What your snot can reveal about your health
In Ancient Greece, snot was thought to be one of the four bodily fluids responsible for balancing human health and personality. The physician Hippocrates developed a theory stating that phlegm, blood, yellow bile and black bile were the four "humours". A person's balance of these humours could dictate their temperament; an excess of any of them could cause illness. For instance, phlegm was thought to be made in the brain and lungs, and during the cold and wet seasons, it could become too abundant and even cause epilepsy. Somebody with a phlegmatic personality would have a cold, damp and aloof character.
Of course, we now know that snot doesn't affect people's personalities or cause diseases – rather, it helps to protect us from them.
And though nobody likes a runny nose or flinging snot across the room in a sneeze, the mucus in our nasal passages is arguably one of the wonders of the human body. It protects us from intruders, and it has a unique composition that can reveal profound insights into what is going on inside us. Now scientists are hoping to hone the powers of snot to better diagnose and treat everything from Covid-19 to chronic lung conditions.
The gooey substance shields the insides of our nose, moisturising the nasal passages, and trapping any bacteria, viruses, pollens, dirt, dust and pollution trying to get into our body through our airways. Aided by hundreds of tiny hairs, snot is a barrier between the outside world and our inner one.
The adult body produces over 100 millitres of snot over the course of a day but children tend to be much snottier than adults because their bodies are learning to deal with being exposed to all of the world's molecules for the first time, says Daniela Ferreira, a professor of respiratory infection and vaccinology from the University of Oxford in the UK.
With a simple glance, our snot's colour and consistency can already help us glean a little bit about what's going on: snot can be like a visual thermometer. A runny schnozzle with clear mucus suggests the body is likely expelling something that's irritating its sinuses, like pollen or dust. White mucus means a virus may have entered the premises, as the white is caused by the white blood cells called up to fight off intruders. When mucus turns denser and yellowish-green, it's just a lot of dead white blood cells accumulating after having gathered in great numbers and flushing out. If your snot is reddish or pink, it may be a little bloody: maybe you've blown your nose too much and irritated its insides.
But looking at snot is just the first step.
The snot microbiome
While the gut microbiome – the ecosystem of bacteria, viruses, fungi and other microorganisms that inhabit our bodies – is very much in the public consciousness, scientists think that the microbiome in our snot is equally important. In fact, scientists now believe that it's intricately linked to human health and the proper functioning of the immune system.
Everybody has a unique snot microbiome. It is affected by sex, age, location, diet – and even whether you vape. The microbiome's makeup is what helps it fend off intruders, and some of these interactions are subtle. Research from 2024, for instance, found that whether potentially harmful Staphylococcus bacteria survive in the nose and infect a person, causing fever and pus-filled boils, depends on how the snot microbiome's bacteria hold onto iron.
More like this:• How often should you poo?• What your earwax can reveal about your health• How often should you wash your feet?
Ferreira is working to figure out exactly what a healthy snot microbiome looks like so that it can be put in an everyday nasal spray to boost snot health, like taking probiotics for gut health. "Imagine if you could alter what we have in our nose with lots of very good-guy species that stay there and colonise, and do not allow for the bad guys to come in and cause us to get sick," says Ferreira.
Ferreira's colleagues have selected the bacteria they think make up the perfect schnozzle microbiome, and they're testing them to see if these bacteria can take over people's airways and last long enough to impact and improve their health.
Since the snot's microbiome is so tightly linked with the immune system, says Ferreira, they are also studying it to fine-tune how to boost the immune system and even make it more receptive to vaccines. Research suggests that how a body reacts to a vaccine is altered by the type of microbiome a person has. Studies on the Covid-19 vaccine, for example, suggest it affected the snot's microbiome, and in turn, the microbiome affected how efficient the vaccine was.
"The Covid-19 vaccines were great at stopping us from getting sick, but we continued to transmit the virus," says Ferreira. "We could actually develop much better vaccines [so] the next generation people don't even get sick, whether that is Covid-19 or flu or any other respiratory viruses – and it's all there in that snot immunity."
The rise of diag-nosing
While Ferreira's work pinpointing the exact formula for the perfect snot microbiome might take a couple of years, in Sweden, scientists have had a head start by transplanting healthy people's snot into those who are sick with a chronically blocked nose and hay fever, everyday symptoms of rhinosinusitis.
The researchers asked 22 adults to shoot themselves up the nose with a syringe full of snot from healthy friends and partners each day for five days. They discovered that symptoms like cough and facial pain, for instance, dropped by almost 40% for up to three months in at least 16 of the patients. "That was great news to us, and no one reported any negative side effects," says Anders Martensson, a senior consultant in otorhinolaryngology and head and neck surgery from Helsingborg Hospital in Sweden, who led the study. These trials were inspired by work done in other laboratories about gut microbiomes, with faecal transplants, he says.
