SARS-CoV-2 is a relatively new coronavirus that emerged in December 2019 in Wuhan, China. Hence, there are no long-term RCTs available investigating the effects of micronutrients to prevent and treat SARS-CoV-2.
However, there are a lot of hypotheses[1][2][3] based on in vitro data and/or study results from different viral infections outlining the potential mechanisms of micronutrients in COVID-19 and often recommend supplementation, especially for older people and people with deficiencies. In these studies, the authors often claim that the protective effects of micronutrients could be used for COVID-19. However, extrapolating from colds to COVID-19 is speculative and potentially dangerous. A position statement by the International Society For Immunonutrition also recommends increasing the intake of micronutrients (vitamin C, vitamin E, vitamin D, and zinc). However, they make a crucial distinction and disclaimer, by stating, “There is no specific evidence these nutritional measures can help protect against or even lessen the effects of COVID-19 infection.”
In summary, it’s clear that a diverse and well-balanced diet covering all essential micronutrients in adequate amounts (but not exceeding RDAs) supports and strengthens the immune system. Whether this is helpful for preventing and treating SARS-CoV-2 remains to be researched in RCTs.