Abstract

1. Evidence is Insufficient to Support A Role for Chocolate or Cocoa in Increasing High Density Lipoprotein Cholesterol (HDL-C) in Healthy Normal Weight or Overweight Adults El-Zibdeh NM, RD, Rittenhouse MA, PhD, RD, CSSD, Brevard, PB, PhD, RD, FADA, Domangue RJ, PhD James Madison University, Harrisonburg, VA Abstract High density lipoprotein cholesterol (HDL-C) is a risk factor for coronary heart disease (CHD). There is an indication that cocoa and chocolate products increase HDL-C level. The purpose of this evidence analysis is to evaluate whether there is strong evidence to support this relationship in healthy normal-weight and overweight adults. Eleven randomized controlled trails (RCT) were identified in which cocoa, chocolate, or a combination were an intervention and reported HDL-C level as a dependent factor. Each study was reviewed by four reviewers using the Evidence Analysis Manual adopted by the Evidence Analysis Library of the American Dietetic Association. This evidence analysis was assigned Grade II, indicating that there is fair evidence that daily chocolate and cocoa consumption does not increase HDL-C in healthy normal-weight and overweight adults.  Only four (three neutral and one negative quality) studies observed a significant increase in HDL-C compared to controls. Cocoa and chocolate may elicit this effect by increasing the level of Apolipoprotein A1 (ApoA1) production. Lack of positive results in the remaining studies might be explained by selection bias, normal baseline HDL-C level, or small sample sizes. Nevertheless, cocoa and chocolate may have other cardiovascular benefits, or at least have a neutral effect on lipids, and can be incorporated in the diet without weight gain. Future research that focuses on HDL-C level in relation to other lipids and in people with low HDL-C might lead to different conclusions. Results Eleven articles met the inclusion criteria. The results are summarized in Figure 2 and Table 1. This study was assigned Grade II, indicating that there was fair evidence that chocolate does not increase HDL-C compared with controls, since there were conflicting results and some studies were of strong design whereas others had weaknesses. Discussion There is insufficient evidence that daily chocolate and cocoa consumption increases HDL-C in healthy normal-weight and overweight adults (grade II).Only four of the eleven studies found statistically significant changes in HDL-C (10-13). Kris-Etherton (10) substituted a carbohydrate snack with milk chocolate or another carbohydrate snack, which agrees with evidence that substituting carbohydrates with fats improves HDL-C levels (3). While Joo (11) found that milk chocolate significantly increased HDL-C, the study received negative rating because the amount of chocolate, statistical analysis, and recruitment methods were unclear. Baba (12) found that a cocoa drink increases HDL-C significantly compared to a sugar drink.This neutral study also lacked information on participant selection, statistics, and specifics of the intervention. Wan (13) found HDL-C to be greater by 4% compared to the control group. However, baseline HDL-C was reported for all participants and not for each group separately, thus baseline levels may not have been similar. Chocolate is gaining a healthy food reputation. Stearic acid, a SFA and the main fatty acid in chocolate, has a neutral effect on total cholesterol and LDL-C (2, 17), possibly because it converts to oleic acid in the body. Other SFAs, such as lauric, myristic, and palmitic, raise HDL-C and LDL-C concurrently. Furthermore, cocoa and chocolate contain more flavonoids (potent antioxidants) than black tea, red wine, cranberry juice, or apples (18). Cocoa may raise HDL-C level by increasing ApoA1 production, the main protein in HDL-C particles. In one in vitro study, human hepatic HepG2 and intestinal Caco2 cells were incubated with cocoa polyphenols. After 24 hours, ApoA1 level increased (19). This hypothesis may be supported by another study that found increased expression and production of ApoA1 in a human hepatic HepG2 cells by genistein, a flavonoid in soy beans and coffee (12). There are several potential explanations for the lack of association between cocoa or chocolate and HDL-C in the remaining studies (6-9, 14-16).Recruitment, inclusion/exclusion, and demographic information were