Chocolate reduces stroke risk in men

Pauline Anderson

August 30, 2012

Stockholm, Sweden - A new study shows that men who consume the most chocolate have a 17% lower risk of stroke than those who consume the least [1]. A meta-analysis included in the study showed an overall 19% decreased risk of stroke for the highest consumers of chocolate—male and female—compared to those who ate the least.

But while results "suggest that chocolate consumption is inversely associated with risk of stroke," further research is needed to confirm these findings before any recommendations about chocolate consumption can be given, according to the authors, led by Dr Susanna C Larsson (Karolinska Institute, Stockholm, Sweden).

The study is published in the September 28, 2012 issue of Neurology.

Chocolate categories

The study included 37 103 men from the Cohort of Swedish Men, a prospective study that began in 1997 when all men aged 45 to 79 years residing in two counties in central Sweden were asked to provide detailed information on diet and other lifestyle factors. Researchers assessed chocolate consumption using a self-administered food frequency questionnaire that included 96 foods and beverages.

For chocolate consumption, respondents could choose from eight categories, ranging from never to eating chocolate three or more times per day. To determine consumption in grams, researchers multiplied the frequency of consumption by four age-specific portion sizes to arrive at quartiles of chocolate consumption: <12.0 g/week (median 0 g); 12.0 to 19.5 g/week (median 12.5 g); 19.8 to 51.3 g/week (median 38.4); and >51.8 g/week (median 62.9).

By linking the study population to the Swedish hospital-discharge register, researchers identified incidence cases of stroke. They classified stroke events as cerebral infarction, intracerebral hemorrhage, subarachnoid hemorrhage, and unspecified stroke.

From 1998 to 2008, there were 1995 cases of first stroke, including 1511 cerebral infarctions, 321 hemorrhagic strokes, and 163 unspecified strokes. Compared with men in the lowest chocolate-consumption group, those who ate the most were on average younger and less likely to be current smokers. They also tended to be slightly leaner and to consume more alcohol, red meat, fruits, and vegetables but less fish.

Adjusted risk

After adjustment for a number of factors, including age, education, smoking status, body-mass index, physical activity, aspirin use, history of hypertension, and atrial fibrillation, high chocolate consumption was associated with a statistically significant lower risk of total stroke.

Compared with men in the lowest quartile of consumption, those in the highest category had a reduced risk for stroke of 17%. Results were similar for cerebral infarction and for hemorrhagic stroke.

Stroke risk with highest vs lowest chocolate consumption

Outcome
Relative r isk (RR)
95% C I
p
Stroke
0.83
0.70-0.99
0.08
Cerebral i nfarction
0.83
0.69-1.01
0.14
Hemorrhagic s troke
0.84
0.56-1.25
0.42

The age-standardized incidence rates of stroke were 85 per 100 000 person-years for those consuming the least chocolate and 73 per 100 000 person-years for those in the highest quartile.

In an analysis stratified by history of hypertension, an inverse relation between chocolate consumption and risk of total stroke was observed in men without hypertension (RR 0.76; 95% CI 0.62-0.93) but not in men with a history of hypertension (RR 1.04, 95% CI 0.77-1.41; p for interaction=0.04)

The results were unchanged after additional adjustment for history of hypercholesterolemia.

Meta-analysis

The researchers also carried out a meta-analysis that included results from the current study as well as four other prospective studies assessing the association between chocolate consumption and stroke risk. In this analysis, which included 4260 stroke cases, the overall relative risk of stroke for the highest vs lowest category of chocolate consumption was 0.81 (95% CI 0.73-0.90), or a 19% reduction in risk.

There was also a dose response meta-analysis using the same methods.

Chocolate is a rich source of flavonoids that may protect against cardiovascular disease through antioxidant, antiplatelet, and anti-inflammatory effects. Flavonoids may also lower blood pressure, increase HDL cholesterol, and improve endothelial function. Chocolate also contains antioxidant-rich caffeine, albeit low amounts.

Among the limitations of the study was that chocolate consumption was self-reported and measured at only one time point. Another is that information on the type of chocolate consumed was not available. As a result, any association with dark chocolate, previously been linked to health benefits, couldn't be examined, but in general, about 90% of chocolate consumed in Sweden is milk chocolate, containing about 30% cocoa solids, they write.

The authors stress also that chocolate is high in sugar, saturated fat, and calories and should be consumed in moderation.

Confirms observations

Reached for a comment, Dr Gustavo Saposnik (University of Toronto, ON) said the present study confirms previous observations, including those of his own systematic review, that eating chocolate is associated with a lower risk of stroke.

Results of his and his colleagues' review, presented at the American Academy of Neurology 2010 Annual Meeting, showed that in one study, there was a 22% reduction in stroke risk for subjects who had one serving of chocolate per week, and in another, there was a 46% reduction in stroke mortality from weekly consumption of flavonoids in 50 g of chocolate vs no consumption. However, the number of studies looking at the relationship between chocolate consumption and stroke risk and included in the analysis was small.

Saposnik found it interesting that in the current study, even very low chocolate consumption of a median 62.9 g/week was associated with a 17% stroke reduction.

He noted that the study was limited by its use of questionnaires that were not specifically intended to target the association between chocolate and risk of stroke. This, he said, could introduce the potential risk of misclassification. As well, he said that the study had limited information about the composition of the chocolate consumed.

For Saposnik, the strength of the study was the meta-analysis that included five studies.

The study was supported by the Swedish Council for Working Life and Social Research , the Swedish Research Council/Committee for Infrastructure , and the Karolinska Institute. The authors report no disclosures.

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