We’ve all heard the old expression ‘coughs and sneezes spread diseases – trap those germs in your handkerchiefs’. And grandma was quite right to check you had your hankie in winter – the viruses that cause coughs and colds largely get into (and come out of) your system through your mouth and nose. If you have a cold, you’ll share a horrifying 3,000 droplets or so every time you cough – and about 40,000 droplets when you sneeze.
But catching colds depends on more than just being exposed to viruses – it’s also about how your body reacts to them. That’s where your immune system – the trillions of cells in your body that help you fight off disease - comes in. And your gut health is central to how effectively your immune system works.
How does your immune system work?
Your immune system includes many different types of white blood cells. These are constantly circulating in your bloodstream, waiting to spring into action. Some produce antibodies, which bind to invaders and neutralise them. Others swallow invading cells and destroy them.
There’s also your lymph system – a sophisticated network that delivers white blood cells and more to where they’re needed. Tiny tubes called lymphatic capillaries pick up fluid from your tissues, moving it into bigger tubes called lymphatic vessels. These vessels are like the train tracks in a railway network, carrying lymph round your body with ‘stations’ – lymph nodes – that monitor, filter and regulate the lymph.
If you’re exposed to an infection, your lymph system directs white blood cells to where they’re needed. They congregate in your lymph nodes, which is why you can get swollen glands (nodes) in your neck if you have, say, tonsillitis.
But almost 70% of the whole immune system lie in the gut, in so-called gut-associated lymphoid tissue (GALT). What's more, around 80 per cent of all antibody-producing immune cells are based here. Because GALT interacts so closely with every other part of the body, your gut has a huge impact on your overall immunity.
What has gut health got to do with colds?
Good gut health plays a major role in your body’s ability to fight off infection, by promoting a healthy immune system. As well as white blood cells and antibodies, it can influence substances called cytokines which communicate between different parts of the immune system.
By contrast, an imbalance of your gut microbiome – the trillions of bacteria that live naturally in your gut – can hamper your immune system’s ability to function at top capacity. This imbalance in the microbiome is called dysbiosis.
Your gut is in constant communication with your lungs and upper airways – so-called gut-lung crosstalk. Many lung problems – including asthma and chest infections – have been linked to dysbiosis. Recent studies have shown that dysbiosis also make it harder for the immune system to fight off the viruses that cause the common cold.
Dysbiosis can play a part in more serious chest infections, too. For instance, in a study of people with influenza, those who also had dysbiosis were at higher risk of developing the serious lung complication of pneumonia due to a bacterium called pneumococcus.
Can probiotics help ward off the common cold?
Probiotic supplements aim to top up healthy bacteria within the gut microbiome, tipping the balance away from dysbiosis. Given that an unhealthy balance can make you more prone to coughs and colds (called upper respiratory tract infections or URTIs in medical jargon), could improving the quality of your microbiome with probiotics help ward them off?
Several studies have aimed to answer this question. Because some of the studies are small, combining the data and finding into a ‘systematic review’ can paint a more reliable picture.
A systematic review of 24 studies looking at almost 7000 people ranging from babies to older adults showed probiotics may cut:
- The chance of getting at least one URTI by almost a quarter (24%)
- The chance of getting at least 3 URTIs in a season by 41%
- The average time the URTI lasts by 1.22 days
- The need for antibiotics by more than two-fifths (42%)
Importantly, the review didn’t find any evidence of harm from taking the probiotics. Not all the studies looked at whether taking probiotics cut time away from work, school or childcare, so it wasn’t clear if this was also reduced by taking probiotics.
How can you help your gut health during cold season?
The top tips for good gut health during cold season hold true all year round.
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Stay away from ultra-processed foods – anything where artificial colours, preservatives and flavours have been added e.g. cakes, biscuits, hotdogs. As a rule of thumb, if a food doesn’t contain the ingredients commonly found in your pantry, it’s ultra-processed.
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But not all processed foods are bad e.g. tinned or frozen fruit and veg, cheese. Many processed food – especially tinned or frozen fruit (in juice, not syrup), veg and beans – can actually contribute to a healthy balanced diet.
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Veg out. The good bacteria in your gut microbiome thrive on veg – the wider the range the better. Load up on winter vegetables like carrots, parsnips, beets, brussels sprouts, cabbage, leeks and kale.
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Unrefined carbs like wholegrain and wholemeal flour are an excellent source of fibre. Fibre is a gut health megastar!
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Pulse it up. Beans, lentils and pulses are a delicious and healthy way of bulking out winter stews and soups – and they’re kind to your pocket too.
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Manage your stress. Whether it’s meditation, relaxation exercises, yoga, mindfulness or just a regular warm bath with some scented candles and a good book, whatever works for you to relax you and reduce your stress works for your gut health too.
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Get your ZZZs. A good night’s sleep isn’t a luxury, it’s a necessity for your overall health and immunity. Switch off electronics from an hour before bed, turn your bedroom into a haven of peace and quiet and try and go to bed and get up at the same time each day to avoid confusing your body clock.
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Add a probiotic. A clinically proven probiotic supplement is an addition, rather than an alternative, to the lifestyle tips above. But it can add to the benefits of a healthy lifestyle and support your immunity to coughs and colds.
Discover more tips to help support your gut-immune connection.
Sources
Coughs and Sneezes: Their Role in Transmission of Respiratory Viral Infections, Including SARS-CoV-2. Am J Respir Crit Care Med. (2020) Link.
The lung-gut crosstalk in respiratory and inflammatory bowel disease. Front Cell Infect Microbiol. (2023) Link.
Effects of microbiota on immune development: Rhinovirus-mediated modulation of host immunity under homeostasis. Allergy Medicine. (2025). Link.
Gut dysbiosis during influenza contributes to pulmonary pneumococcal superinfection through altered short-chain fatty acid production. Cell Rep. (2020). Link.
Allergy and the gastrointestinal system. Clin Exp Immunol. (2008). Link.
Probiotics for preventing acute upper respiratory tract infections. Cochrane Database of Systematic Reviews. (2022). Link.
