Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) - a novel coronavirus has rapid spread, and caused community infection around the globe. During the absence of a vaccine, people focused more on an immunity-boosting diet and needed clear knowledge about immunity-boosting foods. However, after the vaccination drive, the importance of food as a natural source of immunomodulation cannot be neglected. So, the purpose of this review was to describe the role of vital nutrient in boosting immune system of body apart from other factors like adequate sleep, exercise, and low stress levels. Macrophages, neutrophils, natural killer cells, dendritic cells, B-cells, and T-cells are the important components having important role in maintaining immunity of the human body. The first four-act as the initial mediator of innate host defense, and the latter two produced antibodies for pathogen destruction. The review investigated vital nutrients like vitamin-C, A, E and D, iron, zinc, folic acid, probiotics, and prebiotics affecting these immune components in some extent. Fruits, vegetables, spices, herbs, seeds, nuts, cereals, millets, and superfoods like chlorella and spirulina are good sources of these nutrients. However, fortified foods, functional foods, encapsulated foods with bioactive compounds and plant-based foods have shown immense potential in boosting immunity against viral infection like COVID-19. Some clinical trials and retrospective cohort study have shown reduction in the severity of COVID-19 patients with relation to plant-based diet, vitamin D and C doses, probiotic, and zinc salts application.
