When it comes to the immune system, many of us seem to adhere to preconceived notions on how to 'boost' one's immunity - taking vitamin C supplements, not smoking, eating your five-a-day, or downing an "immune-boosting" shot of ginger and turmeric.
But how does the immune system actually work, and what is the secret to developing good immunity?
Immunity and the immune system have become trending topics throughout the pandemic, with people across the world eager to boost their body's defences against the various strains of COVID-19. While being vaccinated is the best way to protect yourself against the virus, there are other things you can do to support your immune system and keep it fighting fit.
In a nutshell, maintaining a healthy and strong immune system is imperative to warding off any viruses or infections, be it coronavirus or otherwise.
The immune system is a complex network of cells, tissues and organs, as well as the substances they produce. The immune system includes white blood cells and organs and tissues of the lymph system, such as the thymus, spleen, tonsils, lymph nodes, lymph vessels and bone marrow.
This network works in tandem throughout the body to fight off pathogens, such as viruses that cause infection and disease. There are two connected wings of the immune system: the innate wing and the adaptive wing.
The innate, or general immune system is essential as it drives nonspecific and immediate immune defences when the body is challenged.
According to the US National Center for Biotechnology Information (NCBI), the innate immune system is the body's first line of defence against germs entering the body. It responds in the same way to all germs and foreign substances, which is why it is referred to as the 'nonspecific' immune system. It acts incredibly quickly: for instance, it ensures bacteria that have entered the skin through a small wound are detected and destroyed within a few hours. However, the innate immune system has only limited power to stop the spread of germs.
This is where the adaptive immune system comes into play. The adaptive immune system takes over if the innate immune system is unable to destroy the germs. It specifically targets the type of germ that is causing the infection, but to do that, it first needs to identify the germ. This means it's slower to respond than the innate immune system, but when it does, it's more accurate.
According to the NCBI, the adaptive immune system also has the advantage of being able to 'remember' germs, so the next time a known germ is encountered, the adaptive wing can respond faster and react immediately to the invasion. This memory is also the reason why there are some illnesses you can only contract once in a lifetime, because afterwards, your body becomes 'immune' to the virus.
While it's easy to toss back a ginger shot and call it a day, improving one's immunity is down to a series of choices, rather than quick fixes. Maintaining healthy immune function cannot be achieved by scoffing fast food every day, "balanced" by a probiotic, Berocca and lemon water. It's built through a healthy lifestyle.
To help, Gill Webster, the chief scientist and immunologist at NatureBee, shared with Newshub 10 tips for supporting the body's innate antiviral defences.
"Our day-to-day living and immune resilience depends foremost on the innate wing of the immune system," Webster said.
"There are many ways to keep our innate immune system in good working order. These include good quality daily micro-nutrition and also lifestyle manoeuvres that altogether enable the immune system to remain fighting fit, ensuring it is able to 'pounce' when challenged."
10 tips on how to support the innate antiviral defences:
Get adequate sleep
"The body repairs itself and the immune system replenishes during sleep, which is when we are most at rest. The power of sleep must not be underestimated," Webster said.
"Stress induces a hormone called cortisol, which can stress the immune system and reduce its ability to defend the body."
Develop or maintain an exercise routine
"It is well established that exercise is important for immune function. Exercise increases blood and lymph flow as your muscles contract, and also increases the circulation of immune cells," Webster explained.
"Exercises which increase breathing help expel foreign particles and pathogens that may be residing in the airways."
Minimise alcohol consumption
"Alcohol can suppress your immune system, making you more vulnerable to infections caused by bacteria and viruses. Alcohol is known to disrupt the function of the natural cells in the upper airways that help expel viruses and other pathogens."
"Recent studies are highlighting that vaping can damage vital immune system cells and may be more harmful than previously thought," Webster said.
"Some studies are indicating that vaping increases susceptibility to COVID-19 infection. Smoking cigarettes does the same."
A preliminary 2019 study based in the US, Association Between Youth Smoking, Electronic Cigarette Use, and COVID-19, aimed to assess whether vaping and e-cigarette use among young people was associated with COVID-19 symptoms, testing and diagnosis. The study found that youth who used e-cigarettes were five times more likely to contract COVID-19, while youth who smoked both e-cigarettes and traditional cigarettes were seven times more likely to test positive.
Additionally, e-cigarettes expose a person to nicotine and other harmful chemicals which directly impact the function of the lungs, which might increase the risk of infection or developing a more serious case of COVID-19. According to the US Centers for Disease Control and Prevention (CDC), current smokers and people with a history of smoking may be at a higher risk of developing a severe case of COVID-19, and like other respiratory illnesses, COVID-19 can also cause lasting lung damage.
Maintain or develop good gut health
"The gut is the major conductor of the body's innate immune system. Gut health depends on healthy gut bacteria (called the gut microbiome).
"The best way to promote good gut health is to take multispecies probiotics in a formulated product, or include naturally fermented foods in the diet (such as apple cider vinegar, kimchi, miso or cultured milk/yoghurt foods)."
Ensure adequate daily intake of dietary fibres
"Dietary fibre is the essential food for our gut bacteria, which they metabolise for their own survival, and also release chemicals from their metabolism into our bodies that are immune-protective," Webster explained.
"Different healthy bacteria have different preferences for the fibre that they can metabolise the best, so variety is the spice of their life."
Pay attention to zinc intake
"Zinc is known to play an essential role in the immune system, and zinc deficiency is linked to increased susceptibility to infection.
"There are a variety of common foods that contain meaningful amounts of zinc, such as seeds, whole grains, legumes (such as lentils and chickpeas), dairy foods and eggs."
Pay attention to selenium
"Dietary selenium is crucial for many immune cell functions. In New Zealand there is a lack of dietary selenium in the New Zealand food chain, if the soil is not supplemented. An easy way to obtain 100 percent of your daily requirement for selenium is to eat one Brazil nut a day - it's that simple."
Maintain high levels of dietary antioxidants
"Vitamins A, C, and E are 'ACE' for good immune function. Their role as antioxidants leverages how they work together to combat free radicals, which are associated with not only pollution, but also exercise and immune stresses," Webster said.
"Vitamin C is especially important and is known to underpin antiviral defences. Eating the daily recommended intake of five portions of colourful vegetables will naturally provide these important vitamins."
In an interview with the Australian Academy of Science in 2020, University of Melbourne professor Peter Doherty - who shared the Nobel Prize for Medicine for his research on immunity - said a balanced, healthy diet is far more reliable than 'immune support' supplements.
"Some people believe in things like echinacea and so forth. My understanding is they haven't really checked out all that well when people have done proper trials... We don't know whether any of those things have any validity at all, quite frankly.
"Maintain an adequate diet. If you're in a state of undernutrition, that's certainly a danger. And that's why people in very poor countries and so forth are at risk. We don't know how much being overweight is a risk factor for this virus."