Modest amounts of chocolate may reduce the risk of stroke in men, judging by a new study from Sweden's famed Karolinska Institute.
“While other studies have looked at how chocolate may help cardiovascular health, this is the first … to find that chocolate may be beneficial for reducing stroke in men,” said lead author Susanna C. Larsson, Ph.D. (AAN 2012)
This news echoes results from a similar diet-health study in women, published last year by the same team.
These studies' positive findings fit with the conclusions published last year by researchers from England's University of Cambridge, who analyzed the results of earlier clinical trials and epidemiological studies.
Chocolate linked to reduced stroke risk in men
For the new study, 37,103 Swedish men – ranging from 49 to 75 years of age – were given a diet intake questionnaire that included questions about chocolate intake.
The men's health status was tracked for just over 10 years, and during which time 1,995 suffered a stroke.
Compared with those who ate no chocolate, the men who ate the most chocolate were 17 percent less likely to have suffered a stroke.
The Swedish team's analysis accounted for the effects of other foods linked to reduced stroke risk.
The men in the highest-intake group reported eating the equivalent of just over two ounces (63 grams) of chocolate per week.
The Swedish team also conducted a separate analysis of five studies that included 4,260 stroke cases.
That analysis showed that the risk of stroke for men and women who ate the most chocolate was 19 percent lower, compared to those who ate no chocolate.
And the risk of stroke was about 14 percent lower for every increase in weekly chocolate consumption of 50 grams (just under two ounces).
Prior study linked chocolate to stroke reduction in women
Last year, Larsson's team published the results of a similar study, in which they followed 33,372 women, aged 49 to 83 years, for 10 years.
They, too, answered questions about how often they had eaten chocolate – and 95 other foods associated with higher or lower stroke risk – during the year before.
Larsson's team separated the women into eight categories based on the amount of chocolate they reported eating: from none to three or more times a day.
The median intake (half ate more, half less) of the women in the highest-chocolate-intake group was about 2.3 ounces a week.
During the decade of follow-up, the women in the chocolate-loving group were 20 percent less likely to experience a stroke … even after adjusting for other lifestyle factors linked to reduced stroke risk.
And, as Dr. Larsson noted, “The protection started at [eating] more than 45 grams [about 1.5 ounces] a week.”
Both studies were supported by the Swedish Council for Working Life and Social Research, the Swedish Research Council/Committee for Infrastructure, and the Karolinska Institute.
Credit given to cocoa's rare antioxidants
According to Dr. Larsson, “The beneficial effect of chocolate consumption on stroke may be related to the flavonoids in chocolate. Flavonoids appear to be protective against cardiovascular disease through antioxidant, anti-clotting and anti-inflammatory properties. It's also possible that flavonoids in chocolate may decrease blood concentrations of bad cholesterol and reduce blood pressure.” (AAN 2012)
The uncommon flavanol-type antioxidants in cocoa appear to possess extraordinary health benefits, compared with other flavonoids.
(Green and white tea are the only other substantial sources of flavanols, and they pale by comparison to cocoa. See our sidebar, “Antioxidants or gene-influencers?”.)
That said, no one type of flavonoid is superior to consuming the combinations we get by eating a variety of whole plant foods.
This is because flavanols other flavonoid-type polyphenols seem to enhance each other's beneficial “nutrigenomic” effects in synergistic ways.
The study's outcome was rather surprising, since about 90 percent of the chocolate consumed in Sweden during the decade of the study was milk chocolate, which contains only about 30 percent cocoa solids
Given the likelihood that stroke protection stems from the flavanol-type antioxidants in cocoa, Larsson suggested that people choose dark chocolate (65 percent or more cocoa solids) over the milky kind.
Antioxidants or gene-influencers?
Whole plant foods abound in so-called “antioxidants” – primarily carotenes (carrots, squash, peppers, and wild salmon) and polyphenols, which occur in most plant foods … but most abundantly in berries, cocoa, tea, onions, beans, and whole grains.
Among other likely beneficial effects, these compounds' known “nutrigenomic” influences on gene switches and cell-signaling tend to moderate oxidation and inflammation.
The apparent health benefits of plant foods rich in carotenes and polyphenols almost certainly flow from these nutrigenomic effects, rather than from direct antioxidant effects in the body.
Evidence linking diets rich in fruits and vegetables to beneficial nutrigenomic effects may well explain why they're associated with lower risk of degenerative heart and brain diseases.
American Academy of Neurology (AAN). Chocolate: A Sweet Method for Stroke Prevention in Men? August 29, 2012. Accessed at http://www.aan.com/press/index.cfm?fuseaction=release.view&release=1099
Buitrago-Lopez A, Sanderson J, Johnson L, Warnakula S, Wood A, Di Angelantonio E, Franco OH. Chocolate consumption and cardiometabolic disorders: systematic review and meta-analysis. BMJ. 2011 Aug 26;343:d4488. doi: 10.1136/bmj.d4488. Review.
Larsson SC, Virtamo J, Wolk A. Chocolate consumption and risk of stroke: A prospective cohort of men and meta-analysis. Neurology. 2012 Aug 29. [Epub ahead of print]
Larsson SC, Virtamo J, Wolk A. Chocolate consumption and risk of stroke in women. J Am Coll Cardiol. 2011 Oct 18;58(17):1828-9.