Food and Behaviour Research

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Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections

Calder PC, Carr AC, Gombart AF, Eggersdorfer M. (2020) Nutrients 12(4) 1181; 

Web URL: View this and related articles via PubMed here. Free full text of this article is available online


Public health practices including handwashing and vaccinations help reduce the spread and impact of infections. Nevertheless, the global burden of infection is high, and additional measures are necessary. Acute respiratory tract infections, for example, were responsible for approximately 2.38 million deaths worldwide in 2016.

The role nutrition plays in supporting the immune system is well-established. A wealth of mechanistic and clinical data show that vitamins, including vitamins A, B6, B12, C, D, E, and folate; trace elements, including zinc, iron, selenium, magnesium, and copper; and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid play important and complementary roles in supporting the immune system.

Inadequate intake and status of these nutrients are widespread, leading to a decrease in resistance to infections and as a consequence an increase in disease burden. Against this background the following conclusions are made:
(1) supplementation with the above micronutrients and omega-3 fatty acids is a safe, effective, and low-cost strategy to help support optimal immune function;
(2) supplementation above the Recommended Dietary Allowance (RDA), but within recommended upper safety limits, for specific nutrients such as vitamins C and D is warranted; and
(3) public health officials are encouraged to include nutritional strategies in their recommendations to improve public health. 


This open-access article from Professor Philip Calder and colleagues at the University of Southampton explains why nutrition and diet are fundamental to a healthy immune system - and therefore why more and better public health advice on nutrition is essential in combating the current epidemic of the viral infection known as COVID-19.

Given that many key nutrients required for a healthy immune system are NOT provided in sufficient quantities by the diets consumed by many people in developed countries like the UK (including the long-chain omega-3 fatty acids EPA and DHA, vitamins A, B6, B12, C, D, E, and folate; and essential trace minerals including zinc, iron, selenium, magnesium, and copper), the researchers also makes specific recommendations for dietary supplementation to provide the recommended daily intakes (RDA) of these micronutrients.

In the case of Vitamins C and D, they also point out that supplementation of these nutrients at levels well above the basic RDA would be appropriate, as existing evidence shows that these vitamins are particularly important in protecting against severe respiratory viral infections such as COVID-19.

For a summary of this research, see: