Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flavonoid-rich dark chocolate boosts blood vessel function, study suggests

01.06.2004


UCSF scientists are publishing sweet results of a study examining chocolate’s effects on blood vessel function in healthy people. The team reports that small daily doses of flavonoid-rich dark chocolate consumed over a two-week period improved blood vessels’ ability to dilate, or expand. They also report that a particular flavonoid thought to be beneficial for blood vessel function, epicatechin, was absorbed at high levels in the blood.

"This is the longest clinical trial to date to show improvement in blood vessel function from consuming flavonoid-rich dark chocolate daily over an extended period of time," says lead author Mary Engler, PhD RN, professor of physiological nursing in the UCSF School of Nursing. "It is likely that the elevated blood levels of epicatechin triggered the release of active substances that vasodilate, or increase, blood flow in the artery. Better blood flow is good for your heart." The study appears in the June issue of the Journal of the American College of Nutrition.

Previous clinical studies have shown the beneficial effects of chocolate on the function of blood vessel endothelium [the inner lining of blood vessels] after either a single dose or several doses of chocolate over a few days.



Flavonoids, a group of chemical compounds with antioxidant properties, are derived from a variety of plants. They have been shown to promote several beneficial effects in the cardiovascular system, including decreasing oxidation of LDL cholesterol (a harmful process that allows cholesterol to accumulate in blood vessels); inhibiting aggregation of blood platelets (which contributes to the risk of blood clots that produce stroke and heart attack); and decreasing the body’s inflammatory immune responses (which contribute to atherosclerosis).

In the randomized, double-blind, placebo-controlled study, eleven people received 46 grams (1.6 ounces) of dark, flavonoid-rich chocolate every day for two weeks, while ten others received dark chocolate with low-flavonoid content. At the end of the two-week trial, Engler and her team recorded the ability of the principal artery in the arm, the brachial artery, to expand. The brachial artery’s dilation measurements correlate well with those of the coronary arteries that supply the heart.

The team measured the artery’s "flow-mediated dilation" using ultrasound to obtain the brachial artery’s diameter immediately after deflating a blood pressure cuff that had been inflated for five minutes on study participants’ forearms. "This measurement actually gives us a "videoclip" of an individual’s vascular health, and can be helpful in determining whether one is at risk for heart disease," says Engler. The induced increase in blood flow after the cuff is deflated causes release of many dilator substances, such as nitric oxide and prostanoids, which relax, the artery. Flow-mediated dilation is expressed as the percentage maximum change in vessel diameter from baseline.

In the high-flavonoid group, flow-mediated dilation increased from an initial 10.2 percent at the beginning of the study to 11.5 percent at the end of the study, while in the low-flavonoid group dilation decreased from 10.7 percent at the beginning of the study to 9.74 percent at the end of the study. The mean increase in flow-mediated dilation between the two groups showed a statistically significant difference, says Engler.

"Improvements in endothelial function [the ability of the artery to dilate] are indicative of improved vascular health and a lower risk for heart disease," Engler says. "Arteries that are able to dilate more have increased blood flow, and this is especially important for the heart."

Engler and her group also found that concentrations of the cocoa flavonoid epicatechin soared in blood samples taken from the group that received the high-flavonoid chocolate, rising from a baseline of 25.6 nmol/L to 204.4 nmol/L. In the group that received the low-flavonoid chocolate, concentrations of epicatechin decreased slightly, from a baseline of 17.9 nmol/L to 17.5 nmol/L.

The authors also found that the participants did not have increased blood cholesterol levels after these daily snacks of chocolate for two weeks.

The study was funded by the UCSF School of Nursing. Chocolate for the study was provided by the American Cocoa Research Institute, Vienna, VA.

In the past five years, scientists have developed increasingly accurate methods of detecting flavonoids. Only a few years ago, dark chocolate was found to contain more flavonoids than any other food that’s been tested so far, including such flavonoid-rich foods as green and black tea, red wine and blueberries, says Engler. "Many people don’t realize that chocolate is plant-derived, as are the fruits and vegetables recommended for a healthy heart. Chocolate is made from the cacao bean found in the fruit pod of the cacao tree (Theobroma cacao)."

Standard manufacturing of chocolate destroys about a quarter to half of its flavonoids. Now, some companies are using processing methods with reduced heat and alkalization, which can preserve as much as 70 percent to 95 percent of the chocolate flavonoids.

The UCSF study suggests that the beneficial effects of eating small doses of chocolate can be found in eating chocolate with higher amounts of cocoa , i.e., at least seventy percent cocoa content, says Engler. Additional information on current chocolate research can be found at the Chocolate Information Center website (http://www.chocolateinfo.com) sponsored by Mars, Inc, she says.

The current study supports many other studies that have shown benefits from cocoa flavonoids, Engler says. "Even though we still have a long way to go before we understand all of chocolate’s effects, for now, there’s little doubt that in moderation and in conjunction with a healthy, balanced diet and exercise we can enjoy -- and even benefit from -- moderate amounts of high-flavonoid dark chocolate."

Engler’s co-author, Marguerite Engler, PhD, RN, presented an abstract of this research at the American Heart Association’s Scientific Sessions in New Orleans in November 2002. Mary Engler and her team also presented the work at the Experimental Biology 2003 meeting in San Diego in April 2003. The abstract was published in The FASEB Journal in conjunction with that meeting.

Other researchers who participated in the study are Amanda Browne, RN, BS, Elisa Chiu, RN, MS, Michele Mietus-Snyder, MD, all from the Department of Physiological Nursing, UCSF School of Nursing; Chung Y. Chen, PhD, Ho-Kyung Kwak, PhD, Paul Milbury, MS, and Jeffrey Blumberg, PhD, FACN, all from the Jean Mayer USDA Human Nutrition Research Center on Aging, Antioxidants Research Laboratory at Tufts University, Boston, MA; Mary J. Malloy, MD, Cardiovascular Research Institute at UCSF, and Steven M. Paul, PhD, Office of Research, UCSF School of Nursing.

Joan Aragone | EurekAlert!
Further information:
http://www.ucsf.edu/

More articles from Studies and Analyses:

nachricht Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland

nachricht Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>