improve smokers' blood vessel health
By Dominique Patton
Flavanols, the natural
chemicals found in chocolate, fruits and tea, can boost the levels of nitric
oxide in the blood of smokers and reverse some of the smoking-related damage to
blood vessels, say German researchers.
Previous research has already shown that flavonols protect blood vessel health
and it is therefore thought that they should benefit the
heart. But the new study, reported in
the 4 October issue of the Journal of the American College of Cardiology
(vol 46, pp1276-1283), is important because it demonstrates these benefits in
smokers, people that have raised risk of heart disease.
blood vessels tend to respond poorly to
changes in blood flow, possibly related to impairments in how nitric oxide sends
signals to the inner lining, the endothelium, of blood vessels.
This impaired endothelial function is a marker for increased risk of
Dr Malte Kelm from the Heinrich-Heine-University in Duesseldorf and his team
recruited 12 healthy smokers in their early 30s for their double-blind,
On the first day they were given either a cocoa drink made by Mars that is
enriched in flavanols or a drink that tasted the same, but contained very low
of flavanols, and then crossed over on the second day.
Circulating nitric oxide levels and blood vessel responses (or the flow-mediated
were measured before drinking the cocoa and again two hours later.
There were significant increases in circulating nitric oxide and flow-mediated
after ingestion of drinks containing 176 to 185 milligrams of flavanols, a dose
exerting maximal effects. These changes correlated with increases in
In addition, the improvements were reversed when the participants were given a
(L-NMMA) that interferes with nitric oxide signaling, thus supporting the idea
the flavanol-rich cocoa drink produced its effects by influencing the nitric
together, these findings support the notion that flavanol-rich foods, including
cocoa products, may help to promote cardiovascular health,"
Dr Kelm said.
The small study needs to be confirmed by further research, however, before
consumers can be advised to consume high amounts of flavanols for heart health.
It is still not known, for example, whether or not the chronic consumption of
flavanol-rich foods can lead to sustained increases in endothelial function, and
the prevention of future cardiovascular events.
Lead author Christian Heiss added that in smokers, it is unlikely that cocoa can
completely attenuate the deleterious effects.
However Mary B. Engler, based at the University of California in San Francisco,
noted that the study has helped to identify the optimal concentrations,
potential mechanisms and the role of biologically active metabolites of the
cocoa flavonoids in the improvement in vascular function in smokers.