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 “Dark Chocolate: Is it really “good” for you?”

Valerie Kuznik

 

April 4, 2010

 

 

 

 

 

Introduction

 

          In the past few years, dark chocolate has been gaining attention in both academic and popular discussion for its alleged health benefits. The phrase “dark chocolate is good for you!” seems to increase in prevalence as the years pass, but one rarely stops to take a moment to wonder, is dark chocolate really good for you? What are the properties dark chocolate that makes it “good,” and how does they specifically help the body? After online research in academic databases and websites and careful analysis of peer reviewed studies, it is apparent that dark chocolate sits in a gray area between “good” and “bad;” though dark chocolate offers considerable health benefits, specifically for the cardiovascular system, it is not without its drawbacks.

dove_dark_chocolate_bars.jpg

 

 

 

 

 

 

 

http://candyaddict.com/blog/2007/12/05/candy-review-doves-extra-dark-and-single-origin-chocolates/

 

 

Properties of Dark Chocolate

 

          Dark chocolate, like milk chocolate, comes from the Theobroma cocoa tree (http://www.finedarkchocolate.com). However, dark chocolate is unique because it contains the flavonoid (defined as a type of pigment in plants by the Oxford American Dictionary) epicatechin (http://www.webmd.com/diet/news/20040601/dark-chocolate-day-keeps-doctor-away). Flavonoids, types of antioxidants, resist damage to cells normally caused by free radicals (http://my.clevelandclinic.org/heart/prevention/nutrition/chocolate.aspx), which are tissue-damaging molecules (http://www.aarp.org/health/conditions/articles/harvard__a-guide-to-alzheimer-s-disease_13.html). When free radical damage is not prevented, it can lead to a build up plaque on the walls of arteries (http://my.clevelandclinic.org/heart/prevention/nutrition/chocolate.aspx), which is why the consumption of dark chocolate is arguably a cardiovascular preventative measure. Although it is apparent that antioxidants in general offer health benefits, epicatechin specifically reduces blood clotting (http://www.phytochemicals.info/phytochemicals/epicatechin.php, http://www.medilexicon.com/medicaldictionary.php?t=69598) and the production of free-radicals (http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def-L/lipid_peroxidation.html).  Thus it is clear that the epicatechin found in dark chocolate is considerably beneficial to one’s health.

          But why is there a distinction between the health benefits of dark chocolate and those of white and milk chocolate? According to the Cleveland Clinic Miller Family Heart and Vascular Institute, processing is to blame. All chocolate must be processed to some degree because cocoa originally has a very strong taste that must be dulled for consumption. While this processing improves the taste, it actually decreases the amount of flavonoids present in the chocolate. Dark chocolate is processed the least compared to white and milk and seems to maintain the greatest amount of flavonoids through this processing (http://my.clevelandclinic.org/heart/prevention/nutrition/chocolate.aspx).

          In addition to benefitting the vascular system of the body, dark chocolate is beneficial elsewhere as well. Aside from its great taste, it activates the production of endorphins, which are neurotransmitters that dull one’s sense of pain (http://www.medicinenet.com/script/main/art.asp?articlekey=55001). In addition, dark chocolate is a source of serotonin (anti-depressant) and offers energy in the form of theobromine and caffeine (http://longevity.about.com/od/lifelongnutrition/p/chocolate.htm)

chocolate-ripe.jpg

 

 

 

 

 

 

 

 

Theobroma Cocoa Tree, http://static.howstuffworks.com/gif/chocolate-ripe.jpg

 

Scientific Studies

         

          To what degree and how dark chocolate is beneficial to one’s health is explored in the following peer review studies, which further prove dark chocolate’s varying health benefits.

