Letters Section Editor: Robert M. Golub, MD, Senior Editor.
To the Editor: In their study of cocoa intake and blood pressure, Dr Taubert and colleagues1 concluded that the reduction of diastolic and systolic blood pressure caused by dark chocolate intake was due to increased formation of S-nitrosoglutathione. Many biochemical markers were measured in the study using commercially available assays or reported methods. However, we are not aware of reports of the analytical performance of the liquid chromatography tandem mass spectrometry method used for the measurement of plasma S-nitrosoglutathione. This is potentially an important problem for research involving S-nitrosothiols, for which the reported concentrations in biological fluids has a 3–order magnitude range.2
Tsikas D, Rossi R. Cocoa Intake and Blood Pressure. JAMA. 2007;298(16):1862-1864. doi:10.1001/jama.298.16.1862-b