Re-tune your immune system

Re-tune your immune system

Some people seem to be able to catch every virus going around, from coughs to stomach bugs, while others do not. So, what is the secret?

You can keep your immune system revved up and raring to go by taking control of the factors that affect it, though there are still factors such as age, gender, genes or whether you’ve been infected by the pathogen before that are out-of-the-user's powers.

Here’s the good news – read on:


The human gut is riddled with bacteria. 

That's a good thing, too, as not only does good bacteria help you digest food and keep your immune system healthy, but they also introduce important diversity to your microbiome.

The gut flora, as it is known, competes with harmful microbes for nutrients and physical space. It also releases antimicrobial compounds to keep these bad guys at bay, along with communicating with the immune system in more complex ways that we're only just starting to unravel. 

The health of your gut is important for a variety of reasons, thus given all this, it is not surprising that damaging your gut flora can leave you prone to bacterial infections. 

Probiotics are good for you as they nurture good bacteria. So instead of ‘nuking’ them, nurture the friendly bacteria with yogurt drinks each day, designed to boost the number of good bacteria.

After initial doubts that this approach would do anything useful for delivering enough microbes, studies are starting to show results. One study found probiotics could help treat gut infections and even prevent coughs and colds.


We like to think some things we eat can help ward off infections, seen in old-fashioned beliefs in the healing powers of chicken soup to more modern obsessions with so-called superfoods. 

There is a lack of evidence for most of these beliefs, but there are dietary interventions that appear to work. 

Various supplements do have immune-boosting properties which we will outline below:

Zinc supplements come out as the best to prevent colds and shorten their duration, if taken within 24 hours of displaying symptoms as zinc may work by stopping the cold virus from replicating or preventing it from gaining entry to cells lining the airways. 

There is some evidence that vitamin C might reduce symptoms of colds to an extent, but it’s not as effective or efficient as believed to be.

Vitamin D, meanwhile, appears to do the same for the innate arm of the immune system, especially among people living at latitudes where there isn’t enough winter sunlight for their skin to synthesise the molecule. 

A 2017 review of the evidence for taking vitamin D supplementation concluded that it prevents upper respiratory tract infections. 

One of the best ways to actually support your immune system is by eating plenty of fruit and vegetables.

The benefits of doing this is shown in the variety of not just vitamins but thousands of other compounds called phytochemicals you receive. These phytochemicals have numerous beneficial effects that are only just being understood.

In addition to focusing on the quality of food, it's important for people to also look at how much they're eating. Those who are obese have a higher likelihood for having different types of infections, including respiratory, skin and urinary infections.

When people pile on the pounds, it not only makes breathing harder but excess fat releases chemical signals that interfere with our immune functioning.

But be careful with how you lose the pounds; there are many harmful effects of yo-yo dieting. Frequent cycles of weight loss and regain seem to reduce the performance of natural killer cells, an important branch in your immune system that targets cancerous cells and those infected with viruses.


Foods such as dairy products and fish contain vitamin D, but it’s mostly made in the skin when exposed to the sun's ultraviolet rays.

It appears that vitamin D has a significant role in regulating the immune system, such as stopping it from reacting to things inappropriately. The first clue that this was the case was the higher rate of autoimmune disorders in parts of the world with less sunlight.

Since then, Vitamin D has been shown to have a suppressive effect on the immune system. It does this by inhibiting the proliferation of immune cells and the signalling factors that spur them into action. 

Researchers are studying this compound as a way of stopping people from rejecting organ transplants.

Sunshine is an essential source of vitamin D, but its effects stretch beyond those. Melatonin - a hormone secreted by a gland in the brain in response to changes in light - stimulates certain kinds of immune cells.

Vitamin D is also vital for calcium absorption and bone health. 


It can be hard to motivate yourself to exercise, but now there is yet another reason to do so: even short bursts of exercise give your immune system a temporary boost.

When 500 adults were tracked for 12 weeks, those who were the most physically active – five sessions or more of aerobic exercise a week – spent nearly half the number of days sick with an upper respiratory tract infection such as a cold or tonsillitis (British Journal of Sports Medicine, vol 45, p 987). 

As your heart gets pumping, it flushes immune cells which have been stuck in blood vessel walls away and into circulation where they can do their stuff, says Mike Gleeson from Loughborough University.

When you exercise, levels of these cells in the blood double during exercise; meaning your body's immune system is energized and more able to respond during an infection or illness. "Exercise increases immunosurveillance," says Gleeson."

It is possible to overdo it, but you would have to be extremely dedicated. 

Too much exercise can have a similar effect to stress, raising levels of the stress hormone, cortisol, that change the function of your immune cells. "Even though there's an increase in cell count, their ability is depressed," says Gleeson. He recommends exercising little and often for no more than 2 hours at once; “Restrict yourself into moderate activity such as jogging or swimming if necessary”.


How much shut-eye did you get last night? Even a moderate lack of sleep can put you at greater risk of catching a bug.

In a study, the sleeping habits of 153 healthy adults were recorded before they were given a sniff of a cold virus. It turned out that people who slept for less than 7 hours per night found themselves almost three times as likely to catch colds compared with the rest of the group (Archives of Internal Medicine, vol 169, p 62).

This suggests it is important to make sure you are well rested before getting vaccinated, says Mark Opp, a neurobiologist at the University of Washington. He recommends at least 8 hours and 20 minutes nightly for optimal results.


Close your eyes. Count to 10. Whatever you do, stay calm. Stress can weaken the immune system transiently but significantly. 

Despite its New-Age associations, studying the links between mind and body is now a respectable field of research. This is now being referred to by some as "psychoneuroimmunology".

In the field of immunology, one study looks at immune responses after getting a vaccine. Ronald Glaser from Ohio State University in Columbus showed that people stressed out due to taking care of a relative with Alzheimer’s disease had worse antibody and T-cell reactions while being vaccinated against flu viruses; their wounds healed slower as well and they also caught more throat infections (Annals of the New York Academy of Sciences, vol 840, p 649). 

The brain and immune system are connected through a complex network of pathways, but some key players seem to be cortisol and noradrenaline.

These bind to receptors on immune cells and interfere with their ability to respond. This leaves us more susceptible as antigens are not responded to, which causes infections.

Though a little bit of the bad stuff might be beneficial; a recent analysis of over 300 studies found that a short stressful experience, like public speaking-boosts our immune cells (Psychological Bulletin, vol 130, p 601). 

“A slight elevation of stress hormones is good for you,” says Bruce Rabin at the University of Pittsburgh in Pennsylvania. He doesn’t recommend setting out to get stressed, but instead advises learning how to cope better with any stress that comes along.

“Be optimistic, fit, have a sense of humour,” he suggests. Most important of all is to keep your friends. 

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