Home is where the immunity is
During the Covid-19 pandemic, there’s talk of ‘boosting’ our immune system. That’s misleading, writes Dr Kate Gregorevic.
Unsurprisingly, various supplement companies and celebrity influencers are using the current global health crisis to sell products they claim ‘‘boost the immune system’’.
When I read anything about ‘‘boosting the immune system’’, I immediately know that the user doesn’t actually know how the immune system works.
To understand why you can’t boost the immune system with juices, supplements, an expensive energy machine, or essential oils, it’s worth understanding a little more about how the immune system actually works.
How does your immune system work?
Our immune system is our defence against threats. This includes injuries, cancer and, of course, infections, like the novel coronavirus that causes Covid-19.
Our immune system is a complex system that includes physical barriers like skin and snot; multiple cell types, like macrophages that ‘‘eat’’ bacteria and lymphocytes that make antibodies; and chemical messengers that act locally and throughout the body. Without a functioning immune system, complex life isn’t possible.
Most of the human coronaviruses are so mild that people usually pay very little attention to them. These are the annoying coughs and colds that rarely slow us down.
But this novel coronavirus is capable of causing a much more severe disease, partly because of the way it activates the immune system.
What happens when your body meets a virus?
When we get a virus, it attaches to receptors in cells in the airways and lets itself inside.
Viruses can’t make copies of themselves, so they hijack other cells to do the work for them, a process that can damage the cells.
A virus doesn’t actually want to make its host too unwell. It needs us alive to keep making more viral particles and ideally well enough to walk around and cough and sneeze on others.
Our immune systems have evolved sophisticated defences against viruses. When a cell is infected, it displays markers on the outside that show that it has foreign genetic material present. This can activate patrolling immune cells, which then kill the infected cell.
The infected cells also release cytokines, chemical messengers that travel throughout the body to ‘‘wake up’’ the immune system, which can lead to spiking a fever or that feeling where you just want to crawl into bed.
No such thing as super-charging immunity
The problem with the idea of ‘‘boosting immunity’’ is that the immune system is regulated through a complex set of ‘‘on’’ and ‘‘off’’ switches. These work through the aforementioned chemical messengers called cytokines, which mobilise the body’s defence mechanisms.
Almost everything we do can influence these cytokines, including exercise, heat, cold, our gut microbiome, and sleep.
That is why eating a balanced diet, regular exercise, and sufficient sleep all play a role in healthy immune function.
However, unless someone has a specific vitamin or mineral deficiency, taking more vitamins than our body needs in a day will not change or ‘‘boost’’ levels of immune activity. At best, our body gets rid of the excess, at worst it can actually be toxic.
Covid-19 and our immune system
Viruses have their own defences and one of them is to suppress our own immune response.
Professor Damian Purcell, a virologist at the Doherty Institute, says that this new coronavirus is particularly good at suppressing our innate immune system, which is our first line of defence.
This allows the virus to hang around longer, while our infected cells keep producing yet more virus while suppressing the immune response.
This explains why people with this infection can spend the first few days with only mild symptoms or none at all.
The time when people become really unwell with Covid-19 is around days 7-10, which is when the body starts producing antibodies. For most people, this will control the disease, but for a small number, Purcell says, this seems to be associated with an overactive immune response (a loss of the normal controlling mechanisms that signal to ‘‘switch’’ the immune system on and off in response to a threat).
When the immune system goes into overdrive, it leads to uncontrolled inflammation, with the lungs hardest hit. Immune cells and fluid then wind up in the air sacs of the lungs, which can cause respiratory failure.
From a doctor’s perspective, the language of ‘‘boosting’’ the immune system becomes particularly ridiculous when you consider that uncontrolled high levels of immune activity can actually cause tissue damage as a result of inflammation.
Over decades, higher levels of systemic inflammation are associated with the development of most chronic diseases, including the build-up of atherosclerotic plaque made up of fat, cholesterol and calcium in the walls of the blood vessels, as well as dementia and diabetes.
When I see ads for supplements and essential oils claiming to boost immunity, I can see the appeal. We all want to do something to make ourselves and those we love safe.
Getting enough sleep and exercise, eating well and maintaining social connections are all excellent for mental and physical wellbeing, and optimising immune function.
However, until there is a vaccine, no amount of vitamins can boost your immune system and protect against Covid-19.
Although we know some groups are more susceptible than others, like older adults and those with pre-existing medical conditions, we don’t know which person with Covid-19 will have mild symptoms and who will end up on a ventilator.
Researchers are working hard to understand the biological mechanisms of this disease and conducting drug trials to find effective treatments.
While we await the development of a vaccine, we do have an entirely natural therapy that is already working: stay home.
● Dr Kate Gregorevic is an Australian clinician and researcher with an interest in understanding the ageing process and helping people make positive changes in their lives to improve longevity.
While we await the development of a vaccine, we do have an entirely natural therapy that is already working: stay home.