8. Conclusions
A well-functioning immune system is important to help reduce the risk of infections, including LRTIs. Currently published data confirmed the well-established role of micronutrients in supporting the immune system. The in vitro and observational studies, and clinical trials, reported in this review show the important role of vitamins A, C, and D, omega 3 fatty acids, and zinc in modulating the immune response. Vitamins and other micronutrients are understood to work together to support an effective immune system, based on a variety of mechanistic and clinical data. However, further studies are needed to evaluate nutrients’ synergistic effects in the immune response against viral infetions. Supplementation with vitamins, omega 3 fatty acids, and zinc appears to be a safe and low-cost way to support optimal function of the immune system, with the potential to reduce the risk and consequences of infection, including viral respiratory infections. Supplementation should be in addition to a healthy diet and fall within recommended upper safety limits set by scientific expert bodies. Therefore, implementing an optimal nutrition, with micronutrients and omega-3 fatty acids supplementation, might be a cost-effective, underestimated strategy to help reduce the burden of infectious diseases worldwide, including COVID-19. Nevertheless, it is important to recognize that nutritional supplementation will not necessarily prevent infections, or cure the disease, but may help decrease symptoms and facilitate recovery.