How not to catch a bug

You don't have to suffer. You just have to do the right thing.

It’s cold. Summer’s long gone and it’s mean out there. There are viruses circling the wagons, looking for a warm, easy host. One that won’t put up much of a fight. Is that you?

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There are those people who catch everything that’s drifting along on the breeze. Yet there are others who don’t, or who shrug off would-be assailants with ease. What separates these two camps?

Whatever it is, it probably isn’t a face mask.  A January 2023 Cochrane review of all the evidence (Cochrane being the gold standard of reviews) concluded that ‘Wearing masks in the community probably makes little or no difference’ to getting flu or covid-19.

Marvellous. We wore those bacteria-ridden face coverings (and who among us didn’t keep wearing the same old scrap until it become a health hazard?) for no reason at all. We got jabbed, once, twice, thrice, before proceeding to catch the virus and pass it on to anyone with the misfortune to enter our airspace.

You were urged to get the covid jab. Then you were urged to get the flu jab.

At what point were you urged to strengthen your immune system? To arm yourself with the best possible natural defence?

Your immune system is massively underrated. It is the only thing standing between you and death, every second of your life. That’s not me being a drama queen; there’s a lot going on, beneath the surface.

Bacteria are microscopic in size, but a virus is about a thousand times smaller. Unlike bacteria, a virus needs a host, where it can multiply rapidly. And there you are! In they pile, through your mouth, nose, bodily fluids and cuts in the skin.

Once it comes into contact with a cell in your body, the virus attaches itself to the cell membrane and injects its DNA into the cell. The wall is breeched, and the cell dies. The virus is now able to replicate inside the cell — making as many as 10,000 copies of itself that can then travel to other parts of the body, including the lungs. The process is repeated, over and over.

Your immune system responds to an attack from a virus by launching a counterattack. It does this by first raising your body temperature and creating a fever to fight the infection. A fever may be unpleasant, but it a sign that your immune system has responded and is at work.

Part of the prodigious arsenal at the disposal of the immune system are antibodies. Antibodies are proteins made by white blood cells that respond to the attacker, or antigen. The antibody latches on to the virus and disables it. You have millions — billions — of antibodies swimming through your bloodstream all the time, carrying a memory of, and on the lookout for, old diseases they were commissioned to fight in the past.

It can take several days for the immune system to create new antibodies for a new threat.

Even so, there’s no time to idle. While your body is busy in the lab creating the right antibody for the new virus, other elements of the immune system are launching their own attack to limit the spread of the new virus. These elements include cytotoxic T-cells. This T-cell recognises and kills the cells that have become infected with the virus, preventing the virus from spreading any further.

But the cunning virus has developed means of avoiding detection by a cytotoxic T-cell, by camouflaging the surface of the cell it has invaded.

Your immune system, also pretty smart, knows this, so sends out natural killer (NK) cells that specialise in recognizing and killing these camouflaged cells by injecting them with toxic substances. Both NK and cytotoxic T-cells make these toxins, and proteins called perforin drill holes in the cell membrane and allow the toxin to enter the cell and destroy it.

The infected cell isn’t entirely helpless in this battle: it too puts up a fight by producing proteins called interferons that prevent the virus from replicating. While they do that, they signal to other cells nearby to warn them that there is a virus present, so they too can prepare themselves to fight.

All this amazing warfare, while you lie there, inert, sweating, and bingeing on box sets.

And here’s some really good news (or really bad, depending on where you are with your healthy lifestyle resolutions). Your immunity is influenced by external factors, including diet, stress, and environmental chemicals.

Diet is a powerful component of immunity. It works at both ends of the spectrum and can be compromised by both under- and over-nutrition.

Undernutrition ‘severely’ reduces the immune systems response, and nowhere is this more stark than in childhood undernutrition in developing countries, where there is a high mortality rate as children succumb to infection. Even mild forms of undernutrition are related to underlying immunodeficiency.

Overnutrition - that is, excessive calorie intake, on the other hand, can lead to inflammation and poor immunity. Obesity means fewer white blood cells to fight infection. It also means more inflammation, which reduces immunity.

“Obesity, like other states of malnutrition, is known to impair the immune function, altering leucocyte counts as well as cell-mediated immune responses.”

