The world-wide spread of the coronavirus has highlighted, among other things, the importance of maintaining good health and particularly a strong immune system.

Has there ever been a more crucial time in recent history for understanding the proverbial chinks in our armour and how to safeguard against them? This is exactly what understanding your genes is about, being armed with the exact right tools to improve your defences and therefore your overall health. 

Our newsfeeds are being bombarded with information on how to avoid contracting and spreading the virus. This particular virus is passed on through respiratory droplets meaning someone with the virus coughs or sneezes sending infected droplets either onto other surfaces or by touching other surfaces with the hand they have coughed or sneezed into. Practising proper hygiene (hand washing and surface sanitising) is one of the most important things we can do to prevent contamination and spread right now. This is also why it is wise to avoid public places and interaction as much as possible.

Keeping up your body’s natural defences is also vital for resisting and/or reducing the severity of infection should you become exposed. Your immune system is naturally geared to help you fight infection from foreign invading organisms but it can become overwhelmed, especially if it is not given the “ammunition” it needs by way of nutrients and rest. 

The WHO reported last month that about 80% of patients have a mild to moderate experience of coronavirus infection. Those milder cases are because the body’s immune system is able to contain the virus in the upper respiratory tract, preventing it from progressing to the main target, the lungs. Symptoms of coronavirus infection include inflammation, high fever, cough, acute respiratory tract infection and even organ dysfunction in severe cases caused by an over-reaction by the immune system driving inflammation excessively high – this is known as a “cytokine storm”[1] [2].

So, what can you do to bolster your immune system and how do your genes influence which measures need greater attention?

Vitamin C:

An oldie but a goodie, vitamin C has long been associated with immunity but what is it and why? Vitamin C is a water-soluble vitamin and a powerful antioxidant. It supports the immune system in a number of different ways including helping cells put up their defences when an invader is detected, aiding in capturing and breaking down invaders and increasing production of immune cells in response to infection [3]. As a result, vitamin C deficiency results in impaired immunity and higher susceptibility to infections. In turn, infections significantly reduce vitamin C levels because of inflammation and metabolic requirements which deplete vitamin C. 

The body does not produce or store vitamin C so it must be obtained through the diet. Luckily many common foods contain vitamin C: broccoli, kale, citrus, papaya, peppers, sweet potato, strawberries and tomatoes to name a few. 

Supplementation with vitamin C appears to be able to prevent and treat upper respiratory systemic infections which makes it very important for everyone to keep their vitamin C levels high, especially right now. 

Certain genetic variants lead to a high demand on antioxidants (including vitamin C) and therefore increase the need for dietary sources or supplementation. People with variants on the GST family of genes and other genes affecting need for antioxidants may find themselves more susceptible to infection and may need to supplement with higher doses of vitamin C. 

Smokers and people who live in polluted places also require higher amounts of vitamin C.

Vitamin D:

Vitamin D also supports the immune system. So much so that immune cells have their own vitamin D receptors and are capable of making active vitamin D themselves. It is now widely established that vitamin D deficiency is associated with increased incidence of infections [4].

Great, so how do we increase our vitamin D levels then? Well, our skin produces it when exposed to UVB radiation from the sun. This is one of the reasons that infections increase during the winter months when exposure to sunshine is low (or non-existent) and therefore vitamin D levels drop [5]. 

A small amount of vitamin D is also obtained through the diet (fatty fish, beef liver, egg yolks).

Individual need for and ability to use vitamin D in the body varies according to our genes. People with genetic variants on the CYP2R1 and GC genes tend to have lower circulating vitamin D levels (in the blood). People with variants on the VDR gene (which controls vitamin D receptors in the body) show reduced receptivity to circulating vitamin D and may be more susceptible to infection as a result if they do not ensure their vitamin D levels remain normal. 

These genetic variants, which are small changes in a person’s DNA code, are what we test for and report on when assessing a person’s need for specific nutrients. 

Those also at risk of low vitamin D levels who should consider supplementing: people who are frail or housebound and seldom outdoors, those who wear clothing that covers up most of their body when outdoors, people from African or South Asian background with darker skin.

Zinc:

Zinc (Zn) is an essential mineral and antioxidant known to support immune function in humans and to have certain antiviral capabilities. Zn deficiency negatively affects the growth and survival of immune cells, depresses both the innate and adaptive immune systems, and increases inflammation [6] [7].

Low levels of Zn have been shown to correlate with increased oxidative stress and inflammatory cytokines while Zn supplementation in young adults and particularly elderly subjects showed increased antioxidant effects and reduced inflammation [8]. This is of particular importance given that in severe cases the coronavirus induces a cytokine storm. Zn may modulate this overreaction by the immune system. 

Aside from a diet that does not provide adequate zn, there are certain genetic variants that also predispose a person to low levels. People with variants on SLC30A8, a zn transporter, and TNF-a, a gene involved in inflammation, should be mindful of increasing zn-rich foods or should consider supplementing. 

Zn lozenges are a handy way to keep your levels up and also protect your upper respiratory tract. 

Other factors:

There are many other factors that play a role in protecting your immune system including managing stress, quality sleep, mild exercise and a nutrient-rich diet. At this time it is important not to get sucked into the hype and negativity. Try to view self-isolation / quarantine as a time to catch up on rest, read the books you never get around to reading, catch up on series, do gentle exercise and connect with loved ones over video call. 

Lastly, something to be aware of is that viruses tend to have a “sweet spot” temperature range in which they replicate. Above or below this and they become inactive. The “sweet spot” for the coronavirus is between 22-25˚C [9]. This may be one of the reasons that certain counties and regions seem not to have been as badly affected as others.  Applying this principal to food, it’s best to stick to cooked food at the moment.

Wherever you are in the world right now, I wish you good health! 

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