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Effect of cacao and dark chocolate on cardiovascular disease

Consumption of cacao and chocolate has been linked to a reduced risk of cardiovascular disease. The health benefits of phytochemical-rich cacao have received much recognition in recent years and food manufacturers are using high cacao content as a means of differentiation.

In vitro studies suggest that the health effects of cacao flavonoids include are the result of antioxidant effects, modulation of cell signaling and gene expression, alterations of certain cell membrane properties and receptor functions and inhibition of several enzyme activities. A meta analysis conducted in 2005 by Ding and co-workers showed that cocoa and chocolate may exert beneficial effects on cardiovascular protection via effects on lowering blood pressure, anti-inflammation, anti-platelet function, higher HDL and decreased LDL oxidation [1]. But a more recent study published in The American Journal of Clinical Nutrition was less optimistic about the possible hearth health benefits of cacao [2]. Crew and co-workers at the State University, Blacksburg, USA, failed to support the beneficial effects of short-term dark chocolate and cocoa consumption on any of the neuropsychological or cardiovascular health-related variables they investigated. They even found that the consumption of dark chocolate and cocoa was associated with significantly higher pulse rates.

Mostofsky and co-workers at the Harvard Medical School, Boston, found a protective effect of moderate consumption of chocolate in a prospective cohort study of 31,823 women aged 48 to 83 years [3]. They investigated the association between chocolate intake and incidence of heart failure and found that a moderate consumption of chocolate resulted in lower heart failure rates, but those consuming 3 or more servings per week showed even higher heart failure rates. Davison and co-workers at the University of South Australia tried to establish a dose-related effect of flavanol-rich cacao on blood pressure 20 postmenopausal women and 32 men [4]. The participants were randomized and instructed to consume daily a reconstituted cocoa beverage containing 33, 372, 712 or 1052 mg of cacao flavonols for 6 weeks in a double-blind, parallel comparison. The researchers found significant reductions in systolic, diastolic and mean arterial blood pressure in the group using the highest dose of cacao. They concluded that their results support previous evidence for cacao flavanoids to lower blood pressure, but that more research is needed to establish the most effective dose and food matrix. Another study conducted at the same university, but lead by Berry, explored the effects of cacao flavanoids on endothelium-dependent flow-mediated dilatation [5]. Impaired endothelial vasodilatation may contribute to the increased blood pressure during exercise in overweight individuals. The researchers found that after exercise blood pressure was much lower and flow-mediated dilatation was higher in participants consuming high-flavanol cacao beverage, compared to those consuming low-flavanol cacao beverage. They conduced that cacao flavanols may decrease cardiovascular risk and enhance the cardiovascular benefits of exercise in overweight individuals, by facilitating vasodilation and attenuating exercise-induced increases in blood pressure. A case-control study done in Italy showed that the risk for myocardial infarction was inversely associated to chocolate consumption. The group that ate more than three portions of chocolate per day showed a 77% decrease in risk for myocardial infarction compared to the group that consumed less than one [6]. A Dutch study explored the effect of habitual cocoa intake on blood pressure and cardiovascular mortality [7]. The researchers took data from 470 elderly men participating in the Zutphen Elderly Study and found that the mean systolic blood pressure and mean diastolic blood pressure were respectively 3.7 mm Hg and 2.1 mm Hg lower in the fertile with highest cacao consumption compared with the lowest tertile. Compared with the lowest tertile of cocoa intake, the risk for men in the highest tertile was 50% for cardiovascular mortality.

[1] Chocolate and prevention of cardiovascular disease: a systematic review. Nutr Metab (Lond). 2006 Jan 3;3:2.
[2] A double-blind, placebo-controlled, randomized trial of the effects of dark chocolate and cacao on variables associated with neuropsychological functioning and cardiovascular health: clinical findings from a sample of healthy, cognitively intact older adults. Am J Clin Nutr. 2008 Apr;87(4):872-80.
[3] Chocolate intake and incidence of heart failure: a population-based prospective study of middle-aged and elderly women. Circ Heart Fail. 2010 Sep 1;3(5):612-6. [4] Dose-related effects of flavanol-rich cacao on blood pressure. J Hum Hypertens. 2010 Sep;24(9):568-76.
[5] Impact of cocoa flavanol consumption on blood pressure responsiveness to exercise. Br J Nutr. 2010 May;103(10):1480-4.
[6] Response to Chocolate, well-being and health among elderly men: chocolate and acute myocardial infarction in a case-control study from Italy. Eur J Clin Nutr. 2009;63:588589. [7] Cocoa intake, blood pressure, and cardiovascular mortality: the Zutphen Elderly Study. Arch Intern Med. 2006 Feb 27;166(4):411-7.

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