Zinc is known to be important for immune function. It has a role in antibody and white blood cell production and fights infections, while zinc deficiency increases inflammation and decreases the production of antibodies. High-dose zinc has also been found to reduce the duration of symptoms of the common cold. Zinc is currently being investigated for the treatment of patients with COVID-19.
Vitamin D deficiency is common, with lack of sun exposure, older age, corticosteroid use and darker skin associated with lower concentrations of 25-hydroxyvitamin D. This deficiency is associated with a higher incidence of acute respiratory infections. It is also hypothesized that there is a link between seasonal influenza and vitamin D deficiency. Vitamin D supplementation has also been shown to decrease the incidence of acute respiratory infection.
Ascorbic acid, or vitamin C, is an antioxidant, with a number of studies suggesting that vitamin C supplementation impacts the immune system. Additionally, studies in birds have shown that vitamin C might protect against avian coronavirus infection, with human trials finding that vitamin C may decrease susceptibility to viral respiratory infections and pneumonia. New clinical trials are underway in China and the United States to determine if vitamin C might be used as a treatment for COVID-19.
Quercetin is a natural antihistamine and anti-inflammatory plant pigment that boosts your immune system and may work to control viral replication, according to some research.