Eating just one square of chocolate a day can cut the risk of heart attack and stroke by 39%, researchers said today.
Eating 7.5g of chocolate daily also leads to lower blood pressure, a 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: "People who ate the most amount of chocolate were at a 39% lower risk than those with the lowest chocolate intakes.
"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."
However, he warned people against eating too much chocolate and putting on weight or cutting down the amount of healthy foods they eat.
"Small amounts of chocolate may help to prevent heart disease, but only if it replaces other energy-dense food, such as snacks, in order to keep body weight stable," he said.
Cocoa beans contain flavanols, which are thought to have an effect on lowering blood pressure.
The experts said dark chocolate has more flavanols than milk chocolate and is therefore likely to be more beneficial.
Frank Ruschitzka, from the European Society of Cardiology (ESC), said: "Basic science has demonstrated quite convincingly that dark chocolate particularly, with a cocoa content of at least 70%, reduces oxidative stress and improves vascular and platelet function.
"However, before you rush to add dark chocolate to your diet, be aware that 100g of dark chocolate contains roughly 500 calories.
"As such, you may want to subtract an equivalent amount of calories, by cutting back on other foods, to avoid weight gain."
Victoria Taylor, senior heart health dietician at the British Heart Foundation, said: "This sounds like a dream for chocolate lovers and just in time for Easter too, but it's important to read the small print with this study.
"The amounts consumed on average by even the highest consumers was about one square of chocolate a day or half a small chocolate Easter egg in a week, so the benefits were associated with a fairly small amount of chocolate.
"Some people will be tempted to eat more than one square, however.
"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.
"So whilst chocolate, in moderation, can form part of a heart healthy diet it is important to remember to include a variety of other foods including fruit and vegetables and oily fish, as well as getting out and being active for at least 30 minutes a day."
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