Eating a daily dose of cocoa or dark chocolate - rich in antioxidants called flavanols - may lead to a slight drop in blood pressure for a short period of time, a review of studies concluded.
Researchers analyzed 20 studies published over the last decade and found that people who ate flavanol-rich cocoa products every day for a few weeks saw their blood pressure drop by about two or three points.
While that's far less than the reduction people taking blood pressure lowering medication could expect, the researchers noted it is similar to the effect of dietary changes or exercise. While a small amount of dark chocolate appears modestly beneficial, too much will contribute excess calories to one's diet.
For the analysis, Australian researchers searched several online databases to find randomized controlled trials - considered the "gold standard" of medical research - that compared people eating flavanol-rich cocoa products to people eating low-flavanol cocoa powder or products that contained none of the plant compounds.
Flavanols - which are also found in foods such as green tea, berries and red wine - are linked to nitric oxide production in the body. Nitric oxide helps relax blood vessels, which reduces blood pressure.
The 20 studies included in the review followed people who were generally healthy. Of 856 participants, 429 ate between 3 grams (g) and 100 g of dark chocolate or cocoa that contained anywhere from 30 milligrams (mg) to 1080 mg of flavanols, daily.
The other 427 people were put in comparison groups that ate low-flavanol cocoa powder or products that did not contain any flavanols.
At the end of the studies, those who ate the flavanol-rich dark chocolate or cocoa product saw their systolic blood pressure fall by roughly 2.8 mm Hg while their diastolic fell by 2.2 mm Hg.
Since most of the studies included in the analysis only followed people over a few weeks, the researchers cannot say what, if anything, would happen to the blood pressure of a person who ate cocoa or chocolate over months or years.
These findings also don't say if eating cocoa or dark chocolate led study participants to have fewer heart attacks or strokes, both of which are linked to high blood pressure.
In addition, there's no telling how much cocoa or chocolate would be best, because each study used different amounts.
The effects also seemed greater in younger people compared to older adults. The researchers said that's not surprising since blood vessels may become less elastic as people age, and therefore less likely to react to nitric oxide.
While a small amount of dark chocolate appears modestly beneficial, too much can contribute excess calories to one's diet.
SOURCE: The Cochrane Library, online August 14, 2012.
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