Within a very short space of time, Coronavirus has stormed around the world, leaving many worried about the future, their health, and the health of their loved ones. There’s certainly a lot of information floating around the internet and not all of it is useful. It is important to use factual knowledge to support our actions in preventing the spread of the virus; while regularly upgraded and refined as more is learned in the face of continuing spread, there are inferences we can draw from our current pool of data which may help in the meantime. Whilst the science of coronavirus is still in its infancy, this article provides an overview of the virus and scientifically supported recommendations to boost immune function. 

SARS-CoV-2 is the current strain of coronavirus, whilst coronavirus disease 2019 (or COVID-19) is the name of the disease people develop from this particular strain. Upon infection, symptoms can develop anywhere between 2-14 days with the three most common symptoms including fever, cough and shortness of breath, similar to that of flu. Whilst it is likely that symptoms will be mild, for some it can develop and become severe, as seen in those developing acute respiratory distress or pneumonia. Those with current health conditions including diabetes, cardiovascular or respiratory disease, or hypertension may experience more severe symptoms.  

Currently, prevention of the spread of coronavirus is paramount. The World Health Organisation (WHO) recommends avoiding infection by regularly and thoroughly washing your hands with soap; avoiding touching your eyes, nose and mouth which may provide an entry point into the body for the virus; maintaining distance from those coughing and sneezing; and coughing or sneezing into a tissue, or your elbow crease. Whilst masks are often used to prevent contraction of coronavirus, they are not recommended for providing protection to the general public. Mask use is better suited to those who are infected, wearing them to prevent the spread of the disease to others, and for health care workers .

The risk of developing severe symptoms of coronavirus increases when the immune system is not functioning optimally. Therefore, increasing intake of nutrients that play a role in supporting immune function may be protective. . 

Vitamin A is important for the development of the immune system and supports the health of moist mucous membranes lining the throat and lungs, the areas most likely to be affected by coronavirus. Vitamin A supplementation reduced the duration of fever and cough in children with pneumonia. (1) Increase dietary intake of vitamin A-rich foods from sweet potato and carrots (which last for an extended period of time should you require self-isolation) which can be added to soups and stews. Dark green leafy vegetables, eggs, dairy products and salmon also provide a source of vitamin A.

Vitamin C levels are 10 times higher in the immune-supporting white blood cell fraction of blood than in the plasma fraction, playing several roles in immune functioning. With its antioxidant properties, vitamin C provides protection to cells from the increased free radical production and subsequent oxidative stress associated with viral infections. (2) Vitamin C is also required to clear away toxic cells, protecting tissue from damage. (3) In the event of pneumonia, vitamin C levels may be depleted which, as a consequence, may reduce circulating glutathione, an important antioxidant required for modulation of the immune system. (4) 

Consider stocking up on citrus fruit and purchasing frozen fruits (berries, papaya, pineapple) which have an extended shelf-life, useful in the event of self-isolation. Other vitamin C-rich foods include peppers, kiwi and cruciferous vegetables.

We recommend: Ester-C which provides a 1000mg dose of vitamin C, proven to deliver higher amounts into cells, with levels maintained for 24-hours with a single dose. 

Vitamin D is important for immune function and may play a role in the inhibition of viral infections. (5) As vitamin D is produced in the skin when exposed to UV light, it is important to supplement with vitamin D from September to March (northern hemisphere) when the UV levels are not considered strong enough to support vitamin D production in the body. 

Whilst vitamin D can be consumed in the diet, guidelines on oily fish intake make it difficult to consume an adequate amount of vitamin D in the diet. Mushrooms are the only plant-based source of vitamin D but are not able to provide sufficient amounts to meet the recommended daily intake. If you have not been supplementing with vitamin D throughout winter, you may wish to seek the advice of a nutritionist regarding an appropriate supplement dosage to increase levels. 