          The first study, “Dark chocolate improves endothelial and platelet function,” was performed by cardiovascular doctors from University Hospital in Switzerland and demonstrates the benefits of dark chocolate. The studied aimed to answer the following question: what is the effect of consuming dark chocolate (rich in polyphenol) on “endothelial and platelet function” (Hermann, Spieker, Ruschitzka, Sudano, Hermann, Bingelli, Luscher, Riesen, Noll, Corti, 2006)? The study involved the participation of twenty male smokers, as smoking cigarettes causes “endothelial dysfunction” (Hermann et al., 2006), which is related to most cardiovascular diseases. As a result, the subjects were ideal for determining the effect of dark chocolate on endothelial and platelet function. Endothelial cells line blood vessels (http://www.biology-online.org/dictionary/Endothelial_cells) and platelets are cells necessary for clotting blood (http://www.medterms.com/script/main/art.asp?articlekey=4941).  The twenty men were broken up into two random groups: one group was given forty grams of dark chocolate and the other was given forty grams of white chocolate. Following this consumption, the brachial artery was measured using ultrasound for “flow mediated dilation” (Hermann et al., 2006) (FMD), meaning that the scientists were measuring how dilated a blood vessel became as there was an increase in blood flow through it (Kelm, 2002). These measurements were taken at two, four, eight, and twenty-four hour marks. The study found that the men who had consumed the dark chocolate had a much better FMD in comparison to the baseline, while white chocolate did not impact FMD. As a result, it was concluded that dark chocolate does indeed have a positive effect on endothelial and platelet function, demonstrating a benefit of dark chocolate consumption, especially in comparison to other types of chocolate (specifically white). However, the study did raise the question about long-term effects of consumption and the unknown implications of such behavior, as the study only covered at maximum a twenty-four hour time period (Hermann et al., 2006).

study one.tiff

(Hermann, Spieker, Ruschitzka, Sudano, Hermann, Bingelli, Luscher, Riesen, Noll, Corti, 2006).

 

          A very unique study, “Does Flavanol Intake Influence Mortality from Nitric Oxide-Dependent Processes? Ischemic Heart Disease, Stroke, Diabetes Mellitus, and Cancer in Panama,” was conducted by Vincente Bayard, Fermina Chamorro, Jorge Mott and Norman K. Hollenberg, all highly qualified scientists holding various faculty positions in universities in Panama as well as at Harvard Medical School (Norman K. Hollenberg). This study focused on the Kuna people of San Blas, an island near Panama. The San Blas people are unique in that they consume the greatest amount of cocoa of any population, as a cocoa drink is their primary beverage. Additionally significant is the fact that this cocoa is grown by the people and therefore is unprocessed, unlike cocoa found in stores elsewhere would be. The study involved the comparative analysis of the cause of death on death certificates from 2000 to 2004 of 548 people from San Blas and 77,375 from the Panamanian mainland.  Using this information, the “frequency of deaths per hundred thousand population” (Bayard, Charmorro, Motta, Hollenberg, 2007) was calculated for different causes of death, and these calculations were tabulated both crude and age-adjusted. The results showed the leading cause of death in mainland Panama to be circulatory diseases while that of San Blas was found to be infections. Even more significantly, the San Blas population demonstrated very low frequencies of death caused by cancer, stroke, diabetes and heart disease. There are several limitations to this study. First, the technology available to the Kuna Indians not great, and therefore the autopsies to determine the cause of death may not have been as accurate as possible. Thus, the frequency of causes of death may have been affected. However, this limitation may be countered by the information that with the technology that is available to the Kuna’s, diagnosis of circulatory diseases and cancers has been extremely low. For example, out of the thousands of Pap smears in addition to biopsies performed each year for the past five years, there have been no cases of cervical cancer, which supports the accuracy of the cause of death frequencies despite the technology gap. Another limitation is the influence of other possible outside influences on the frequencies of death causes aside from the intake of cocoa, such as stress levels, air and water purity, diet, and smoking. Though some of these have very little comparative differences between San Blas and the mainland, others (such as smoking, where it is much less frequent on San Blas than the mainland) may have impacted the frequency of cause of death (Bayard et al., 2007).

