A systematic review on the role of chocolate in the prevention of cardiovascular diseases

Abstract

Background: Research studies in recent years suggested possible role of dark chocolate in preventing cardiovascular diseases due to its high flavonal and procyanidins contents. Whether there is clear clinical benefit and the mechanisms mediating such benefits is controversial.

Objective: This systematic review aims to comprehensively examine the current clinical evidence regarding effectiveness and the possible mechanisms of chocolate in reducing the risk and / or surrogate markers of cardiovascular diseases.

Methods: Comprehensive electronic literature search was performed using Ovid, Medline and Cochrane database. Only English language literatures published during year 1950 - 2010 were reviewed. All intervention studies and observational studies of adult human subjects taking white or dark chocolate in relation to outcomes of cardiovascular risk were included. All review articles

and meta-analysis were also included. Clinical diagnosis of cardiovascular disease and surrogate markers including blood pressure, vascular endothelial function as measured by flowed mediated vasodilation, and blood biomarkers such as lipid profile were studied as outcome variables.

Results: The review outlines recent observational and interventional studies and meta-analysis to give an overview of the topic. For observational studies, a cohort studies and two case control studies were found. The observational studies showed that dark chocolate consumption was inversely associated with blood pressure, cardiovascular mortality and C-reactive protein. All interventional studies searched showed that dark chocolate increased FMD and improved platelet function. However, the effects of cocoa on intermediate outcomes such as blood pressure, antioxidant capacity and inflammatory marker changes were inconsistent among interventional studies. Three interventional studies indicated that there was a dose-dependent improvement in immediate outcome variables after 1 month or even 2 hours acute consumption of dark chocolate with procyanidins or cocoa drink with flavonol. However, publication bias and potential conflict of interests may be a potentially important factor in interpreting study results in the current literature.

Conclusions: There are some clinical and scientific evidences that consumption of dark chocolate produces positive cardiovascular benefits. A small amount of dark chocolate may be good for the heart. However, gaps in our knowledge such as a lack of long-term RCT in clinical outcomes must be filled in before recommending habitual dark chocolate consumption for reduction of cardiovascular risk.