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As a chocolate lover, I am glad that chocolate seems to have many health related benefits. Along with other benefits, studies have shown a correlation between chocolate consumption and having a lower risk for developing cardiovascular disease. According to Frank Ruschitzka, spokesman for European Society of Cardiology, “dark chocolate improves vascular and platelet function” (CBS News). Chocolate is also believed to lower blood pressure. Through all the information I researched, there seems to be a general understanding that chocolate consumption really does have an inverse relationship with heart disease. Yet, disagreement remains regarding: how much chocolate is necessary to consume, whether the type of chocolate matters, and whether this correlation is linked to blood pressure. I found information on five different studies that all show this relationship between chocolate and heart disease, and I looked at two of the studies more in depth.

All of these five studies indicate the importance of the flavonoids in cocoa within the chocolate. Flavonoids are a type of polyphenol, which is found in other foods like red wine, fruit, and nuts (NCBI).  The flavanols (a type of flavonoid) in chocolate are believed to widen blood vessels which in turn lower blood pressure (CBS News).  Flavonoids act as antioxidants by, “protecting the body from free radicals, which can cause damage that leads to heart disease” (Dr. Mittleman BIDMC). It is also believed that flavanols improve endothelial function (Zutphen Study). Flavanols also prevent white blood cells from sticking to blood vessel walls. This could lead to arthrosclerosis (Science Daily), which is the build up of plaque in arteries (NHLBI). Darker chocolate contains a higher flavanol content; white chocolate does not contain flavanols. (BIDMC).  The constant between these five studies is that flavonoids are the chemical component of chocolate that gives it these benefits.

The first study I analyzed, The Zutphen Study, measured cocoa intake through chocolate consumption and how it affects blood pressure and cardiovascular mortality. Beginning in 1985, this study was performed on 470 elderly men who did not have any cardiac problems initially. The subjects were interviewed about their daily chocolate intake. The highest tertile averaged around eating 4.18 grams of cocoa per day, while the lowest ate almost no chocolate. For reference, 100 grams of dark chocolate contains 43 grams of cocoa on average (Table 1, Zutphen Study). The study found that men who ate more cocoa also ate more nuts, alcohol, and more calories in general; these men also ate less meat and coffee. The researchers also found no link between BMI and physical activity with chocolate intake. The results found that cocoa consumption was inversely related to blood pressure and cardiovascular mortality. Upon follow-up, this study found that for those in the lowest tertile, 36% of participants died from cardiovascular related problems while only 27.2% in the highest tertile died due to cardiovascular disease. In terms of blood pressure, the researchers actually did not think that lower blood pressure due to chocolate consumption lowered the risk of cardiovascular mortality. They believed the lower risk of cardiovascular mortality was due to reasons independent of blood pressure. While the results of this survey seem promising, it seems as if the sample was too small and specific to be applied to a greater population.

The next study I looked at, The National Heart, Lung, and Blood Institute Family Heart Study, was published more recently in 2011 and analyzed a larger and more diverse sample of participants – 4,970 subjects ranging from 25-93 years old. This study found that chocolate consumption had an inverse relationship with prevalent coronary heart disease (CHD). These results could be applied more appropriately to the general population of Americans. Yet, the data was collected through annual questionnaires, which could prove skeptical. The questions related to chocolate asked the participants to choose the amount of chocolate they ate daily or weekly over the past year from eight different options. This could have been difficult for subjects to remember or generalize into an appropriate average. This study found that participants who ate chocolate more than five times per week were associated with a 57% lower prevalence of CHD than subjects who ate no chocolate, once adjusted for variables including smoking, alcohol intake, exercise, education, non-chocolate candy consumption, age, sex, fruit and vegetable intake, and dietary acid (NCBI). This relationship was not affected by gender or race, meaning it could be applied to many different types of people. Yet, this study found that higher chocolate consumption was linked to younger age, higher BMI (unlike the previous study), and lower consumption of fruits and vegetables. It also found that increasing non-chocolate candy consumption increased the risk for CHD. Also, surprisingly, this study found that once adjusting for age and sex, the inverse relationship between chocolate consumption and blood pressure did not remain. Besides the questionnaires, another limit to this study was that it did not differentiate between dark and milk chocolate so it does not give us information on whether one type is more beneficial. This study also does not specify how much chocolate per day should be eaten, only the optimal weekly amount.

