Poor blood vessel function is recognized as an early stage in the development process of cardiovascular diseases (CVD), including coronary artery disease.
CVD is one of the leading causes of morbidity, mortality, and disability in many parts of the world, especially in Western countries, and accounts for one-fifth of all mortality in the US.
The results of the research, which was published in the Journal of the American College of Cardiology (JACC), found that daily cocoa flavanol consumption more than doubled the number of circulating angiogenic cells (CACs) in the blood.
The study was supported by a grant from the American Heart Association, and an unrestricted research grant from Mars.
Blood vessel health
CACs have been shown to have vessel repair and maintenance functions, which can contribute to healthy blood vessels. The researchers said that increasing levels of CACs have also been associated with a decreased risk of death from CVD causes, citing a 2005 study published in the New England Journal of Medicine.
The authors of the JACC study claim that while other cutting-edge research has demonstrated that physical activity and experimental drug therapy can increase CAC levels, theirs is the first to demonstrate such benefits from a dietary intervention.
“Perhaps most importantly, for the first time, we found that cocoa flavanols might even directly mobilize important cells that could repair damaged blood vessels. The benefits are substantial, without any observed adverse effects," said one of the authors of the study, Christian Heiss, who is based at Heinrich-Heine University.
The researchers explained how they tested whether a 1-month dietary intervention with flavanol-containing cocoa in patients with coronary artery disease, medically managed according to currently accepted guidelines, leads to an improvement of endothelial dysfunction and whether this is associated with an enhanced number and function of CACs.
In a randomized, controlled, double-masked, cross-over trial, 16 CAD patients, aged between 61 and 67 received a dietary high-flavanol cocoa drink, containing cocoa made with the Mars Cocoapro process to "ensure consistency of flavanol levels", or a low-flavanol nutrient-matched control cocoa drink, twice a day for 30 days.
They explained how measurements were taken before initiation (day 0, pre-intervention), and the day after completion of each intervention (day 30, post-intervention). Pre- and post-intervention measurements were taken after overnight fasting and after 30 minutes of supine rest.
The cocoa drinks were well tolerated, and none of the patients experienced major adverse events, cardiovascular-specific events, or hospitalization during the study period, said the article.
The results showed that blood vessel function improved by 47 per cent compared to low-flavanol consumption.
“Our data support the concept that dietary flavanols, in addition to improving cardiovascular functions, can facilitate endogenous repair mechanisms that act synergistically with current medical therapy,” said the scientists.
The authors said that the outcomes of their trial also demonstrated that drinking high-flavanol cocoa significantly reduces systolic blood pressure, an important risk factor for heart disease and stroke.
Moreover, they pointed to a positive correlation observed between cocoa flavanols consumed and subsequent improvements in flow-mediated dilation (FMD), a measure of vessel health and its ability to relax.
The authors hold that further research involving long-term intervention trials examining the effects of high-flavanol diets on cardiovascular health and function is warranted as a result of their findings.
The health benefits of cocoa flavanols such as improvements to cardiovascular health have received much recognition in recent years, with positive findings from a number of studies impacting on consumer awareness.
But Mary Wagner, chief technology officer for Mars Botanical, a scientific division of Mars Inc, said that while flavanols are naturally abundant in cocoa, unless a processor is specifically measuring and carefully handling a product throughout the manufacturing process, there is no guarantee the product contains meaningful levels of the flavanols.
Mars and Barry Callebaut have both been aware of the detrimental effects of processing on the final flavanol content of products, prompting them to research new processing techniques to maximise the retention of cocoa flavanols and in February this year to announce a collaboration regarding quantifying flavanol levels in products.
And Gaby Tschofen, head of communications for Barry Callebaut, told this publication the two companies have jointly defined what the minimum content of flavanols should be in a final product - at least 140mg of cocoa flavanols per proportional serving of 50g.
Source: Journal of the American College of Cardiology
Published online ahead of print: doi:10.1016/j.jacc.2010.03.039
Title: Improvement of endothelial function with dietary flavanols is associated with mobilization of circulating angiogenic cells in patients with coronary artery disease
Authors: Heiss C et al