As the coronavirus spread across the UK, many people became more interested in nutrition and diet in relation to immunity.

Food, nutrients and the immune system

The immune system is a complex network of cells and chemical compounds that help defend the body against infections. Many different nutrients are involved in supporting our immune systems to work normally so that we can deal with infections.1

These include, but are not limited to, vitamins A, B6, B12, C, and D, and folate, selenium and zinc. These immune-supporting nutrients are found in a wide range of foods so having a healthy, varied diet is the best way to get all the nutrients that are important for the immune system. But while it is important for the normal functioning of the immune system to get enough of these nutrients, it doesn’t follow that having more will actually ‘boost’ it; in fact excess of some nutrients can be harmful.


There’s not enough evidence to suggest that dietary supplements can prevent or treat viral infections. There is some evidence that vitamin C may reduce the duration and severity of the common cold, but it’s not clear whether vitamin C would have any effect on COVID-19 symptoms. There’s also been some research into the effect of zinc supplements on the common cold, but more research is needed to determine if they have any clinical benefit, and if so the effective dosage and formulations. Again, we don’t know that supplements would have any benefit against COVID-19.

What about vitamin D?

Public Health England recommends that everyone should consider a daily 10 microgram vitamin D supplement during lockdown, because of reduced sun exposure. This recommendation is not about preventing coronavirus but for maintaining muscle and bone health. There’s currently insufficient evidence on the role of vitamin D and risk of respiratory tract infections.2


1British Nutrition Foundation. Coronavirus outbreak: nutrition and immunity – be careful of myths and false promises. 2020.

2GOV.UK. Insufficient evidence for vitamin D preventing or treating ARTIs. 2020.