Sunday, 10 May 2020

COVID19 - can Zinc help?

They answer is of course a big yes. But does that mean supplements might help to improve the outcome from COVID19? This needs a more detailed answer, so let's have a look at Zinc....

While our metabolism is like a giant three dimensional jigsaw of many different essential component pieces, of which Zinc is just one, it has a particular and critical role in our relationships with viruses and bacteria and also regulates the inflammatory response. Zinc does therefore have an important role in our individual responses to any infection, including COVID19. 

Indeed, Zinc has played a big part in human history, its alloy with copper making brass and is the fourth most common metal in use in modern age. When a lorry driver, I used to deliver it around the country as ductwork and sheeting. As a metal, it is rather attractive; that it also has a crucial role in our metabolism hints at the incredible complexity of nature. It is widespread in our environment, soils and food. 

I first became interested when I read that Zinc supplementation has been shown to be of potential benefit for people with MS suffering from depression

So is our intake of Zinc a problem that need solving?

What does Zinc do?


Life without Zinc is simply not possible. It speeds up and indeed is absolutely required for many important chemical reactions taking place inside every cell. It has an important role in DNA metabolism and is present in many proteins, helping them fold into the correct shapes with wonderful "Zinc Fingers"

More importantly here, it has important roles in the synthesis and regulation of white cells, the workers of our immune system and so has many roles in protecting us from infections. Good stuff, this zinc!

There are 2-4 grammes of Zinc in the average adult body and we need about 10mg a day in our diet. There is a little stored in the bones and liver though these are rapidly used up when unwell. 
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What about Zinc and COVID19?


In the lab at least Zinc exhibits antiviral activity through inhibition of the chemical tools needed by the coronavirus to multiply within our cells. In other words, Zinc really might put a spanner in COVID's reproductive works, but there is more; a recent study has taken a closer look, and finds that:

"In view of recent data on clinical course of the disease, it appears that adequate Zn status may possess protective effect as adjuvant [add-on] therapy of COVID‑19 through reducing lung inflammation, improvement of mucociliary clearance, [helping clear the lungs] prevention of ventilator‑induced lung injury, modulation of antibacterial and antiviral immunity especially in elderly. Further clinical and experimental studies are strongly required to elucidate the potential role of Zn deficiency in COVID‑19 susceptibility, as well as effects of Zn supplementation, and the underlying mechanisms."

[my clarifications in brackets]

In other words Zinc helps us defeat COVID at just about every stage of the infection:
  • It inhibits COVID reproduction
  • Reduces the activity of COVID'S target in the cell membrane, the ACE2 receptor. 
  • Helps us to cough up phlegm
  • Clobbers the virus directly
  • Regulates the critical (and sometimes out of control) inflammatory response
  • Helps fight the bacterial pneumonia which can follow COVID
  • It can even make ventilation, if needed, less traumatic.

For the readers with an interest in cellular biology, the diagram below shows how it exerts its influence; for those for whom it is baffling, it's enough to know that Zinc (Zn) plays a role in every aspect of our defence against COVID. 





The  authors conclude:

"Although the therapeutic effects of Zn are considered as inconsistent, the existing evidence‑based data indicate efficiency of Zn supplementation and improvement of Zn status in prevention of pneumonia and its complications due to anti‑inflammatory effect of zinc."

The authors also suggest that lack of Zinc might be implicated in the problem of Russian children who seem to be getting more COVID linked pneumonia than seen elsewhere. This is likely to be a particular problem related to food issues in Russia, more so since the collapse of Communism, but it is clearly hints that it is important for us all to be getting enough Zinc.

In other words Zinc has a definite role. Interesting...

Zinc deficiency


Two billion people are not getting enough ZInc in the diet. Its lack is contributing to the deaths of 800,000 people around the world each year. This is a terrible inditement of the quality of global food supply as well is its absolute lack for so many. Its deficiency is thought to be responsible for significant proportion of the stunting of child growth and diarrhoea diseases in Sub-Saharan Africa and Asia. No doubt it will worsen the impact of COVID19 on these Zinc deficient populations.

It is also more likely to be deficient in the elderly and there has long been concerns that its deficiency might be more common than we think.

Elsewhere it has been estimated that 17.3% of the worlds population have inadequate zinc intakes, with the highest estimates in Africa (23.9%) and Asia (19.4%). The picture below shows the sad (non-COVID19) effects on those as particular risk of deficiency:

http://www.karger.com/WebMaterial/ShowPic/130989



In the USA only about 40% of the population are getting enough zinc in the diet, and this is worse in the elderly and in Hispanics. Supplementing with Zinc for residents of US nursing homes reduced the incidence of pneumonia by 50% . This suggests that the frail and elderly are also are at risk. Inactivity means you need to eat less food, less food means less zinc in your diet. 


Are you getting enough?


The answer is likely to be YES, but with some big if's. The US Recommended Daily Allowance for Zinc is 8mg a day for women and 11 for men, more if pregnant or breastfeeding. Vegetarians are likely to need as much as 50% more as plant based Zinc is less well absorbed, though a well balanced vegetarian diet is likely to provide enough and there seems no disadvantage to vegetarians in terms of health outcomes. 

Zinc is not stored in any significant amount in the body in the long terms and so we need an adequate and regular intake from our diet.

