Flavonoid-rich dark chocolate may improve the function of the cells lining blood vessels and help control blood pressure in younger, but not older, hypertensives, says a new study.
A seven day study involving the consumption of 75 grams per day of dark chocolate with hypertensive subjects showed that the best response was observed in younger people. Non-responders tended to be older, report scientists from the Federal University of Rio de Janeiro in Brazil.
Writing in the International Journal of Hypertension , the researchers stated: “The intake of dark chocolate significantly improved endothelial function and reduced blood pressure in some individuals who were younger hypertensive patients with impaired endothelial function in spite of lower cardiovascular risk.”
The health benefits of polyphenols from cocoa have been gathering increasing column inches in the national media. To date studies have reported potential benefits for cardiovascular health, skin health, and even brain health.
The majority of science into the potential benefits of cocoa have revolved around cardiovascular benefits of the flavanols (also known as flavan-3-ols or catechins), and particularly the monomeric flavanol (-)epicatechin.
Swiss choc giant Barry Callebaut recently enjoyed success in Europe with its EFSA-approved cocoa flavanol health claim being written into EU law by the European Commission yesterday. The claim says that eating 200 mg of cocoa flavanols daily either from cocoa beverages or dark chocolate contributes to normal blood flow.
The new study appears to show that not everyone will benefit from the cardiovascular effects, particularly people with elevated blood pressure (hypertension). The Brazilian researchers recruited 21 hypertensive subjects, aged between 40 and 65, and gave them a daily 75 gram dose of dark chocolate, which provided 3202 mg of polyphenols in the total daily dose.
After the seven days of chocolate consumption, the subjects were classified as responders or non-responders, depending on if a 1% change in flow mediated dilation (FMD) occurred or not. FMD is a measure of a blood vessel's healthy ability to relax.
Results showed that responders were younger (average age of 54 compared to 61 for non-responders), and had lower pulse pressure values.
The reductions in blood pressure that were recorded for the responders were “relatively small [but] clinically significant”, said the researchers. One week of dark chocolate consumption reduced systolic blood pressure from 140 to 131 mmHg and diastolic blood pressure from 85 to 82 mmHg.
“It has been found that a reduction of 3 mmHg in systolic BP can reduce relative risk of death from stroke by 8%, from cardiovascular disease in general by 5%, and overall all-cause mortality by 4%,” they said. “In our study, the responder group also demonstrated a reduction in aortic systolic blood pressure and pulse pressure, although not reaching statistical significance. This result may suggest a less prominent effect of dark chocolate on vascular stiffness parameters.
“There is as yet no way to identify those who will benefit from dark chocolate consumption, but the present study provides data that could be examined in larger randomized controlled studies for the selection of subjects likely to benefit from increased intakes of dark chocolate,” they concluded.
Source: International Journal of Hypertension
Published online, doi: 10.1155/2013/985087
“Characterisation of Hypertensive Patients with Improved Endothelial Function after Dark Chocolate Consumption”
Authors: J. d'El-Rei, A.R. Cunha, A. Burlá, M. Burlá, W. Oigman, M. Fritsch Neves, A. Virdis, F. Medeiros