The largest observational study indicated that individuals who ate the most chocolate – around 7.5 g per day or 1 small square of a 100-g bar– had a 39% lower risk of myocardial infarction (MI) and stroke than individuals who ate a small amount of chocolate (1.7 g per day).
The study shows that habitual consumption of chocolate can lower risk of heart disease and stroke. The risk reduction is stronger for stroke than for MI, because chocolate has pronounced effect on blood pressure (BP) and BP is a higher risk factor for stroke than for MI.
The study followed 19,357 people, aged between 35 and 65, who were participants in the Potsdam arm of the European Prospective Investigation into Cancer (EPIC).
At the start of the study (1994-1998), individuals received body check-up (including blood pressure, height and weight measurements) and were asked about their diet, lifestyle and health, including how frequently they ate 50-g bars of chocolate. In the 8 years follow-up until December 2006, the participants were asked whether they had a heart attack or stroke.
During the eight years, people in the top quartile of chocolate consumption (around 7.5g of chocolate a day) had a blood pressure that was about 1/0.9 mmHg (systolic/diastolic) lower than those in the bottom quartile.
Furthermore, people in the top quartile had a 27% reduction in MI risk and 48% reduction in the risk of stroke, compared with those in the lowest quartile.
Mechanism by which chocolate reduces the risk of cardiovascular death and stroke include the release of nitric oxide which contributes to lower BP and improves platelet function.
However, readers should be cautious not to eat too many chocolate because many chocolate also contains high amounts of calories and fat, two of the key risk factors for heart disease. When choosing chocolate, it is better to choose dark chocolate (since it is the coca content that is beneficial) and to eat a small amount (one square of a 100-g bar) a day.
Source: March 21, 2010 issue of the European Heart Journal.
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