not reported adequately, raising the possibility of selection bias. Baseline HDL-C was <40 mg/dL in one study (9), and normal (6-8, 10, 12-16) or unreported (11) in the remaining. It may not be possible to increase HDL-C beyond the normal range.Sample sizes were small, and power was not calculated to determine the number needed to observe a significant change in HDL-C, since it was not the main outcome in some studies. Cocoa and chocolate may have other cardiovascular benefits. Their consumption improved endothelial function (7, 15, 16), increased coronary flow velocity reserve (6), reduced LDL-C oxidation (12, 13), reduced stress markers (12), and lowered serum triglycerides (8, 10). Total cholesterol and LDL-C were either lowered (9, 12) or remained unchanged (6-8, 10, 14-16). All eleven studies reported no weight gain. 3 dark chocolate (6-8) 33 Studies Identified 2 milk chocolate (9, 10) 9 Not RCT 1 milk or dark chocolate as two different treatments (11) 9 RCTs in Normal Weight 24 RCTs 4 diabetic 4 hypercholesterolemic 4 hypertensive 1 people with CAD 1 cocoa powder (12) 2 dark chocolate and cocoa powder as one treatment (13, 14) 11 RCTs Healthy Adults 2 RCTs in Overweight 2 cocoa powder (15, 16) Figure 2. Article inclusion and exclusion. Articles grouped based on the type of cocoa or chocolate used for the intervention. The numbers in parenthesis reflect the reference number. Introduction Coronary heart disease is the most common type of cardiovascular disease, which affects more than 16 million American adults (1). In 2007, one out of six deaths in the United States was attributed to CHD, and in a given year, 34% of those who experience a coronary attack will die from it (1). There is an inverse relation between HDL-Clevel and the risk of a CHD event.Alow HDL-C level—less than 40 mg/dL in men and women—is a strong independent predictor of CHD(2). A 1-mg/dL increase in HDL-C significantly lowers the risk for CHD by 2% in men and 3% in women (3). It is well established that the diet affects HDL-C level(4). Very high intake of carbohydrates (> 60% of calories) and consumption of trans fatty acids lower HDL-C, while diets high in unsaturated fatty acids and soy protein raise it (2). Saturated fatty acids (SFA) may or may not affect HDL-C level (2). The effect of chocolate on HDL-C level is inconclusive. There’s an indication that cocoa and chocolate may raise HDL-C; however, a recent meta-analysis found otherwise (5). Therefore, the purpose of thisanalysis isto examine the strength of the evidence that chocolate and cocoa consumption increases HDL-C in healthy normal-weight and overweight adults. Conclusion The current body of evidence is insufficient to support cocoa or chocolate’s role in increasing HDL-C level in healthy normal weight or overweight adults. Future research should focus on HDL-C as the main outcome and how it is related to other lipids and lipoproteins. In addition, research should focus on individuals with low HDL-C levels to determine if HDL-C increases with chocolate or cocoa consumption in this group. Methods Electronic and manual searches were conducted between August 1, 2011 and September 9, 2011 using eight search combinations in two databases (Figure 1). Inclusion criteria were limited to RCT; healthy human adults of normal weight or overweight; cocoa, or chocolate, or a combination as the independent factor; and HDL-C level as a dependent factor. Exclusion criteria were studies written in languages other than English;interventions that used fortifiedproducts or extracts; or participants with hypertension, diabetes, dyslipidemia, or other chronic conditions. No restriction was made on publication date. References Roger VL, Go AS, Lloyd-Jones DM, Adams RJ, Berry JD, Brown TM, et al. Heart Disease and Stroke Statistics 2011 Update: A Report from the American Heart Association. Circulation. 2011;123:e18-e209. Expert panel on detection, evaluation, and treatment of high blood cholesterol in adults. Executive summary of the third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). JAMA. 2001;285:2486-2497. 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The analysis followed methods adopted by the Evidence Analysis Library of the American Dietetic Association detailed in the Evidence Analysis Manual, 2010. Four reviewers independently reviewed each study then came to consensus on its rating.