Eating just one square of chocolate a day can cut the risk of heart attack and stroke by 39%, researchers have said.
Eating 7.5g of chocolate daily also leads to lower blood pressure, the study found.
Researchers in Germany followed 19,357 people aged between 35 and 65 for at least a decade.
Those who ate the most amount of chocolate - an average of 7.5g a day - had lower chances of heart attacks and stroke than those who ate the least amount (1.7g a day on average).
The difference between the two groups amounted to 6g of chocolate - less than one square of a 100g bar.
The study, published in the European Heart Journal, concluded that if those people who ate the least chocolate increased their intake by 6g a day there would be fewer heart attacks and strokes.
Of those who ate the least chocolate, there were 219 strokes or heart attacks per 10,000 people but there could be 85 fewer if they ate 7.5g a day on average, researchers said.
Those who ate the most chocolate had a 27% reduced risk of heart attacks and nearly half (48%) the risk of strokes compared with those eating the least amount.
Eating chocolate lowered blood pressure, which accounted for some of the reduced risk, but falls were seen in heart attacks and strokes even when this was taken into account.
Dr Brian Buijsse, a nutritional epidemiologist at the German Institute of Human Nutrition, Nuthetal, Germany, who led the research, said: “If the 39% lower risk is generalised to the general population, the number of avoidable heart attacks and strokes could be higher because the absolute risk in the general population is higher.”