We recommend: Pure & Essential Daily Vitamin D3 2000IU or Pure & Essential Vegan Vitamin D3 1000IU which both provide the most biologically active form of vitamin D that is easily absorbed by the body and taken up into the bloodstream 

Zinc helps with regulating the immune response, with research suggesting that zinc deficiency may be a risk factor for immune deficiency and pneumonia in the elderly. (6) Whilst zinc can be consumed in the diet (grass-fed beef, lamb, sesame and pumpkin seeds, chickpeas, lentils, cashews, spinach, asparagus and mushrooms), phytates (a compound present in grains and legumes) may bind zinc, preventing its absorption. Daily supplementation with 25mg zinc, the upper limit for zinc supplementation in adults, may be beneficial to those with low zinc stores.  

In a study on older adults (56-68 years old) in ICU with systemic inflammatory response syndrome, sepsis, severe sepsis or septic shock, daily supplementation of >500mcg selenium had a positive and statistically significant effect on mortality rate. (7) Selenium is an important antioxidant found in seafood, shellfish, poultry, tofu, eggs and brown rice. With the safe upper limit for selenium set at 300mcg, it is not recommended to exceed this without the support of a healthcare practitioner.

We recommend: Pure & Essential Advanced Multivitamin & Minerals which contains vitamins A, C & D, zinc and selenium, in their most bioavailable forms and suitable for plant-based diets, to support immune function

Probiotics support the microbial population in the gut, with supplementation providing immune-boosting benefits and improving outcomes from respiratory infections. (10) The outcome is often strain-specific, with research showing promise for Lactobacillus and Bifidobacterium strains in providing protection to the lungs from viral infections. (10, 11) 

With an estimated 70% of immune cells found in the gut, consider reducing your consumption of foods that cause digestive problems for you. Whilst the health of the gut can be supported in many ways (too many to cover in this article), consider feeding your gut bacteria with fermented foods, such as sauerkraut, miso and kefir, which may have beneficial effects. If you regularly experience digestive problems, this 3-part article series provides symptom-specific advice.

Media-circulated information suggests that garlic will not provide protection from coronavirus. However, garlic has demonstrated antiviral properties and studies support the idea that garlic may be able to provide protection against the influenza B virus and the common cold. (12) Upping your garlic consumption, therefore, certainly won’t do any harm to your health; in fact, you will gain from its beneficial effects on general health. 

Whilst the above nutrients can boost the immune system, also consider ways to reduce the immune burden so that immune function isn’t depleted should infection occur. For example, hyperglycaemia can reduce immune function and increase virulence which may explain why those with diabetes are six times more likely to experience complications from influenza and why diabetes is a risk factor for mortality in coronavirus disease. (13) Consider swapping (and reducing) foods with a high glycaemic index for alternatives with a lower glycaemic index; for example, swap a slice of white toast for a wholemeal seeded bread with avocado; snack on berries rather than sweets; and an oatcake with nut butter rather than a slice of cake. Increasing your vegetable intake with meals can also reduce the glycaemic index of your meal; consider adding a side salad or an extra portion of vegetables.

Psychological stress may negatively alter immune function, increasing the risk for respiratory illness. (14) Whilst stress release differs for everyone, consider increasing activities that bring you joy to balance out stressful times.

Similarly, sleep deprivation can increase susceptibility to infection, with sleep providing a regulatory effect on the immune system. (15) If you are not achieving a minimum of 7 hours of sleep each night, consider ways you can support an earlier bed-time to boost immune function.  

Finally, alcohol is another immune dysregulator. (16) It may be sensible to reduce your alcohol intake at this time or consider other activities during social distancing: a walk in nature, an online yoga class or a bike ride perhaps. Engaging in exercise, including those mentioned, can have a positive effect on decreasing your perception of stress and regulating the immune system. (17, 18)

If you suspect coronavirus, check gov.uk for the latest advice on where to seek support. The information in this article is provided to educate readers to the multi-factorial role of the immune system, and how nutrition may play a role. Whilst so much information may seem overwhelming, especially to those caring for elderly relatives or with underlying health concerns, making one change may benefit your immune health: going to bed earlier, swapping your afternoon treat for a handful of berries, or using the lighter nights as an opportunity to exercise outdoors. Perhaps this article will provide you with focus points that you can improve upon with the support of a nutritionist over a longer period of time, to help boost your immune system long after this coronavirus has passed and before we are faced with another viral epidemic. 

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