In Sweden, even ‘milk’ chocolate contains about 30% cocoa – while in the U.S. chocolate is officially ‘dark’ at only 15% cocoa content.
More data indicating that habitual consumption of chocolate (cocoa) may significantly lower the risk of all types of stroke has emerged from a Swedish study tracking the diet and health of more than 33,000 women.
The women, ages 49 to 83, who ate the most chocolate – 66.5 grams each week, or about two chocolate bars – had a 20% lower risk of having a stroke over the past 10 years, according to a report published online Oct 10 by the Journal of the American College of Cardiology.
Although previous studies have shown a link between chocolate consumption and stroke,(1) the authors say this is the first to assess the potential cardiovascular benefits of chocolate across different stroke types. It also includes a larger number of stroke cases to examine relationship with chocolate intake.
“Even consuming a relatively small amount of chocolate had quite a large impact on stroke risk,” said lead investigator Susanna Larsson, PhD, of the National Institute of Environmental Medicine, Stockholm. “But women reporting the highest amount of chocolate consumption – equivalent to about two chocolate bars a week – had a significantly reduced risk of stroke, suggesting that higher intakes are necessary for a potentially protective effect.”
While chocolate consumption was inversely associated with both cerebral infarction (an ischemic stroke resulting from a disturbance or blockage in the blood vessels supplying blood to the brain) and hemorrhagic stroke (when a blood vessel in the brain ruptures), the association was slightly stronger for hemorrhagic stroke for reasons that remain unknown.
“The difference between stroke subtypes was not significant, and deserves further study,” said Dr. Larsson. “It does appear from the data that the association between chocolate consumption and stroke is expected to be stronger with higher concentration of cocoa in the chocolate.”
Flavonoids as Protective, Preventive
Chocolate is presumed to have heart benefits due to the flavonoids (polyphenolic compounds) in cocoa that have antioxidant properties.
• Antioxidants protect the body from damage caused by free radicals and can suppress oxidation of low-density lipoprotein or “bad” cholesterol, which can cause damage to the cardiovascular system.
• Dark chocolate consumption has also been shown to reduce blood pressure, a strong risk factor for stroke, as well as to improve endothelial and platelet function and to ameliorate insulin resistance.
Still, Dr. Larsson cautions that chocolate and especially chocolate bars are high in sugar, fat and calories and should therefore be consumed in moderation. “Choose dark chocolate, which is usually lower in sugar and has higher flavonoid content,” she said.
The Swedish Study
The present study included women enrolled in the population-based Swedish Mammography Cohort. Women were asked to indicate how often on average they had consumed chocolate and 95 other foods during the previous year using a validated food-frequency questionnaire.
Researchers then stratified the women into categories ranging from never eating chocolate to those who indulged three or more times a week and examined the risk of stroke over a mean follow up of 10.4 years, adjusting for major risk factors associated with stroke.
Cocoa Concentration in the US
Dr. Larsson says more large prospective studies need to assess the association between chocolate and stroke, and to distinguish between the vascular benefits of milk versus dark chocolate. This is of special importance for studies conducted in the United States as the cocoa concentration in the chocolate sold in the US on average have lower cocoa concentration
“In Sweden, milk chocolate has a higher cocoa concentration than dark chocolate sold in the United States,” she says. “So, we would expect U.S. chocolate to offer fewer health benefits and contain more fat and calories per serving.”
Swedish milk chocolate contains roughly 30% cocoa; but chocolate in the U.S. only has to have 15% cocoa to qualify as sweet dark chocolate, according to authors.
1. A meta-analysis published Aug 29 by the British Medical Journal – “Chocolate consumption and cardiometabolic disorders” – found that people who ate the most chocolate had a 37% lower risk of cardiovascular disease and a 29% lower risk of stroke compared with individuals who ate the least amount of chocolate. These data had been presented before publication at the European Society of Cardiology 2011 Congress.
Source: American College of Cardiology news release, Oct 11, 2011