While these two studies show positive results, would the correlation remain the same for different types of participants? A German study observed the habitual chocolate consumption for around 20,000 adults for over eight years. This study found that people who ate an average of six grams of chocolate per day, which is the equivalent of one square of a chocolate bar, had a 39% lower risk for heart attack or stroke (DIFE). Compared the Zutphen study, this study still gives promising results even though the participants were consuming less chocolate than those in the highest tertile of the Zutphen Study. Another study was performed in Sweden on patients who recently suffered a heart attack. These participants were followed for eight years following their heart attacks. Those who ate chocolate at least once a week reduced their risk of cardiac death by 44% (BIDMC). This study is important because it shows how chocolate potentially has the ability to reverse symptoms of cardiac disease. A third study, performed in the Netherlands, tested to determine if increasing flavanol content within chocolate had more positives results than regularly produced chocolate. This study tested 44 overweight men for two months. The participants were asked to eat 70 grams of chocolate per day (around 1.5 average sized chocolate bars). The subjects were either given flavanol enriched chocolate or regularly produced chocolate (Science Daily). Surprisingly, artificially increasing flavanol content past the level in dark chocolate did not have any further health benefits. This inverse relationship between chocolate and heart disease remains even when greatly increasing sample size or for people who have already experienced previous cardiac problems, even in the long term. Surprisingly, altering flavanol content does not lower the risk even further. This could mean that the distinction between milk and dark chocolate is not as important as commonly thought.

These five studies all confirm chocolate’s positive health benefits. Not only does chocolate taste delicious, but also it lowers one’s risk for heart disease. While chocolate could seem like the perfect “medicine” to cure America’s number one cause of death (CDC), it is important to keep in mind that chocolate also contains a large amount of calories for the amount of food and nutrients actually being consumed. In 100 grams of chocolate, with around 30-43 grams of cocoa (Table 1 Zutphen Study), there is about 500 calories (CBS News). So, two bars of chocolate contain about 25% of the recommended daily caloric intake. Each study recommends a different optimal level of chocolate consumption per day or per week, yet it is also important to eat chocolate in moderation due to its high amount of calories.

There seems to be a solid consensus that chocolate is directly linked to a lower risk of developing cardiovascular disease. These five studies disagree on the optimal amount of chocolate necessary, whether the affect of lower blood pressure is the reason behind this relationship, and whether the distinction between dark and milk chocolate matters in terms of health. The family heart study is important because it finds that race and sex do not alter whether this relationship holds. The risk percentage results of the German study seem most promising because it used the largest sample size over a long period of time. The heart attack study is important because it tells us that chocolate possibly has the ability to reverse damage already done to the heart. The flavanol study in the Netherlands adds an interesting twist, reporting that chocolate type may not be as substantial as it is usually thought to be. So no need to feel guilty about eating a little chocolate each day; its good for your heart!

Works Cited:

Zutphen Study: http://archinte.jamanetwork.com.proxy.lib.umich.edu/article.aspx?articleid=409867

http://www-ncbi-nlm-nih-gov.proxy.lib.umich.edu/pubmed/16505260

Buijsse B, Feskens EM, Kok FJ, Kromhout D. Cocoa Intake, Blood Pressure, and Cardiovascular Mortality: The Zutphen Elderly Study. Arch Intern Med. 2006;166(4):411-417. doi:10.1001/archinte.166.4.411.

CBS News: http://www.cbsnews.com/news/study-chocolate-could-reduce-heart-risk/

NCBI/ The National Heart, Lung, and Blood institute family heart study:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039704/

BIDMC: http://www.bidmc.org/YourHealth/Health-Notes/Keeping-Your-Heart-Healthy/Living-a-Heart-Healthy-Lifestyle/The-Truth-About-Chocolate-and-Your-Heart.aspx

Science Daily: http://www.sciencedaily.com/releases/2014/02/140227092149.htm

Federation of American Societies for Experimental Biology. “Why dark chocolate is good for your heart.” ScienceDaily. ScienceDaily, 27 February 2014. <www.sciencedaily.com/releases/2014/02/140227092149.htm>.

CDC:http://www.cdc.gov/nchs/fastats/lcod.htm

DIFE:http://www.dife.de/en/index.php

NHLBI: https://www.nhlbi.nih.gov/health/health-topics/topics/atherosclerosis/)

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