On the dietary front, several nutrients have been tied to improved resistance to viruses. Taking zinc supplements, for example, has been linked to a reduced rate of respiratory infections and shorter duration of related symptoms. Deficiency in zinc, a mineral found in meat, shellfish, nuts and whole grains, is more prevalent in less developed countries, Fawzi notes, but it can occur in wealthier nations, especially during a time of high unemployment and disruptions to the food supply chain.