Eating a moderate amount of European chocolate each week may help prevent stroke, a study of Swedish men suggests.

The study in Wednesday's issue of the journal Neurology suggested that men who ate one-third of a cup of chocolate chips had a lower risk of stroke than those who didn’t eat any of the sweet treat.

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European chocolate often contains more cocoa solids than chocolate in North America. (Pilar Olivares/Reuters)

Those eating the highest amount of chocolate had a 17 per cent lower risk of stroke, or 12 fewer strokes per 100,000 person-years compared with those who ate no chocolate. Person-years is the total number of years that each man was under observation.

"These findings suggest that moderate chocolate consumption may lower the risk of stroke," Susanna Larsson of the Karolinska Institute in Stockholm and her co-authors concluded.

"Because chocolate is high in sugar, saturated fat and calories, it should be consumed in moderation."

The study included 37,103 men aged 49 to 75 who filled in questionnaires about how often they ate nearly 100 foods and drinks.

Over 10 years, 1,995 cases of stroke occurred but there was no difference in the association by type of stroke.

Compared with men who said they ate the least amount of chocolate, those who ate the most were younger on average and more likely to have a university education and to use Aspirin but were less likely to be current smokers and have a history of hypertension or the heart condition atrial fibrillation.

A review of similar studies that was part of the research also suggested a 19 per cent decrease in risk of stroke with chocolate consumption.

When the researchers considered history of hypertension in their analysis, the association between chocolate consumption and stroke remained the same, they said, noting those with a history of high blood pressure when the study began may have had normal levels because they were treated for it.

The flavonoids in chocolate could have blood pressure lowering-effects, based on short-term feeding trials. Ingredients in chocolate are also thought to have antioxidant and anti-inflammatory effects.

In Sweden, about 90 per cent of the chocolate consumed is milk chocolate, Larrson said. Those sweets tend to be richer in cocoa solids than the most popular types of chocolate in North America.

The researchers estimated that chocolate contributed 4.9 per cent of antioxidants in participants' diets. Apples and pears were a richer source at 6.1 per cent as were oranges, 6.2 per cent.

One of the limitations of the study is that people self-reported their chocolate consumption and they were only asked about it when the research began and it’s possible some people changed their intake.

The researchers did not have information about the type of chocolate that people ate.

Last year, Larsson’s team reported that women who have two small bars of chocolate a week, about 66.5 grams, were about 20 per cent less likely to suffer a stroke than those who abstained from eating it.

The study was funded about Swedish Council for Working Life and Social Research and the Swedish Research Council.