Cocoa products, which are rich sources of flavonoids, have been shown to reduce blood pressure and the risk of cardiovascular disease. Dark chocolate contains saturated fat and is a source of dietary calories; consequently, it is important to determine whether consumption of dark chocolate adversely affects the blood lipid profile. The objective was to examine the effects of dark chocolate/cocoa product consumption on the lipid profile using published trials. A detailed literature search was conducted via MEDLINE (from 1966 to May 2010), CENTRAL and ClinicalTrials.gov for randomized controlled clinical trials assessing the effects of flavanol-rich cocoa products or dark chocolate on lipid profile. The primary effect measure was the difference in means of the final measurements between the intervention and control groups. In all, 10 clinical trials consisting of 320 participants were included in the analysis. Treatment duration ranged from 2 to 12 weeks. Intervention with dark chocolate/cocoa products significantly reduced serum low-density lipoprotein (LDL) and total cholesterol (TC) levels (differences in means (95% CI) were −5.90 mg/dl (−10.47, −1.32 mg/dl) and −6.23 mg/dl (−11.60, −0.85 mg/dl), respectively). No statistically significant effects were observed for high-density lipoprotein (HDL) (difference in means (95% CI): −0.76 mg/dl (−3.02 to 1.51 mg/dl)) and triglyceride (TG) (−5.06 mg/dl (−13.45 to 3.32 mg/dl)). These data are consistent with beneficial effects of dark chocolate/cocoa products on total and LDL cholesterol and no major effects on HDL and TG in short-term intervention trials.
Chocolate and cocoa are produced from cacao beans, the seed of Theobroma cacao, and are known to contain fats (the dry weight of whole cacao beans is composed of 50–57% lipid, often called cocoa butter (Hannum and Erdman, 2000)). This cocoa butter, predominantly found in dark chocolate, is composed on average of 33% oleic acid, 25% palmitic acid, and 33% of stearic acid. (http://www.nal.usda.gov/fnic/foodcomp/search/), the latter two being saturated fats. Cocoa products are also very rich in plant phytochemicals, especially flavonoids, which are now objects of increased scientific attention due to their potential health benefits (Engler et al., 2004; Grassi et al., 2005a; Wang-Polagruto et al., 2006; Almoosawi et al., 2010).
Previous studies have suggested that dark chocolate consumption reduces blood pressure (Grassi et al., 2005b; Grassi et al., 2008), improves insulin sensitivity as shown by significantly higher QUICKI (quantitative insulin sensitivity check index) measurements (Grassi et al., 2008), improves vascular endothelial function and reverses vascular dysfunction (Engler et al., 2004; Grassi et al., 2005b; Wang-Polagruto et al., 2006), reduces insulin resistance as evidenced by significantly lower HOMA-IR (homeostasis model assessment of insulin resistance) (Grassi et al., 2005a) measurements, and increases serum total antioxidant capacity (Wan et al., 2001).
Despite solid evidence on the beneficial effects of dark chocolate on blood pressure, limited data exist on the effects of dark chocolate on blood lipids. One clinical trial indicated that regular ingestion of dark chocolate may have no adverse effects on serum lipid profile (Crews et al., 2008), whereas others have suggested that intake of dark chocolate reduced serum LDL cholesterol and triglyceride (TG) levels (Engler et al., 2004; Grassi et al., 2005b), and increased serum high-density lipoprotein (HDL) cholesterol measurements (Mursu et al., 2004). An earlier meta-analysis of eight randomized trials involving 215 subjects reported that an intervention with dark chocolate was associated with a significant reduction in serum LDL in subjects with cardiovascular disease risk factors (Jia et al., 2010) compared with placebo. However, that meta-analysis did not assess the effect of dark chocolate or cocoa on serum TG concentrations and it did not include some important recent studies.
Dark chocolate is a food consumed frequently and widely all over the world. It is therefore relevant to understand its net benefits on health in order to help the public make informed choices. Hence, we sought to review current evidence on the effects of dark chocolate/cocoa products consumption on serum LDL, HDL and TGs using completed randomized trials.
Authors & Affiliations
Division of Aging, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USAO A Tokede, J M Gaziano & L Djoussé
Harvard Medical School, Boston, MA, USAJ M Gaziano & L Djoussé
Massachusetts Veterans Epidemiology and Research Information Center and Geriatric Research, Education, and Clinical Center, Boston Veterans Affairs Healthcare System, Boston, MA, USAJ M Gaziano & L Djoussé