Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
To the Editor: In vitro studies have suggested
that flavonoids may have specific vascular effects, but their mechanism of
action has not been clarified.1 A subclass
of flavonoids—flavan-3-ols and their oligomers (procyanidins)—are
constituents of cocoa beans, which can be detected in human plasma after ingestion
of cocoa.2 In turn, plant extracts rich
in flavan-3-ols can increase the activity of nitric oxide synthase (NOS) in
endothelial cells.3 Nitric oxide is an essential
signaling molecule in vascular physiology. Nitric oxide bioactivity can be
preserved in human plasma in a circulating pool via increases in a number
of nitrosated compounds.4,5 Thus,
it is possible that cocoa rich in flavan-3-ols may lead to improved endothelium-dependent
dilation via an increase of nitric oxide bioactivity.
Heiss C, Dejam A, Kleinbongard P, Schewe T, Sies H, Kelm M. Vascular Effects of Cocoa Rich in Flavan-3-ols. JAMA. 2003;290(8):1030-1031. doi:10.1001/jama.290.8.1030