Revealing the “Dark” Side of ChocolateNovember 14th, 2014
By: Ruth Choi, PharmD Student
For centuries, cocoa has been consumed for its pleasurable taste as well as for its health benefits. Today, research attempts to explain how cocoa may be beneficial to our overall health, specifically cardiovascular health. Chocolate- Guilty Pleasure or Healthy Supplement is a review paper that was recently published in The Journal of Clinical Hypertension. In the paper, Latham et al discuss major studies done with cocoa to determine how cocoa acts in the body to produce cardiovascular benefits and whether it can be consumed as a dietary supplement.
The unique diet and health of the Kuna Indians initially sparked research on dark chocolate consumption and cardiovascular health. From the San Blas Islands of Panama, Kuna Indians consume about four 8-ounce cups of unprocessed cocoa drinks per day and have exceptionally low rates of hypertension and cardiovascular disease (CVD) even to old age.1 For instance, the mean blood pressure (BP) was 110/70 mm Hg in the elderly over 65 years.1 Cocoa comes from the Theobroma cacao tree, and a major component of it is flavanol. One of the proposed mechanisms is flavanols are responsible for improving blood flow by stimulating the endothelium of blood vessels to produce more nitric oxide (NO) and increase vasodilation.1 Improving blood flow subsequently reduces CVD risk factors such as hypertension, platelet dysfunction, insulin resistance, and hypercholesterolemia.1. Heiss et al researched the effects of cocoa intake in smokers and found that drinking cocoa high in flavanols (176-185 mg) increased NO levels and reversed endothelial dysfunction.2 One way the body naturally produces NO is through insulin stimulation. Insulin resistance occurs in individuals who do not respond to insulin’s action on blood vessels to produce NO. In a study done by Grassi et al, flavanol-rich dark chocolate proved to decrease BP and insulin resistance and improved blood flow in hypertensive patients.3
Cholesterol also plays a significant role in cardiovascular health. Dark chocolate is thought to increase HDL-C levels, which is the good cholesterol. In a 3-week study done on healthy subjects, Mursu et al found that consuming either 75 g of dark chocolate or flavanol-rich dark chocolate daily increased HDL-C levels by 11.4% and 13.7%, respectively.4 On the contrary, some studies will argue that it is actually theobromines in cocoa that help increase HDL-C levels.1 Further research is needed to determine whether flavanols or theobromines increase HDL-C levels.
Many recent studies show the benefits of cocoa intake on cardiovascular health. Due to its delectable taste, relative safety, and low cost, cocoa-rich dark chocolate is being considered as a health supplement. Major hindrances to its use, however, are the caloric intake and limitations of many of the studies.1 Due to its high caloric, saturated fat, and sugar content, chocolate needs to be consumed with caution, especially in obese patients. Though less palatable, people could consume cocoa-based products with less sugar or saturated fat. Latham et al explain the limitations that are apparent in all of the studies that were reviewed.1 One of the major limitations is the variability in flavanol content in all the studies making it difficult to interpret and compare the results. It also hinders making effective dosage recommendations for patients. Another limitation is the small sample sizes in all the studies making it difficult to generalize the results to a larger, more diverse population. The short duration of the studies is another limitation because it is unknown whether cocoa intake would produce these same results if given long term. Therefore, further research is needed until we can recommend dark chocolate as a health supplement. Nonetheless, one thing you can take away from the research is that you don’t have to feel guilty anymore about eating ‘healthy’ dark chocolate in moderation as part of your dietary lifestyle changes to prevent and treat CVD risk factors.
The Dietary Approaches to Stop Hypertension (DASH) diet recommended by the National Heart, Lung, and Blood institute (NHLBI) consists of eating a diet rich in fruits, vegetables, and low-fat dairy products to improve BP.5 Many supplements also exist that have been significantly proven to have antihypertensive effects. What sounds better, chocolate or veggies?
- Latham L, Hensen Z, Minor D. Chocolate—Guilty pleasure or healthy supplement? JCH. 2014;16(2): 101. http://onlinelibrary.wiley.com/doi/10.1111/jch.12223/full. Published February 2014. Accessed October 29, 2014.
- Heiss C, Dejam A, Kleinbongard P, Schewe T, Sies H, Kelm M. Vascular effects of cocoa rich in flavan-3-ols. JAMA. 2003;290(8): 1030. http://jama.jamanetwork.com/article.aspx ?arti cleid=197170. Published August 27, 2003. Accessed October 29, 2014.
- Grassi D, Necozione S, Lippi C, et al. Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. HYP. 2005:46(2): 398. http://hyper.ah ajournals.org/content/46/2/398.full.pdf+html. Published July 18, 2005. Accessed October 29, 2014.
- Mursu J, Voutilainen S, Nurmi T, et al. Dark chocolate consumption increases HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans. FRBM. 2004:37(9): 1351. http://www.sciencedirect.com/science/ article/pii/S0891584904004551. Published November 1, 2004. Accessed October 29, 2014.
- What Is the DASH Eating Plan? National Heart, Lung, and Blood Institute. Available from: http://www.nhlbi.nih.gov/health/health-topics/topics/dash/