Against the new coronavirus it is important to strictly follow the rules, the hygienic measures and the physical distancing, washing the hands frequently and disinfecting them with solutions that contain at least 60% alcohol. But it is also important to take care of our health and that of our immune system through the diet in order to provide those nutrients capable of fortifying our defenses against external threats. In addition to vitamin D and zinc, two other substances that seem to play a role are vitamin C and quercetin, which, when taken together, work in synergy, enhancing their antiviral effect. This is what emerges from a recent scientific research published in the journal Frontiers in Immunology that summarizes the work of an American team (Biancatelli et al, Front Immunol, 2020).
Vitamin C reduces inflammation and downregulates the cytokine storm. This is noteworthy since, in severe cases of novel coronavirus infection, the cytokine storm causes the greatest danger by inducing an out-of-control immune response. Not only that, vitamin C also has a direct virucidal action and low levels of this vitamin, namely lower than 11 micromol per liter, have been detected in patients suffering from the novel coronavirus, hospitalized and with more complicated clinical courses than those who had normal vitamin C values. As for quercetin, this is an anti-inflammatory, antiviral and immunoprotective substance. Quercetin has been shown to be able to block the entry of the coronavirus into the host cell and its replication, by binding to the proteins found on the surface of the virus. Therefore, as pointed out by the review authors, combining vitamin C and quercetin together would help increase the antiviral action and the support to the immune system. But it would also have another very important effect. In fact, quercetin can undergo oxidation, forming compounds that are not only no longer useful but are also toxic. This double valence, antioxidant and pro-oxidant, of quercetin is called the quercetin paradox. Well, vitamin C, by donating missing electrons to the oxidized quercetin compound, can transform it back into quercetin. Hence the importance of taking a combination of quercetin and vitamin C both for preventive purposes and to treat the initial stages of viral infections. In any case, before starting any treatment with supplements, always consult your doctor to avoid taking excessive amounts of nutrients. Quercetin and vitamin C can in any case also be taken with the diet. Quercetin is contained in capers, onions, shallots, berries, tea, elderberries, apples, grapes and broccoli. Vitamin C is contained in citrus fruits, berries, kiwis, mangoes, broccoli, leafy greens, peppers and tomatoes.