It’s the reason a stressful event can leave us feeling run down, or trigger a recurrence of cold sores, for instance. “A cold sore is a virus. It’s latent in your body and your immune system is keeping it in check, but when your immune system isn’t working so well, the virus can spring back into life,” says Cruickshank. “That’s why we often see infections we’re managing quite well recur. Another is chicken pox, which causes shingles in older people.”
Research suggests, too, that natural stressors can disturb the balance of lymphocytes that recognise external parasites or bacteria, she adds – hence the fact stress triggers allergies in those who are prone. “It could be, if you have asthma, or an allergic reaction, that you will get it worse when you have some types of stress. And you’ll be less able to instantly cope with viral infections.”
It doesn’t help, adds Cruickshank, that under pressure, we sleep less well and engage in unhealthy behaviours such as comfort eating – all of which impact immunity. Indeed, during this period of unprecedented stress, it’s all the more important to ensure you’re doing what you can to support your immune system.
Nourish your gut bacteria
Diet is vital – what we eat has a profound impact on the gut microbiome, which Dr Jenna Macciochi, immunologist and author of Immunity: The Science of Staying Well, describes as “the instruction manual for your immune system.” Essentially, our gut bugs digest the fibre in plant foods we eat, creating by-products extremely important to health, says Macciochi.
“They’re like our own personalised pharmacy. They enter our bloodstream, shaping and educating our immune cells all over our body, telling them what to do, helping remove any baseline inflammation in our system, calibrating our immune system so it can function well.”
A Hong Kong observational study, published in the journal Gut last week, found that patients admitted to hospital with Covid had less of the gut bacteria known to influence the immune response to infection than other patients. These findings, wrote the authors, suggest “the gut microbiome is involved in the magnitude of Covid severity, possibly via modulating host immune responses.”
Whether those patients had those differences to start with, or were a consequence of getting severe Covid, isn’t known. However, Macciochi says, “It’s known that with colds and flu, alterations to the gut microbiome can affect how severely you suffer, and even how frequently you pick up those infections.”
Rather than obsess about having this or that species of gut bacteria (their output is more important than their composition) she advises eating to nourish your microbiome ecosystem, by getting all six plant-based food groups into your diet – fruit, vegetables, wholegrains, legumes, nuts and seeds (and herbs and spices too.) “Forget about five a day. Aim for 30 types per week. You might choose different vegetables, or add lentils to a bolognese. Start slowly, and build up gently. This will allow the bugs in your digestive system to adapt.”
Mostly, we’re nurturing what’s there – though eating fermented foods like unpasteurised yoghurts, kefir, sauerkraut, and probiotics containing lactobacillus and bifidobacteria can introduce bacteria beneficial to the immune system into your gut – and some fresh fruit carries its own microbiome, even if you wash it. And here’s another reason to spend time in nature. “Getting out in green space, breathing and swallowing the microbiome in the air is also seeding our gut,” says Macciochi. “Urban areas generally have a less diverse, less favourable microbiome.”
We know that exercise is mentally and physically destressing, but Cruickshank notes too that “regular moderate exercise gets your immune cells mobilised, it gets your immune cells working better.” While experts advise any activity you enjoy, the pleasure (or punishment) of cold water swimming, in which interest has soared during the pandemic – has particular benefits.
It’s not just the life-affirming sensation, which many say helps banish anxiety and depression. Mike Tipton, Professor of Human and Applied Physiology at the University of Portsmouth, has studied how volunteers react to a dip in icy water – and found that after only six immersions, the cold water shock response (where you gasp, hyperventilate, panic.…) is halved. Your heart rate rises half as much as it did initially, you panic less and find it easier to control your breathing. Importantly, this adaptation to the stress of leaping into near freezing water could also make people less reactive to everyday stress.
Subjecting yourself to a little bit of controlled, safe stress helps improve your body’s stress response, says Macciochi. That might be cold water swimming, a cold shower, or an exercise that pushes you a little further such as strength training, high intensity interval training, climbing or running.
We only have one stress response – whether we’re running for our life or worried about a deadline, she says. “Jumping into icy cold water stimulates that stress chemistry, but in a controlled and safe way. It’s building a resilience to the stress response in the body.” But whatever activity you choose, don’t overdo it: “Keep it short-term – that’s what stress is designed for,” sayd Macciochi.
There are gentler ways too of managing stress, such as meditation and mindfulness. That said, attempting to meditate in stressful moments might tip us into meltdown. “The most immediate tool is just breathing,” says Macciochi, who recommends simply slowing down your exhale.
A grim narrow focus, such as a screen, isn’t conducive to relaxation, so it’s also soothing to widen our gaze to a panoramic vision, she adds. “Go for a walk, go to a window, look far away – again, it sends a signal to the brain that you’re relaxed.”
Sleep on it
Sleep – which has been hugely disrupted by the pandemic – is “the foundation of the immune system,” says Macciochi, and worrying about insomnia only exacerbates it. However, she says, we can help ourselves by giving our body cues throughout the day that help set our circadian rhythm. That starts with getting up at the same time every morning. Avoid caffeine in the afternoon and have a wind-down period in the evening – with no devices, laptops or screens close to your face for an hour before bedtime as “the light from these devices gives your brain the signal that it’s daylight”.
Stretch or do yoga if it relaxes you. Or, weather permitting, watch the sun go down. “There’s new evidence that the type of light that we see during a sunset is really important for setting that biological clock within us,” says Macciochi. A reasonably hot bath or shower about an hour before bed will also prime you to sleep.
The final essential ingredient? Don’t be mean to yourself. “Practising self-compassion has been scientifically shown to help us be more successful in engaging in any changes we want to make,’ says Macciochi. Self-compassion means taking mindful moments in the day, being forgiving of yourself, letting go of perfectionism. “Sometimes half-right is good enough. It’s so important right now to be kind to ourselves – and it’s also associated with improvements to the immune system.” Well then – there really is no excuse.