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Nutritional help to fight viruses

Optimising your immune potential

Nutrient deficiency is the most frequent cause of a depressed immune system and an overwhelming number of studies have lead to the conclusion that any nutrient deficiency can profoundly impair the immune system. Having said that there are certain nutrients that seem particularly important for immune health; particularly when fighting a virus, so I have written a short summary about each of those below.

Vitamin A

It is widely recognised that children with low vitamin A status are more susceptible to viral infections including measles and respiratory syncytial virus (RSV); and a study looking at the effects of supplementing  vitamin A in patients with the norovirus, demonstrated that it had a positive antiviral effect. The recommended supplementation dose is 1,000 mcg to 3,000 mcg of retinol a day and there are several companies selling it online as a liquid which is easy to take and absorb.

Please note that women who may be pregnant should not take vitamin A supplements.

Vitamin C

Vitamin C has been shown to be antibacterial and antiviral but it’s main effect in the body is to improve the health of the immune system. Many effects have been demonstrated including increasing levels of interferon, a chemical that fights viral infections and cancer.  When taking it as a supplement  to fight an infection; take 2 -3 g of vitamin C ascorbate each day. Ideally, this should be spread over the day and taken as 500mg every 2 -3 hours. If you develop diarrhoea with this amount reduce it until the diarrhoea has gone. Liposomal vitamin C is an alternative supplement and claims to have higher absorption rates.


Many studies have demonstrated the benefits of zinc supplementation to support the recovery from an infectious disease including acute lower respiratory tract infections. In a recent review that looked at 6 different studies of more than 2000 patients with severe pneumonia; scientists concluded that zinc supplementation is effective at reducing mortality in these patients with this particular condition.

When supplementing zinc it is best absorbed on an empty stomach. When choosing a supplement an amino acid chelate or zinc citrate or zinc picolinate are better absorbed than zinc sulphate or zinc oxide. A recommended dose is 15 – 20mg daily.


Vitamin D

There has been a wealth of studies published in the last decade showing a positive role for vitamin D in our immune system. One large review study, of particular interest at the moment, concluded that vitamin D supplementation could offer protection against acute respiratory tract infections; with patients who were the most deficient in the vitamin, benefiting the most.

Ideally blood levels of vitamin D should be tested first before supplementing but as a general guideline most people can safely supplement with 1000 iu a day during  the Autumn, Winter and Spring  when day light hours are shorter.


Lastly, selenium plays a vital role in the health of our immune system and there is concern that levels in food have fallen since the introduction of modern farming techniques. Selenium deficiency is common amongst immunocompromised patients and may explain their increased vulnerability to bacterial and viral infections.

When choosing a supplement Selenomethionine or Selenocysteine are the best forms of

selenium. The supplementary range is 25 -150ug a day.

NB: Please note that the above advice is meant to supplement and not replace the current

government guidelines about the Coronavirus


New Optimum Nutrition Bible by Patrick Holford 2004

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