The Risk Factors of Cardiovascular Disease After Consumption of Chocolate

Abstract

The following research essay discusses and critically analyzes the topic of moderate dark chocolate consumption and its effects on the risk factors of cardiovascular disease, namely; hypertension, high cholesterol and insulin resistance. Research of multiple online databases on the topic of choice was conducted and results of these articles have displayed positive outcomes linked to something that society would naturally label as unhealthy-chocolate. It indicated that moderate dark chocolate consumption (50-100 mg per day) has cardioprotective effects on the body. It can significantly lower blood pressure, assist in maintaining healthy cholesterol levels and can help fight insulin resistance.

Introduction/Rationale

To re-iterate what was mentioned above, the chosen topic for investigative exploration is the moderate consumption of dark chocolate and its effects on cardiovascular disease risk factors. Ischemic heart disease and stroke, two cardiovascular diseases, are the first and second leading causes of death in the world (WHO, 2011). Cardiovascular disease has multiple risk factors such as diabetes, obesity, high cholesterol, hypertension and following an unhealthy diet to name a few (World Heart Federation, 2014). Over the years, chocolate, specifically dark chocolate has been associated to a cardioprotective effect in the body by means of controlling the risk factors of cardiovascular disease to normative levels, which could possibly aid in the prevention of cardiovascular disease; a life-threatening, yet very avoidable disease. The research question; “What is the effect of moderate dark chocolate consumption on the risk factors of cardiovascular disease in middle-aged people?” was answered through assessment and review of available evidence-based resources of good quality, reliability and validity on the chosen topic. The paradigm of this topic is positivism. This can be explained through the fact that positivism aims to discover general relations between variables, particularly cause and effect. Furthermore, experiments are designed to measure and explain associations and to test whether a hypothesis can be approved or disapproved (Alderson, 1998).

The biological theory is most befitting to this topic, as it is directly related to the human body and health outcomes of the body, whether it be in structure and/or function. An in-depth look at this theory will be examined further in this research essay in terms of what actually happens to the above mentioned risk factors when dark chocolate is consumed and why, as well as the methodology that was utilized, an account of the current state of knowledge will be given and interpretation/analysis, synthesis and conclusions of the data will be provided.

Methodology

The Research Process

The articles used to understand this topic further as well as answer the key research question involved conducting online, advanced database searches. The databases used were; PubMed, Directory of Open Access Journals, Google Scholar, Monash University Library as well as Ovid Medline. A total number of 33 articles were reviewed out of a total of 2 026 hits. The keywords that were used in these searches included: ‘cardiovascular disease’, ‘cardiovascular health’, ‘dark chocolate’, ‘cardioprotective effects’, ‘risk factors’, insulin resistance’, ‘hypertension’ and ‘cholesterol’. It is useful to note that only English articles, published from 2001 onwards were used. Persons with existing cardiovascular disease of some sort were not included in these studies as the aim was to focus on methods of preventing cardiovascular disease to curb the significantly high figures around the globe in at-risk populations. Data of middle-aged people (45 years old to 65 years old) were observed, however, pregnant women or women on hormone-replacement therapies were discarded from the scope as changes in hormone levels already contribute to fluctuating cholesterol levels which may preserve or be detrimental to cardiovascular function (Francis, 2013).

Study Design

While examining all the primary data found, it can be said that the most suitable study design for addressing the key research question was through a randomized control trial, of which 45% (15 out of 33) of the articles made use of and showed to be effective. It is one of the simplest but most powerful tools of research, and is also known as the gold standard of investigation, especially in establishing casual relationships i.e. chocolate causing a reduction in blood pressure (Stolberg, Norman & Trop, 2004). It would be ideal in the context of this topic as at-risk participants (those who possess any of the three mentioned risk factors) would be allocated randomly to one of two groups, either the control or the intervention; this ensures rigor and fairness within the sampling (Sibbald & Roland, 1998). Baseline data will then be collected before any interventions/controls are administered. Thereafter, a decided dose of dark chocolate is given to the intervention group everyday and the control group receives some type of placebo that resembles chocolate, for about 4-8 weeks and within that time, both groups’ hypertension, cholesterol, and blood sugar/insulin resistance is measured weekly to examine the changes. The study samples also consist of both male and female participants. This is how a classic randomized control trial is usually conducted.

Current State of Knowledge

Although several studies have been conducted, especially in the last 15 years or so, of this specific topic, it seems that the results of these studies have not widely been received or acknowledged by the common folk. In the field of health research however, there seems to be a growing interest in the area of chocolate having health benefits. To date, after reviewing many journal articles, there are a few key points that we should understand and can be put down as what we know thus far regarding these benefits, such as:

