Researchers in Germany assessed the chocolate intake of 19,357 middle-aged people over eight years and found those who ate the most chocolate had lower BP.
Those who ate about 7.5g of chocolate per day had a 27 per cent reduced risk of MI and a 48 per cent reduced risk of stroke, compared with those who ate about 1.7g. Increasing chocolate consumption by 6g in the lower intake group would have led to 85 fewer heart attacks or strokes per 10,000 people.
What is the basis of this effect?
Previous studies have reported that cocoa consumption raises cerebral blood flow, and this may explain the reduced risk of stroke, the authors said.
Research has also suggested that chocolate may benefit endothelial and platelet function, which could explain the reduced CVD risk.
Study lead Dr Brian Buijsse said: 'Flavanols appear to be the substances in cocoa responsible for improving the bioavailability of nitric oxide from the cells that line the inner wall of blood vessels.' Nitric oxide gas causes smooth muscle cells of blood vessels to relax and widen and this may contribute to lower BP.
Should advice change?
Dr Buijsse said it was important that eating chocolate did not increase a person's overall intake of calories.
The authors said that while it was 'tempting to indulge' in chocolate because of the benefits shown, more research was needed before it is used in diets aimed at preventing CVD.
The British Heart Foundation stressed that small quantities of chocolate had proved beneficial in the study. Victoria Taylor, senior heart health dietician, said: 'Chocolate has high amounts of calories and saturated fat, which are linked to weight gain and raised cholesterol levels: two of the key risk factors for heart disease.'
She concluded that while chocolate in moderation can form part of a healthy diet, a varied diet and regular exercise are also important.