by Craig Weatherby
Chocolate has really been on a roll… and we don’t mean the Tootsie type.
Dozens of lab and clinical studies indicate that cocoa and other foods high in flavanol-type antioxidants exert artery-enhancing effects.
Flavanols appear to be particularly healthful members of the polyphenol family… a group of antioxidant “phyto-chemicals” found in most plant foods, from vegetables and fruits to beans, whole grains, and whole nuts.
The best food sources of flavanols are cocoa, berries, and tea. And the exceptional health potential seen in flavanols explains why these foods and beverages get more scientific attention than most.
Research in animals and people alike suggests that these flavanol-rich foods and beverages can produce improvements in blood flow, inflammation, oxidation, and other aspects of vascular health.
But it hasn’t been entirely clear how flavanols produce these benefits.
Despite being known as “antioxidants”—because they behave that way in the test tube—flavanols and other polyphenols generally don’t produce strong antioxidant effects in the body.
Instead, it appears that food-borne antioxidants exert “nutrigenomic” effects that influence our cells’ working genes in generally beneficial ways.
And a new clinical study may have detected a major way in which flavanols’ nutrigenomic effects work some specific wonders on artery health.
This new clinical evidence indicates that flavanol-rich cocoa may indirectly aid artery health and repair, with obvious implications for people suffering from or at risk of cardiovascular disease.
Clinical trial finds artery benefits in cocoa-tea-berry antioxidants
The small but rigorously designed trial (randomized, controlled, double-blind, cross-over) involved 16 cardiovascular patients aged 61 to 67.
They consumed one of two cocoa beverages twice a day for 30 days, alternating unknowingly between the two, with their blood and artery functions being measured periodically.
One beverage was rich in cocoa flavanols, and the other had only low levels. Neither the participants nor the researchers knew which was which until the study’s end.
(By the way, only a minority of cocoa and dark chocolate is truly flavanol-rich: see the sidebar titled “‘Dutching’ destroys most of chocolate’s health potential”.)
The researchers measured the volunteers’ endothelium function, circulating angiogenic cells, blood chemistry, heart rate and blood pressure, before, during and after the study.
The international team found that the function of the participants’ endothelium—as measured by dilation (width) of their arteries—improved by 47 percent more following consumption of the high-flavanol cocoa drink, versus the low-flavanol cocoa.
And production of angiogenic cells increased twice as much following consumption of the flavanol-rich drink compared to the low-flavanol drink.
The researchers also found that the high-flavanol beverage significantly decreased the participants’ blood pressure.
Findings help explain the artery benefits linked to cocoa, tea, and berries
Measurements made in the trial participants’ blood show that flavanols increase production of circulating angiogenic cells.
Produced in the bone marrow, these cells make their way into the blood stream where they develop into the endothelial cells that line arteries and vessels… and are used to repair areas damaged by inflammation, oxidized cholesterol, or other elements of arterial plaque.
According to UC Davis nutrition professor Carl Keen, “We were pleased, but not surprised, to find that when study participants consumed the flavanol-rich cocoa beverage, rather than a matched control drink with low levels of flavanols, they experienced a significant improvement in the function of the endothelium or lining of the blood vessel wall.”
Keen went on to say, “The flavanol-rich cocoa was strikingly effective in mobilizing the participants’ circulating angiogenic cells, which are thought to help repair the endothelium.”
And he made a key point about the comparative effects of cocoa, versus drugs and other interventions:
“The effect was on par with medical treatments involving statins and estrogen – and similar to the effects of lifestyle changes such as increasing exercise and stopping smoking, all of which are currently recommended for patients with coronary artery disease.”
This suggests that isolated flavanols or flavanol-rich foods might be used to help prevent or ameliorate cardiovascular disease… the common condition in which the arteries narrow as plaque builds up on the endothelium lining the inner artery walls.
Professor Keen and his colleagues suggested that future research should include long-term clinical studies that examine the effects of high-flavanol diets on cardiovascular health over time.
The clinical trial was a collaborative effort by researchers from UC Davis, UC San Francisco, Germany; and the candy company Mars Inc.
Heiss C, Jahn S, Taylor M, Real WM, Angeli FS, Wong ML, Amabile N, Prasad M, Rassaf T, Ottaviani JI, Mihardja S, Keen CL, Springer ML, Boyle A, Grossman W, Glantz SA, Schroeter H, Yeghiazarians Y. Improvement of endothelial function with dietary flavanols is associated with mobilization of circulating angiogenic cells in patients with coronary artery disease. J Am Coll Cardiol. 2010 Jul 13;56(3):218-24.
UC Davis (UCD). Flavanol-rich foods may help heart disease patients, study suggests. July 30, 2010. Accessed at http://news.ucdavis.edu/search/news_detail.lasso?id=9534