1. The beneficial ingredient in the chocolate is called Flavonoids and is found within the cocoa of the chocolate. The specific flavonoid is known as Flavan-3-ol (Steinberg, Bearden & Keen, 2003). Many sources of food appear to possess these flavonoids such as tea, fruit, vegetables and red wine (Afoakwa, 2008), but it can be said that cocoa, and therefore dark chocolate exhibits the highest flavonoid capacity compared to the other foods (Shrime, Bauer, McDonald & Coltart, 2011). Flavonoids are a natural occurring polyphenolic dietary antioxidant that can effectively remove potentially damaging oxidizing agents in the body as well as have natural anti-inflammatory characteristics (Mathur, Deveraj & Grundy, 2002). The reason why this essay talks about dark chocolate rather than milk chocolate is because the darker the chocolate, the higher the cocoa volume (Cacao Percentages, 2014).
2. The term “moderate” in dark chocolate consumption. It was observed that the term moderate dark chocolate consumption differed across the several studies. It is essential to understand what is meant by the term moderate, so that the benefits of this intervention can be enjoyed by many. Too little dark chocolate a day can be ineffective at controlling cardiovascular risk factor levels, although too much dark chocolate may still reduce some risk factors like blood pressure and high cholesterol but still has the ability to bring about other cardiovascular disease risk factors such as obesity, which again, opens the doors for additional harmful risk factors. According to randomized control trials conducted by Destch, Eitel & Schuler (2010) and Latham, Hensen & Minor (2013), the correct amount of dark chocolate a person should be having a day is 25-50 grams. Faridi, Dutta & Katz (2008) and Allen, Evans & Erdman (2007) however, states that a good amount of dark chocolate a day would be exactly 22 grams but Abdullah Al-Faris (2008) administered up to 100 grams in her study. After close review of 33 articles, it was found that the approximate average of the daily consumption of dark chocolate should be around 50-100 grams.
3. The bioavailability of dark chocolate on an individual. “Bioavailability refers to the maximum amount of a substance that is absorbed into the body, and how quickly that maximum amount becomes available to the body” (Weber, 2008). Chocolate flavonoids have depicted a good dose response bioavailability in humans (Ding, Hutfless & Girotra, 2006). This simply means that most of what is ingested is absorbed and used by the body in a very quick manner, leaving very little leftover to be free and excreted. A persons bioavailability to a substance or drug may differ from one to another because it is also dependent on factors such as age, weight and height, metabolic rate and gender to name a few (Le, 2014). It is essential to note the bioavailability of a substance on the body, in this case chocolate, because although the intervention group may all be receiving the same dose of dark chocolate a day, their reactions and biological outcomes of it may differ because they are not all the same with regard to the factors mentioned above. Bioavailability is a crucial tool in pharmaceuticals, if future studies prove the health benefits of chocolate then it may even stimulate the opportunity for development of medicinal chocolate, in which bioavailability will be used to calculate the required dosage (Stone, 2014).

Analysis and Synthesis of the Data

This paper spoke in detail about the dark chocolate and the health benefits the flavonoids in it display, but now it will discuss exactly what those benefits are in context with the literature and the three specific cardiovascular risk factors it is targeted at; hypertension, insulin resistance and high cholesterol.

Hypertension

Hypertension is increased blood pressure, which simply means the pressure of the blood in the body’s blood vessels is higher than what is should be, putting extra strain on the body’s cardiovascular system. According to the Center for Disease Control and Prevention (2014), sixty seven million U.S adults (1 in 3 people) have hypertension and as much as 53% of those affected, do not have their condition under control. These are shocking figures as hypertension is the biggest risk factor to cardiovascular disease, and is highly modifiable and dependent on he individual’s actions and behaviors (World Heart Federation, 2014).

Results:

According to Allen et al., (2008), moderate dark chocolate consumption significantly reduced blood pressure in a 4-8 week randomized control trial of 650 participants. The consumption of small dark chocolate bars reduced both systolic and diastolic blood pressure by about 8,2%, although this change seemed to only be evident from the fourth week of administering it. It is also useful to note that in this study, over the given period of time, the body weight of the subjects did not change from the baseline data collected. This is a great advantage as it shows the benefits of moderate dark chocolate consumption without it adding any harmful factors to the body if done correctly. Another randomized control trial conducted by Almoosawi, Fyfe & Clement (2009), also depicted a significant reduction in blood pressure from baseline to around week 5 of the intervention. This study linked the reduction in blood pressure directly to enhanced vascular function from ingesting the chocolate.

Discussion:

The relationship between blood pressure and CVD is continuous and the smallest reductions in blood pressure can substantially decrease CVD around the globe. Latham et al., (2014), talks about the link between these variables involving a substance known as endothelial nitric oxide (NO). It goes on to say that the intake of cocoa flavonoids increases the NO generation, which in turn prevents leukocyte adhesion, platelet adhesion and smooth muscle cell proliferation leading to vasodilation and lastly a beneficial reduction in blood pressure.

Insulin Resistance

According to the National Diabetes Information Clearinghouse (2014), “insulin resistance is a condition in which the body produces insulin but does not use it effectively.” Instead of being absorbed up by the cells, glucose in the body builds up in the blood, and as a result may lead to diabetes, which is also a great risk factor of cardiovascular disease and can be life-threatening.

