Can a Moscow Mule reduce the chance of becoming infected by the coronavirus? That’s just one of the many unusual questions that has come my way as a panicked population clutches at every possible straw. There’s no worry about being kicked by this mule, not in the traditional sense anyway. That’s because this “mule” is a cocktail made by mixing vodka, ginger beer, lime juice and ice cubes that is traditionally served in a copper mug, probably to keep the beverage cold longer. Why “Moscow Mule?” Nobody really seems to know, but the conjecture is that vodka is associated with Moscow and that the drink gives a kick like a mule.
So, can this mule strike a blow to the coronavirus? Not likely. But as it is so often the case for a seemingly outlandish notion, there is a smidgen of science to be found. In this instance, it has to do with the copper mug and the possibility of small amounts of copper dissolving in the beverage and exerting an antiviral effect. Both elemental copper and compounds of copper can exhibit toxicity towards various forms of life. Ancient Egyptians were aware of the antimicrobial effects of copper long before the discovery of microbes. The “Smith Papyrus,” an ancient medical text written over 4000 years ago, describes the addition of copper to drinking water to purify it. That was likely a chance discovery upon noting that water stored in copper vessels was less likely to cause diarrhea. The sea-faring Phoenicians recorded the use of bronze shavings to prevent battle wounds from being infected. Bronze is an alloy of copper and tin.
During the early days of large sailing vessels, ships' bottoms commonly became encrusted with all sorts of foreign materials, particularly barnacles, a type of crustacean. This was a problem because the resulting drag would slow the ships down. When copper sheeting became available in the late 18th century, ship makers began to cover wooden hulls, hoping that barnacles would not stick to the smooth surface. They didn't. But not because they couldn't get a foothold. This became clear when iron hulls were introduced. These had the same encrustation problems as wooden hulls in spite of having a smooth surface. It was the toxicity of copper that did the barnacles in. If copper doses are large enough, people can suffer the same fate. That was clearly demonstrated by Pierre-Desire Moreau, a herbalist in Paris in the 1800s. Authorities became suspicious when his second wife died after persistent vomiting, exactly the same symptoms that wife number one had exhibited before her death. An investigation revealed large amounts of copper in her body. The first wife was exhumed, and copper was found in her body as well. Both had been poisoned with copper sulfate. Moreau defended himself by saying that he had been unhappy and just lost his head. The judges were unimpressed. On October 14, 1874, he really did lose his head on the guillotine.
Can copper now keep us from losing our head over the coronavirus situation? There is evidence from a study in the New England Journal of Medicine that the virus is inactivated in just a few hours on a copper surface. That comes as no great surprise because it is known that when surfaces on items such as bed railings, intravenous poles, trays, and doorknobs in hospitals are coated with copper alloys, the rate of infections decreases. Although copper is expensive, in the long run, it can save on hospitalization expenses.
Copper compounds such as copper oxide can also be infused into fabrics where they can act as disinfectants. Several Israeli companies are now producing masks embedded with nanoparticles of copper compounds that inactivate coronaviruses. But while copper in a mask may prevent the virus from sneaking through, the ingestion of copper, as in drinking from a copper mug is not going to have any effect on viruses in the mucous membranes of the respiratory tract. Luckily, though, you don’t have to worry about being poisoned by a Moscow Mule since the amount of copper leached out from a mug is way too little to cause any toxicity. Indeed, quite the opposite. Copper is an essential nutrient for the body, incorporated into a number of key enzymes. So, go ahead and enjoy the kick of a Moscow Mule but don’t expect it to protect you from any viral disease. And needless to say, copper bracelets will not chase any virus from the hands. Or arthritis from your joints.