Seven easy tweaks to keep winter lurgies at bay
As temperatures drop and the frost appears, our thoughts turn to staying healthy through the winter months – especially after the past few years of Covid and nasty flu infections. If you were one of those people who had a cold that wouldn’t shift last year you won’t be surprised to hear that researchers from Queen Mary University of London have confirmed that – like the unlucky few who develop long Covid – symptoms of respiratory infections such as the common cold can also persist for more than a month, causing coughs, stomach pain and diarrhoea.
Whether or not a long cold has you in its grips, many of us could benefit from focusing more on our immunity, suggests Sheena Cruickshank, immunologist and professor in biomedical sciences and public engagement at the University of Manchester. “Modern life is rubbish for our health,” she summarises. “It favours sedentary lifestyles, being in front of computers, eating convenience food and feeling stressed. All those things are bad for our immune systems.”
In fact, they can cause a “very common” but little-discussed condition called meta-inflammation. A healthy immune system involves lots of different types of white blood cells, working together and in balance, Cruickshank says. “With meta-inflammation, they become imbalanced. You get more of the rapid responders like neutrophils, which trigger inflammation, and less of the specific cells, lymphocytes, which actually make antibodies and kill viruses.” Essentially, you’re more at risk from lurking lurgies. But don’t panic. “If you fix your diet and lifestyle, it can return to normal. It’s not so much a boost, as a rebalance.” Here’s how you do it.
Don’t panic, no one is suggesting you spend the winter triathlon training. “In fact, really vigorous workouts, when you’re not used to them, put your body under a lot of stress and that is bad for your immune system,” says Cruickshank. “Exercising regularly at a moderate level seems to be best for your immune response. It helps your white blood cells circulate and perform better, and there seems to be a positive effect on those cells that kill viruses – they work a little better.”
Try regular brisk walks, taking the stairs, or aerobics classes if you enjoy them. “Research suggests you have a much reduced risk of developing upper respiratory tract infections when you regularly do something that gets your heart pumping for a sustained period of time,” explains Cruickshank.
“Not only do stress hormones negatively affect your immune response, but stress often alters our sleep patterns – and lack of sleep has been linked to changes in our immune response too,” says Cruickshank. A study at the University of Florida in the US found that eight days of intense meditation causes robust activation of the immune system. The findings are believed to be the first genomic study of how meditation affects the biological processes involved in disease development. Before you snort about the likelihood of locating eight days of me-time in your overstuffed schedule, Cruickshank explains that small changes to your habits can really help. “Start turning your screens off at 8pm,” she suggests. “Or find just 10 minutes to take a mindful walk or do a little bit of yoga.”
In the past we were all encouraged to take vitamin C tablets to avoid the common cold but “vitamin D is more important”, Cruickshank says. “The healthy functioning of your immune system depends on a complex mix of vitamins and minerals including iron and zinc. It’s difficult to pick one above any other. But vitamin D has been linked to the function of our lymphocytes. And it’s one vitamin that many of us are lacking, particularly in the winter months.”
Our bodies can also store vitamin D because it is soluble in fat, unlike vitamin C which (as a water-soluble vitamin) is transported to your tissues via body fluids, with any surplus exiting the body in your urine. “There’s evidence that if you take vitamin D supplements you may handle a cold slightly better,” she says.
The food we eat has the single biggest impact on our immune system, says Cruickshank. “We’re also learning more and more about the important role metabolism plays in helping our immune system function properly. It’s a really fast-growing area of immunology.” Our metabolism alters the way that our immune cells are programmed and function, she explains, and our immune cells contain receptors and pathways that recognise metabolites (small molecules produced as a consequence of metabolism).
So how should we alter our diet in response to this growing awareness? “I don’t think the research is at the stage of making clinical recommendations on it,” she says. “But being sensible about how much sugar and fat we consume is advisable.” The Western diet tends to be rich in fats and sugar and low in fibre, she says, and we know that this is a key driver of meta-inflammation.
Several studies have suggested that Dash (Dietary Approaches to Stop Hypertension) – a diet rich in anti-inflammatory fruits, vegetables, wholegrains, and low-fat dairy foods – could be a useful tool in reducing inflammation and targeting meta-inflammation specifically. It has also been shown to boost your metabolism. A 2011 study found that adults who ate at least three servings of fruit per day had fewer upper respiratory tract infections than those who did not.
“Not only do 70 per cent of your immune cells live in your gut, but your gut microbiome is critical in training and developing your immune system, so looking after its collection of friendly gut bacteria can help support your immune system to function at its best,” says Dr Emily Leeming, scientist at King’s College London, registered dietitian and author of the forthcoming book Genius Gut.
Dr Leeming suggests eating fibre-rich foods such as beans and legumes, fruits, vegetables, wholegrains, nuts and seeds. “Fibre is king when it comes to your gut microbiome. It’s their favourite food.” A wide range of different coloured fruits and vegetables will help too: “Polyphenols are a group of antioxidants that give fruit and vegetables their colour. Your gut bacteria also like to feed on different ones, from the red in a tomato to the green in spinach.” Meanwhile: “Fermented foods like kefir, kimchi and sauerkraut have been linked to lower levels of inflammation in your body, helping your immune system to recalibrate into a healthier state.”
The good news is that you can improve your gut health very quickly. “Your gut microbiome can rapidly change within 24 to 48 hours in response to what you eat, likely giving us a rapid health boost,” says Dr Leeming.
“Quality sleep profoundly influences our immune system’s ability to combat colds and infections,” says Dr Guy Meadows, co-founder and clinical lead of Sleep School in London. “A study involving 160 healthy individuals revealed that those who slept less than seven hours were nearly 4.5 times more likely to contract a common cold.”
During sleep, our immune system becomes more active, he explains, “leading to increased production of cytokines and other immune molecules crucial for effectively combating infections. Moreover, sleep allows the body to rest and recover, facilitating a robust response to pathogens.”
The amount of sleep your immune system requires is variable, but most adults need between seven and nine hours for optimum health, says Dr Meadows, while recent research suggests that sleeping for less than six hours or more than 10 hours could have a negative affect on your immune system.
Your white blood cells aren’t the only things in your body working to protect you from colds. “We’re covered in all sorts of barriers,” says Cruickshank. “Some you can see, like your skin. But the inside of your nose, throat and gut also have cell linings that make antimicrobial agents. Your nose hairs help trap particulates too.” Both need moisture to operate at their best. So if you sit, or sleep, in a dry environment (windows closed, central heating on) neither will work quite so well. Opening a window, or investing in a humidifier, is a good idea.
Then there’s air pollution. Cruickshank says: “Pollution can damage some of those linings. Some pollutants also seem to affect the function of some of our white blood cells, a type called macrophage, which try to gobble up infectious agents.”
Surprisingly, cycling or walking can expose you to fewer pollutants than driving with the windows closed, she says, and at home “house plants can be quite effective in trapping some of the pollutants”.
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