Results:

Grassi, Desideri & Ferri (2013) conducted a study to measure the effects of flavonoid rich chocolate on hypertension and insulin resistance. Results suggest that when the participants were given flavonoid rich chocolate, their insulin resistance decreased by 0.31%. Although this is small reduction, it was observed that those who received a placebo containing no flavonoids showed no decrease in insulin resistance at all. The study also showed that insulin sensitivity had increased over a short-term period of dark chocolate consumption and was measured using an insulin sensitivity index. This resulted in the insulin responses to glucose in the body being significantly improved, ultimately reducing the blood glucose levels up to 1.6%. Shrime et al., (2011), also displays results that 100mg of flavonoid rich chocolate a day can reduce insulin resistance by 0.94%.

Discussion:

According to Latham et al., (2014), the impairment of insulin-stimulated NO production contributes to the body’s metabolic insulin resistance and therefore, by enhancing the NO bioavailability by consumption of dark chocolate, insulin resistance will decrease and insulin sensitivity increase. This makes it much easier for the body to break down and metabolize the glucose in the body and significantly reduces cardiovascular risk. Majority of the studies measuring these variables made use of a specific tool of measurement; the homeo- stasis model assessment of insulin resistance (HOMA-IR). This tool estimates steady state beta cell function (%B) and insulin sensitivity (%S), as percentages of a normal reference population (University of Oxford, 2014).

High Cholesterol

Cholesterol is a waxy substance that is found within the lipids (fats) of the body, although the body requires this to build healthy cells, high cholesterol can result in a build up of fatty deposits in and around the blood vessels, which significantly increases the probability of suffering from heart disease (Mayo Clinic, 2014). RESULTS: Fraga, Keen & Goretta (2005), investigated the regular consumption of flavonoid rich diets on cardiovascular disease risk and reports results that 105 grams of dark chocolate daily has proved to decrease plasma cholesterol up to 11%, and LDL cholesterol up to as much as 15%. Ding et al., (2006) found that as little as 31 grams of dark chocolate a day can increase HDL cholesterol. This is highly beneficial as LDL cholesterol is what is known as the ‘bad’ cholesterol as it leads to plaque build-up and atherosclerosis, while HDL cholesterol is the ‘good’ cholesterol and helps remove the LDL cholesterol (American Heart Association, 2014). By reducing LDL cholesterol and increasing HDL cholesterol significantly reduces the risk of cardiovascular disease.

Discussion:

Flavonoid rich substances like dark chocolate lower LDL cholesterol by inhibiting cholesterol absorption in the digestive tract and inhibiting LDL cholesterol production (Latham et al., 2014). If there is too much LDL cholesterol in the body, the cardiovascular system works extra hard to pump the blood around as atherosclerosis has reduced the size of the blood vessels. This increases the blood pressure drastically, putting a person at high risk of CDD and it is therefore very beneficial to keep LDL cholesterol at a low.

Gaps Within the Literature

During the research, a number of gaps in knowledge were identified. In order to understand and explore the topic of moderate dark chocolate consumption and its cardioprotective effect more, it is of utmost importance to address these gaps in the near future. Some of the pitfalls include:

• The high probability of confounding variables. Due to the nature of this topic, measuring cardiovascular risk, there will always be other factors contributing to the positive or negative outcomes in the body such as age, sex, weight and height as well as hereditary characteristics. This makes it a little more difficult to find an accurate causal relationship as results may be altered in one or more ways depending on the factors mentioned above.
• Although some of the study samples were quite large, majority of them were not. Some studies even used as little as 10-20 participants. Small sample sizes make it difficult to generalize the findings to the population.
• Even though several studies have been conducted over the past decade and more on this topic, it is still difficult to state the exact amount of dark chocolate needed to enjoy the maximum benefits of it as the articles all differ from one another. All dark chocolate isn’t the same as well, making it even harder to give a proper estimate.
• Although the average person may read articles in things like magazines or newspapers on this topic, scientific, evidence-based data and articles are not easily accessible to them as they could benefit greatly from knowing the facts about the topic and by putting it into practice.

Addressing the Gaps

A suggested checklist to improve the above-mentioned gaps in future research includes:

• Conducting randomized control trials where possible as it is one of the most scientifically sound ways of investigation.
• Attempt to publish all literature whether it is positive or null discoveries so that the wider public can learn more on the topic.
• Use well-defined cocoa and chocolate, and if possible for industry to allow similar cocoa/chocolate to be available for independent researchers for future studies/repeating work.
• Ensure bioavailability of the dark chocolate within its environment.
• Use an appropriate control for non-flavonoid chocolate.
• Use a daily dose of chocolate that can readily be implemented into the diet.
• Use much larger sample size to explore the relationship between the variables.
• Ensure participants within the sample are similar as possible to one another so that other factors contribute less to the outcome.

Conclusion

Cardiovascular diseases, the category that accounts for the most deaths in the world, can be prevented and managed in many differed ways, as most of its risk factors are highly modifiable. Dark chocolate consumption in moderation has been linked to cardioprotective effects in the body with relation to many CVD risk factors, over and above the ones mentioned in this paper. In conclusion, moderate dark chocolate consumption does lower blood pressure, fight insulin resistance and reduce LDL cholesterol, putting an individual at a lowered risk of developing CVD. Future studies need to be conducted to explore this topic further as it can be regarded as fairly new in the health research industry.