocolate/

Duffy, Chris. (2016, April 22). “Medicinal Chemistry at the Atlanta Science Festival”. You’re the Expert. Podcast retrieved from http://www.stitcher.com/podcast/youre-the-expert/e/45268625?autoplay=true

Zukerman, Wendy. (2017, May 4). “Chocolate, Coffee and Wine”. Science Vs.  Podcast retrieved from https://gimletmedia.com/episode/chocolate-coffee-and-wine/

Image and video credits

(in descending order)




“Flavonols in cocoa may boost brain function, study shows”. YouTube, uploaded by CBS This Morning,  Oct 27, 2014

“Why eating chocolate is good for you”. YouTube, uploaded by The Economist, Feb 12, 2015.

“The AMAZING Benefits Of Dark Chocolate!”. YouTube, uploaded by Seeker,  Jul 9, 2014.



[1] Watson et. al. 271

[2] Courtesy of iphonefaq.org


[3] all numbers based on the table in Figure 1, which uses the average amount of chocolate consumption required to reach 750 mg of flavanols. As such all resulting calculations are a bit rough.

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