San Blas Table.tiff

          (Bayard, Charmorro, Motta, Hollenberg, 2007)

 

Another study entitled “Dark chocolate consumption increased HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans” was conducted in Finland by faculty of the University of Kuopio and the Inner Savo Health Center. The studied aimed to answer the following question: what are the long-term effects of chocolate consumption on “serum lipids and lipid peroxidation” (Mursu, Voutilainen, Nurmi, Rissanen , Virtanen, Kaikkonen, Nyyssonen, Salonen, 2004)? Every day for three weeks, forty-five healthy, non-smoking, non-obese men and women who were not taking drugs nor supplements containing antioxidants consumed seventy-five grams of white chocolate, regular dark chocolate, or “cocoa polyphenol-enriched dark chocolate” (Mursu et al., 2004). In order to ensure that the results reflected effects of the dark chocolate alone, participants were asked to stop consuming red wine, chocolate, tea, and cocoa one week before the study began and to abstain until the study was over. The results of the study were measured by taking blood samples from participants and measuring for different levels of various proteins, fatty acids, and lipids. In the end, it was found in the groups given regular dark chocolate and enriched dark chocolate that the amount of HDL (high-density lipoprotein (http://wordnetweb.princeton.edu/perl/webwn?s=hdl cholesterol)) cholesterol increased and the “concentration of serum LDL diene conjugates, a marker of lipid peroxidation” (Mursu et al., 2004) decreased. However, this changes were not present in the group that consumed white chocolate, meaning they were most likely specifically caused by the cocoa in the dark chocolates (both regular and enriched). HDL cholesterol increase is beneficial (it is know as “good cholesterol” (http://heartdisease.about.com/cs/cholesterol/a/raiseHDL.htm)) because it helps clear out “bad” cholesterol (http://heartdisease.about.com/cs/cholesterol/a/raiseHDL.htm), while the increase in serum LDL diene conjugates, which means an increase in lipid peroxidation  (Mursu et al., 2004), is beneficial because lipid peroxidation prevents cell damage caused by free radicals (http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def-L/lipid_peroxidation.html). It is interesting to note that the amount of fatty acids in both the white and dark chocolates is the same, meaning that the increase in HDL cholesterol must have been caused by the cocoa alone. A limitation of this study was the lack of a no-fatty-acids-from-chocolate control group, meaning that the increase in lipid peroxidation may have been caused by something other than the fatty acids in chocolate. In the conclusion, the study warns of the probabitlity of weight gain from consuming large quantities of dark chocolate, a health detriment. It is interesting that the purpose of this study was to investigate the long term effects of consuming dark chocolate, which is a limitation of many studies (including the first study mentioned previously in this section) (Mursu et al., 2004).

 

Miracle Chocolate?

 

          Though it is evident that dark chocolate aids the cardiovascular system of the human body among other benefits for the body as a whole, one must be wary of lofty promises. Dark chocolate might be “good” for you, but it’s no miracle drug. 

The website “Outlive Your Doctor” begins by unbelievably stating its credibility as the following: “’based on the information and research I have on November 2007 the following makes sense to me,’ Harlan Jacobsen” (http://outliveyourdoctor.com/11.5.chocolate.shtml). It is almost impossible to take this website’s claims seriously after their one attempt at establishing credibility is nothing more than a generic statement offering no proof nor authority; it’s anyone’s guess who Harlan Jacobsen and his credentials are missing from the site. This site’s article “The Dark Chocolate Miracle” claims that dark chocolate “beats any magic pills at the drug store,” and calls their article about dark chocolate to be “the greatest thing…every (sic) published” (http://outliveyourdoctor.com/11.5.chocolate.shtml).  Instead of citing specific studies, the article generically refers to “dozens of studies” and seems more concerned with instructing readers to consume Hershey’s dark chocolate each day than explaining why (http://outliveyourdoctor.com/11.5.chocolate.shtml). This website’s dark chocolate claims are extreme and clearly not credible, provided one can move past the egregious spelling mistakes and lack of any specific citations.

Another website, “The Dark Chocolate Miracle,” again seems to make claims not justified by science. To begin with, the website is clearly commercial, as they are attempting to sell their product Tru Chocolate. As a result, it is likely that any information they provide is biased at best, because it is in their own self interest that readers believe in the benefits of dark chocolate and therefore buy their product. This site claims that their product is “guilt free chocolate” and “the most healthy…chocolate ever created”  (http://www.darkchocolatemiracle.com). Whether or not these claims are true is one matter, but another one all together is that aside from the website URL, it is difficult to find a correlation between dark chocolate and their chocolate. Unbelievably, it is not listed anywhere that this chocolate is even partially dark chocolate. No less, the founder of the company, Dr. Joel Wallach, has a veterinary degree and received a degree from the National College of Naturopathic Medicine, meaning he does not have a medical degree and therefore his authority is questionable (http://www.darkchocolatemiracle.com) at best.

