HOW DOES ZINC MODIFY THE COMMON COLD - CLINICAL OBSERVATIONS AND IMPLICATIONS REGARDING MECHANISMS OF ACTION

Clinical studies have shown that ionic zinc (Zn2+) dissolved in the mo uth shortened manifestations of the common cold significantly, by an u nknown mechanism. The observed immediate effect on symptoms is consona nt with osmotic transport of Zn2+, placing a temporary chemical clamp on critical nerves. It is proposed that transient elevation of Zn2+ co ncentration in and around the nasal cavity facilitates Zn2+ complexati on with known intercellular adhesion molecule binding sites on rhinovi rus surfaces which prevents rhinovirus binding to cells and interrupts infection. The crystallographically determined surface of rhinovirus- 14 has been found to contain binding sites for at least 360 Zn2+. Such binding of Zn2+ would be stabilized by numerous histidine, methionine , tyrosine and carboxyl/carboxylate groups known to line the HRV-14 su rface canyons. The resulting blockage of HRV docking with intercellula r adhesion molecule binding sites is proposed to be responsible for th e observed reduction of the duration of colds by statistically signifi cant and clinically meaningful times.