Nutrition and Immunity

Both the constantly active innate immune system and the later acting humoral defenses depend on adequate supplies of vitamins and trace elements. An array of essential micronutrients, specifically omega-3 polyunsaturated fatty acids (PUFAs), the vitamins A, D and E, as well as iron, copper, zinc, and selenium are of critical importance for protection against many contagious diseases, including viral infections of the upper respiratory tract. Balanced, micronutrient-rich food choices are an important foundation for a strong immune system and resilience against disease. A good vitamin D status appears to play a significant role in the protection against the upper respiratory tract infection COVID-19 caused by SARS-CoV-2, particularly at the time of initial exposure to the virus. The likelihood of infection and mortality risk during the first months of the pandemic was closely linked to skin pigmentation and how far north (latitude) the people lived, pointing to a potential role of sunlight (UV-B) exposure and vitamin D status. The excess risk of people with obesity may be explained at least in part by their typically lower vitamin D concentrations in blood. Habitual use of dietary supplements with moderate amounts of vitamin D was associated with slightly reduced disease risk in some studies.