The oxidation of LDL cholesterol has a role in the development of coronary artery disease: atherosclerosis. Uptake of oxidized LDL by macrophages and smooth muscle cells leads to the formation of fatty streaks, a key stage in early atherosclerosis. These vascular lesions accumulate large amounts of lipids(fats) such as cholesterol ester.
In addition, oxidized LDL induces the expression of adhesion molecules in monocytes, such as vascular cell adhesion molecule-1 and intercellular adhesion molecule-1, and also increases production of growth factors by smooth muscle cells and fibroblasts. These cellular components compile and create an inflammatory nest (cellular blockage) within the artery. As such, inhibition of LDL oxidation is thought to suppress atherosclerotic lesions.
Cocoa powder is rich in polyphenols such as catechins and procyanidins and has been shown to inhibit LDL oxidation and atherogenesis. Studies indicate the intake of cocoa powder lessens the susceptibility of LDL to oxidation. This protective mechanism of cocoa consumption is brought about by an increase in HDL cholesterol concentrations. High HDL concentrations inhibit oxidation of LDL cholesterol.
The results of a current study indicate that consumption of cocoa powder containing 26 g/day of polyphenolic substances for twelve weeks increased the resistance of LDL to oxidation and increased HDL cholesterol concentrations in individuals with normal cholesterol and mildly high cholesterol.
In this study, a significantly greater increase in plasma HDL cholesterol (24%) was observed in the cocoa group than in the control group (5%).
The results of this study are consistent with other studies that show a positive correlation between inhibition of LDL oxidation and the phenolic compounds derived from (red) wine or the concentration of major polyphenols in cocoa powder such as catechin, epicatechin, and their oligomers.
The second study noted below reported that HDL-cholesterol concentrations increased by 11% and 14% after 3 week intake of dark chocolate or dark chocolate enriched with cocoa polyphenols. The daily consumption of catechin and procyanidins in this study was 270 mg with the dark chocolate and 420 mg with the polyphenol-enriched dark chocolate.
The results of this study indicate that the increase in plasma HDL-cholesterol concentrations caused by polyphenols may be dose-related. This study also hypothesize that chocolate fatty acids may modify the fatty acid composition of LDL and make it more resistant to oxidative damage.
According to Richard Karas, M.D., Ph.D., in a presentation at the American Heart Association Scientific Sessions 2004, changes in high density lipoprotein-cholesterol (HDL-C) and HDL-C-inclusive parameters are the strongest predictors of coronary heart disease risk reduction in lipid intervention trials.
Cacao beans are used as an ingredient in cocoa and chocolate. Cacao beans are rich in polyphenols, such as catechin, epicatechin, procyanidin B2 (dimer), procyanidin C1 (trimer), cinnamtannin A2 (tetramer), and other oligometric procyanidins.
Sources:
1) Cocoa powder reduces LDL oxidative susceptibility and has beneficial effects on plasma HDL-cholesterol concentrations in humans
Seigo Baba, Naomi Osakabe,
American Journal of Clinical Nutrition, Vol. 85, No. 3, 709-717, March 2007
2)Dark chocolate consumption increases HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans.
Mursu J, Voutilainen S, Nurmi T, et al.
Free Radic Biol Med 2004;37:1351–9.
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