The immune system defends the host from many pathogenic microorganisms such as viruses, bacteria, parasites and fungi, including a large number of specific cell types, interrelated molecules, and biological responses. Due to infections, heightened immune system activity is accompanied by expanded metabolic activities, requiring appropriate energy supply, precursors for biosynthesis and regulatory molecules. Numerous vitamins and minerals play a crucial role in supporting body's immunity and fighting against viral infections. Other bioactive compounds like omega-3 fatty acids, probiotics and antioxidants (alpha-lipoic acid, quercetin) are also important in the immune response. COVID-19 may develop mild symptoms to severe damage of the respiratory epithelium followed by a cytokine storm. Many studies show that vitamin C, vitamin D, zinc and selenium are critical in defending against SARS-CoV-2 infection. Intestinal dysbiosis is a feature of many infectious diseases, including COVID-19, so dietary approaches to establishing a healthy microbiota are essential for improving immune function. This paper reviews the data on the roles and potential effectiveness of selected nutraceuticals in the prevention and treatment of COVID-19.