One fundamental problem is that levels of minerals in the soil have been declining with time due to intensive modern faming methods. Half the words cereal crops are zinc deficient. This means that intake of Zinc, and other micro-nutrients are declining in our food, and by implication declining in our bodies.  

Too many of the worlds population rely on the vast monocultures of cereals, rice, corn and soya for nutrition, and suffer due to the resultant lack of variety and quality of the diet. It is these areas where Zinc deficiency is predominant. 

Zinc absorption in the diet can be inhibited by phytates common in many cereals and legumes, so unbalanced diets could be leading to deficiency even in populations who, in terms of calories, appear well fed. On a positive note, its absorption can also be enhanced by high protein meals. To complicate matters further, phytates also have positive health effects, so clearly it is all about getting the right balance.

Yet that supplementation can make a difference to children in Russia with COVID, for those with diarrhoea around the world, for the pneumonia-prone elderly in American nursing homes and that it and shortens the duration of colds in the west might suggest that some of us at least, are not getting, or absorbing enough.

There are also difficulties with diagnosing lack of zinc in the diet blood by doing simple blood tests as results can be deceptively normal until our limited stores are used by by infection or other challenges are used up. So approaching your GP for blood tests is not useful.

I can't help join some other obvious dots, for example; a poor diet is associated with depression, zinc supplements seems to improve depression - so zinc in likely to be deficient in poor diets. Not great science; because A=B, and B=C, doesn't always mean that A=C. 

And as usual, we need more trials, but as so often when the science is uncertain, the question is what to do now?

How to get enough Zinc


Zinc is common in all sorts of foods. There is lots of it in meat, albeit declining, seafoods too are a common source, though again quality varies and consumption of sea food has its issues of contamination and sustainability.  For a useful factsheet click here.

Non-meat sources of zinc include legumes, tofu, nuts and seeds, though as I mentioned above, the phytates in legumes can inhibit its absorption.  Fermentation and soaking are likely to help. Real leavened bread is better than unleavened crackers and biscuits too. 

Another problem is our cultural understanding of the importance of food quality and its cooking. From my perspective, this is now a major public health issue. Understanding what constitutes a well prepared, properly cooked, well balanced meal is not being fostered by our educational system and leaves chunks of the population poorly nourished and vulnerable to illness and COVID. 

The "Great British Bake-Off" culture does not help either - its sugary over-produced outcomes are part of the our obesity prone society.

Exercise can help too. The more active you are, the more you need to eat and the more likely you therefore are to be getting enough zinc in the diet. Extreme exercise though might also increase its requirements. The dietary requirement of athletes are more exacting

Despite all this complexity, in essence the greater the variety and the quality of your food, the less unlikely your are to have a problem. However, if you don't (or can't) eat a balanced diet, or you drink too much alcohol, there might be a problem. Those who don't eat meat have to take a bit more care, though should get enough from legumes tofu, nuts and seeds. 

Supplements to the rescue??


Taking supplements might seem a panacea, but are things ever this simple? There are potential pitfalls too. 

For instance copper (another vital micronutrient) and zinc compete for absorption sites in the gut, so taking too much zinc might lead to too little copper. It's a bit of a minefield and each of us will have to make our own decisions.  

As ever, the inverse care law applies: those who eat the worst diets are the ones least likely to be taking supplements. They are also the ones most likely to suffer severe COVID symptoms and complications.

Given all this, what I will personally do is to have some Zinc tablets in my admittedly small supplement store. At the first hint of symptoms, I will take 50mg a day until better. I hope that will keep my short term and naturally limited stores topped up, and that Zinc will be able to perform its functions inside, as I said at the beginning, every cell in my body and in my immune cells in particular. 

Many on line suggest taking Zinc lozenges as the anti viral effect might maximised in the pharynx, but experts disagree

It is easy to buy supplements offering 50mg of Zinc a day, but beware, this is five times our normal daily requirement. 

If you do want to supplement in the longer term, 5-10mg daily should be enough.

I shall keep an eye out for relevant clinical trials and update as they are published.

The last word...


Zinc has an important role in immunity and fighting viral infections and the bacterial complications they can cause. This is very relevant to COVID. There is also evidence that it can inhibit COVID at various stages of its life cycle so it is important to ensure we are getting enough in our diet.  Many people don't. 

In summary:

  • An adequate intake of Zinc from our food is always the safest and healthiest way to ensure we get what we need.
  • Taking Zinc supplements can be effective in malnutrition, or to counter a low quality or unbalanced diet or where there are problems with its absorption. They might also have a role to play in people with mental health problems.
  • It might be reasonable to take zinc during the COVID19 illness while awaiting evidence from clinical trials.
  • For any of us, this is a time to get ready for COVID and the importance of a varied, fresh, organic diet comprising a wide variety of foods grown or grazed on healthy soil and pasture is a crucial part in preparing ourselves.  
  • As a society we also need to have a good hard look at what is happening to our sources of zinc,  and how we are treating that ultimate giver, or taker away of life and health - our soil.






















2 comments:

  1. Brilliant! Thanks so much for pulling together all this relevant info - it makes such a difference to have a trusted source to turn to!

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    1. Thanks for the encouragement. COVID is magnifying the benefits of good health as well as the problems of our western lifestyle and social inequality. You can now subscribe if you wish.

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