To conclude, though dark chocolate can be beneficial, one must still be careful to recognize false claims and exaggerated benefits of dark chocolate consumption, especially from sources lacking authority and scientific support.

 

The Thorn of the Rose: Negative Effects of Consumption

 

          Dark chocolate is still chocolate, so one should never simply begin binging on it while thinking they are doing it in the good name of their health. In an article about dark chocolate benefits, the well-credited Cleveland Clinic warns that although small amounts of dark chocolate can be consumed “guilt-free,” one must remember that something does not become magically healthy once it is dipped in dark chocolate; a marshmallow is still just as fattening with or without a dark chocolate covering (http://my.clevelandclinic.org/heart/prevention/nutrition/chocolate.aspx). Thus, according to Mark Stibich, PhD from Johns Hopkins School of Public Health, one should avoid dark chocolate that contains nuts, caramel, nougat, and other additives to avoid excess calories and fat (http://longevity.about.com/od/lifelongnutrition/p/chocolate.htm).

          Stibich also offers other valuable insight on dark chocolate detriments. Some studies have shown that it is best to avoid drinking milk while consuming dark chocolate, as it may result in fewer antioxidants from the chocolate being used by one’s body. Chocolate is also a source of fat, and although only one-third of the fat it contains is actually considered “bad” (this one-third is composed of palmitic acid, which is a saturated fat that increases the risk of heart disease and also increases cholesterol), dark chocolate should still be consumed in moderation (http://longevity.about.com/od/lifelongnutrition/p/chocolate.htm).

Conclusion

         

          Based on the previously described websites and scientific studies, it is clear that the question of dark chocolate’s health benefits is not entirely clear-cut. Though it has been proven that the antioxidants in dark chocolate are beneficial to the cardiovascular system and the body in general, dark chocolate is not without its detriments. Dark chocolate still contains fat and is high in calories, and it has been shown to increase the presence of certain fatty acids in the body.

          Given this information, it would be advisable to eat a small amount of dark chocolate occasionally; however, given the disadvantages of the consumption of large portions, it is inadvisable to eat large quantities regularly. Instead, one might try to attain the benefits of dark chocolate in other manners. One should remember that though dark chocolate can arguably help slightly improve cardiovascular function, one does not need to fix something that is not broken, so one should spend more effort eating heart-healthy foods and a balanced diet. In addition, although dark chocolate provides energy and is an anti-depressant, exercise and a proper sleep schedule can offer the body the same benefits in a more natural and healthy way.

          After reviewing the research found on this subject, the best advice is to choose dark chocolate over milk or white chocolate, but to choose other, healthier foods instead of chocolate more often than not. Though studies have shown dark chocolate does offer health benefits, it will always be “better” to eat an apple than a bar of dark chocolate, regardless if it is dark or not.

 

  

 

References

Bayard V., Chamorro F., Motta J., Hollenberg N.K.. (2007). Does flavanol intake influence mortality from nitric oxide-dependent processes? Ischemic heart disease, stroke, diabetes mellitus, and cancer in Panama. Int J Med Sci, 4(1),53–58.

Hermann F., Spieker L.E., Ruschitzka F., Sudano I., Hermann M., Bingelli C., Luscher T.F., Riesen W., Noll G., Corti R..  (2006). Dark chocolate improves endothelial and platelet function. Heart, 92(1), 119-120.

Kelm M. (2002). Flow-mediated dilatation in human circulation: diagnostic and therapeutic aspects. Am J Physiol Heart Circ Physiol, 282, H1–H5.

Mursu J., Voutilainen S., Nurmi T., Rissanen T.H., Virtanen J.K., Kaikkonen J., Nyyssonen K., Salonen J.T.. (2004). Dark chocolate consumption increases HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans, Free Radic Biol Med, 37(9), 1351–1359.

 

 

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