How chocolate helps the heart

Recent studies have suggested that chocolate can be considered a heart-healthy food. Chocolate appears to

• decrease inflammation in the body,
• make the blood less likely to clot (by decreasing platelet clumping),
• lower blood pressure (by relaxing blood vessel walls),
• help prevent hardening of the arteries (by inhibiting the oxidation of LDL [“bad”] cholesterol),
• increase HDL (“good”) cholesterol levels, and
• improve insulin sensitivity.

So, we know that eating chocolate may lower the chance of developing risk factors associated with heart disease and diabetes, but to what degree does eating chocolate actually help prevent these conditions? That is the question that researchers from the UK and Colombia attempted to answer in a systematic review of the scientific literature.

The review authors hoped to find controlled studies that looked at the association between eating chocolate and the risk of cardiovascular disease and diabetes, but these were hard to come by. In the end, seven observational studies that involved a total of 114,009 participants were selected for analysis. Since none of the studies in the analysis was controlled, the results can only suggest (not prove) whether chocolate can play a role in preventing heart disease or diabetes.

What the studies found

The review compiled the results from the separate studies and summarized the findings. Compared with people who ate the least amount of chocolate (which varied by study), those who ate the most showed:

• A 37% reduced risk for overall cardiovascular disease
• A 31% reduced risk for diabetes
• A 29% reduced risk for stroke

No association was found between eating chocolate and the risk of heart failure.

Since heart disease and diabetes are increasingly prevalent worldwide, the authors suggeste that, “chocolate could provide a natural, convenient, and generally welcome prophylactic agent against the growing epidemic of cardiometabolic disorders.”

Chocolate eaters needed (they hope!) for more studies

Although the studies included in the review cannot prove that chocolate consumption causes a reduction in the risk of these conditions, they do provide more evidence of a link. Hopefully, this will encourage other investigators to design more studies aimed at confirming the positive associations found in this review.

(BMJ 2011;343:doi:10.1136/bmj.d4488)