Nothing contributes more to excessive and empty calorie intake than sugar. Sugar negatively impacts the immune system by triggering inflammation and reducing production of phagocytes, white blood cells that are part of the immune system army, and work by ingesting harmful invaders and dead and dying cells.

And nothing has the opposite effect of sugar quite like vitamin D. Without adequate vitamin D, those all-important T cells can’t be activated. T-cells send out alarm signals, calling for the mobilisation of vitamin D. Vitamin D is critical for your first line of defence against invading pathogens. But if you haven’t got any left in your reserves, those T-cells fail to function properly, and you are left exposed and vulnerable.

At this time of year, and without supplements, I wouldn’t much fancy your chances of activating those T cells, whether it be flu or covid, chesty cough, or just a heavy cold. You make vitamin D in the skin in the presence of sunlight, but only during the late spring and summer months, depending on where you live. By October, your liver has run out of reserve. You are entirely dependent on a limited number of dietary sources, and supplements.

Vitamin D is safe and inexpensive. For that reason, scientists now take the view that by taking it, there is nothing to lose, and potentially much to gain.

“…it would seem uncontroversial to enthusiastically promote efforts to achieve reference nutrient intakes of vitamin D, which range from 400 IU/day in the UK to 600–800 IU/day in the USA…. there is nothing to lose from their implementation, and potentially much to gain”.

Many trials have shown that vitamin D supplementation offers protection against acute respiratory tract infections by strengthening mucosal defences. Low vitamin D is associated with increased susceptibility to infectious diseases of the upper respiratory tract.

Good dietary sources

Oily fish, particularly salmon, is the best source.  Salmon is pretty decent, but even then, it has to be wild. Farmed salmon has been found to have only 25% of the vitamin D content of its wild counterpart. Wild salmon contains approximately 400iu of D3 per 3.5oz — a typical serving size.

Eggs are also a good source, with the yolk containing almost all the vitamin D. And there’s a big difference between eggs from hens that are free range, and eggs from indoor-reared hens. Free-range eggs have been found to contain 3–4 times more vitamin D than non-free-range eggs. Whereas free-range egg yolk may average 14.3μg per 100g of vitamin D, yolk from indoor eggs may average as little as 3.8μg vitamin D per 100g.

After eggs, your next best source is meat, including offal. Meats with a high fat content, such as lamb, tend to have the highest amounts of D3. Which is convenient, because vitamin D is fat soluble, which means that you have to eat fat in order to absorb it in the gut.

Dairy is another natural source, though not a great one. Like eggs, the D3 content of dairy can vary according to the animal’s habitat and quality of life — the D3 content of dairy is much affected by outdoor grazing. Even so, unless milk has been fortified, it is not a rich source of vitamin D3, and if it is skimmed it contains undetectable amounts. Butter is an exception to the dairy rule, containing reasonable amounts of D3.

What’s recommended?

There are two types of vitamin D: D2 and D3. The form that humans make and use is vitamin D3. Vitamin D3 is converted to 25(OH)D, the form of vitamin D that circulates in the blood.

It was once thought that there was no difference between D2 (ergocalciferol) and D3 (cholecalciferol) in their ability to improve vitamin D status. However, trials in humans now consistently find that vitamin D3 increases total 25(OH)D concentrations much more than D2.

How much?

Recommended doses vary — 400iu (international units) generally, rising to 600–800iu for the housebound, and 800–1000iu for people aged 70 and above. That’s the minimum requirement – I usually recommend my clients take at least 1,000iu daily, in spray form, during the winter months.

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In truth, most of us are lucky to be here at all. Once, the survival of our species was determined by natural selection, as it is with all other animals in the wild. For virtually the entire history of humanity, beginning with the Palaeolithic era, natural selection meant that our reproductive success was low. The likelihood of a newborn baby growing up to pass on its genes to the next generation was just 30%. Only half of newborns reached the age of 15.

Natural selection is a brutal but effective system, operated throughout the animal and plant kingdoms, that ensures the survival of a strong species at the expense of the weak. However, it no longer applies to humans: we’ve overridden nature.

Today, modern medicine and public health interventions have ‘produced for the first time in human history virtual lack of the operation of natural selection on biological traits of humans.’

Which leads us all to ponder the mysterious and slightly disturbing question of who among us would be in the 30% that would have made it here under our own steam, without modern medicine or public health interventions. My advice is to assume nothing, and put energy into building your own internal medicine cabinet. Vitamin D is a good place to start.