Nutrition and Immunity
Good nutrition is a key precondition for effective immune function. There is now robust evidence for the critical contribution of several specific nutrients to the immune response. Inadequacy of these nutrients is relatively common which explains increased vulnerability to respiratory tract infections in children and adults, not least the common infections of nose and throat during the cold season.
Good nutrition is a key precondition for effective immune function. There is now robust evidence for the critical contribution of several specific nutrients to the immune response. Inadequacy of these nutrients is relatively common which explains increased vulnerability to respiratory tract infections in children and adults, not least the common infections of nose and throat during the cold season.
Numerous nutrients are needed for an effective innate and acquired immune response to infection.1 Some of these, including vitamins A and D, selenium, iron, and polyunsaturated fatty acids, play essential roles in the proliferation and maintenance of epithelial cells and white blood cells which are the body’s basic defense mechanisms. These nutrients are found in several good food sources and can be supplemented if need be.
Nutrient deficiencies in vitamin A, vitamin D2, omega-3 fatty acids, iron, copper, and selenium appear to contribute to the development and severity of respiratory tract infections. The COVID-19 pandemic has further highlighted the importance of nutrition. The increased risk of COVID-19 infection and more severe outcomes have become apparent in populations living at high latitudes, such as North and Central European countries, and Canada. Early in the pandemic, people living in the northern half of the United States had 8–10 times the risk of dying from COVID-19 than those in the southern half of the United States. Self-described African Americans were twice as likely to die than light-skinned Americans3, also with a strong latitudinal gradient of the risk. These two observations could point to an important role of vitamin D because both are linked to differences in UV-mediated vitamin D production in the skin.
Links between vitamin D deficiency and increased susceptibility to COVID-19 infection were reported from both observational4 and interventional5 studies, though results varied and appeared to depend on both adequate dosing and early timing.
In the end, avoidance of deficiencies in critical nutrients as well as having a good overall nutritional status and balanced metabolism is the best starting point for a resilient immune system.
References
1 Calder PC. Nutrition, immunity and COVID-19. BMJ Nutr Prev Health. 2020 May 20;3(1):74–92.
2 Lanham-New SA, Webb AR, Cashman KD, Buttriss JL, Fallowfield JL, Masud T, et al. Vitamin D and SARS-CoV-2 virus/COVID-19 disease. BMJ Nutr Prev Health. 2020 May 13;3(1):106–10.
3 Kohlmeier M. Avoidance of vitamin D deficiency to slow the COVID-19 pandemic. BMJ Nutr Prev Health. 2020 May 20;3(1):67–73.
4 Louca P, Murray B, Klaser K, Graham MS, Mazidi M, Leeming ER, et al. Modest effects of dietary supplements during the COVID-19 pandemic: insights from 445 850 users of the COVID-19 Symptom Study app. BMJ Nutr Prev Health. 2021 Apr 19;4(1):149–57.
5 Alcala-Diaz JF, Limia-Perez L, Gomez-Huelgas R, Martin-Escalante MD, CortesRodriguez B, Zambrana-Garcia JL, et al. Calcifediol treatment and hospital mortality due to COVID-19: a cohort study. Nutrients. 2021 May 21;13(6):1760.