That first pilot programme, however didn't gather much data about how these people's snot microbiomes changed and what happened to the specific bacteria in their nose, whether they increased, decreased, and so forth. So another larger and more precise trial is underway.
In fact, snot can be a great barrier to chronic nose and lung diseases.
Jennifer Mulligan, an otolaryngologist at the University of Florida, uses snot to study people with chronic rhinosinusitis and nasal polyps – a condition that affects about 5 to 12% of the global population. In the first years of her career, she needed to surgically extract nose tissue from rhinosinusitis patients, but that was invasive and limiting. Now, her research has shown that snot can be an accurate proxy to more closely examine what's happening inside the body when someone develops rhinosinusitis. "We're using it to whittle down who are really the guilty culprits here, who's really driving this condition?" says Mulligan, adding that every patient has a slightly different profile for what's causing their rhinosinusitis.
Similarly, while treatment before was mostly trial and error – varying greatly from patient to patient, and sometimes costing tens of thousands of dollars for treatments lasting months – Mulligan suggests a snot analysis can quickly help identify the right treatment or surgery needed. Several clinical trials for Mulligan's technique are underway worldwide and companies are developing snot-analysing AI systems and devices.
"We have learned so much that we could have never learned with just tissue biopsies. It's completely changed what we know about the disease, and it's going to change the way patients are diagnosed in the future and how they receive treatment," says Mulligan.
Mulligan uses the same snot tools to study what causes people to lose their sense of smell, too. Her team has already found that a vitamin-D nasal spray could potentially help restore a sense of smell in people who have lost it due to inflammation from smoking.
Plus, Mulligan says, what happens in the lungs happens in the nose and vice versa. So these diagnostic tools and therapies can be used for lung diseases too. New research suggests that by simply analysing how much of the IL-26 protein is present in a patient's snot, doctors can tell whether somebody is more or less susceptible to developing chronic obstructive pulmonary disease – a common smoker's disease, and the fourth most widespread cause of death in the world. With snot analyses, patients can be diagnosed early and treated rapidly.
"Snot is the future of personalised medicine. I wholeheartedly believe that," says Mulligan.
*DisclaimerAll content within this column is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. The BBC is not responsible or liable for any diagnosis made by a user based on the content of this site. The BBC is not liable for the contents of any external internet sites listed, nor does it endorse any commercial product or service mentioned or advised on any of the sites. Always consult your own GP if you're in any way concerned about your health.
--
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Telegraph
an hour ago
- Telegraph
I have helped more than 300 people reverse their diabetes – here's how
'The traditional view of type 2 diabetes is that it's chronic and progressive,' says registered dietitian Helen Gowers. This will be a recognisable characterisation of the condition for the 4.1 million people in the UK who have it and, upon diagnosis, were swiftly put on to a lifetime course of medication, typically metformin and then insulin, to keep their blood sugar levels at bay. 'However, our approach is to undo insulin resistance by removing the visceral fat that's clogging up key organs – the root cause of type 2 diabetes – so everything starts working normally again,' Gowers says. 'You can't achieve that with medication, it has to be done through weight loss and diet.' Doctors now recognise that reversing type 2 diabetes through diet is a very real possibility for many patients. A study, published in the journal BMJ Nutrition, Prevention & Health in 2023, showed a diet low in carbohydrates (found in bread, potatoes and pasta) helped 51 per cent of the 186 type 2 diabetes patients involved achieve remission within three years – meaning their blood sugar levels were below the type 2 diabetes range and they no longer needed medication. To spread this method to the masses, Gowers joined the charity Public Health Collaboration in 2021, offering an eight-week diet and lifestyle course called The Lifestyle Club (TLC) for type 2 diabetes and prediabetes patients to help them reverse the condition. So far, more than 1,340 people have completed the course, and based on a recent TLC service evaluation in collaboration with the University of Surrey, she estimates 308 of them will have achieved remission or reversed prediabetes. Their study found a 23 per cent remission rate for a TLC cohort in Guildford after six months, which will have reduced their risk of developing diabetes-related complications, such as heart attacks, strokes and kidney disease. What causes type 2 diabetes and how can it be reversed? Scientists are still trying to unpick the exact mechanism behind type 2 diabetes. However, it is known that a build-up of fat in the liver and pancreas are major contributors. We all have a personal threshold for being able to store body fat, Gowers says. 'Once you've reached that level, the only place you're going to be able to store extra calories is in your abdominal area as visceral fat, which surrounds the liver and pancreas.' Eventually, the liver and pancreas then become clogged up with fat, which contributes to insulin resistance, meaning that the cells stop responding to insulin – a hormone vital for bringing down blood sugar levels. 'The pancreas then churns out more and more insulin as the insulin resistance gets worse to try and overcome it, and it's only when it finally can't produce enough that blood sugar goes up and remains high,' Gowers explains. It is at this point that type 2 diabetes is diagnosed. 'Diabetes is literally just the end of the show.' While needing to pass urine frequently, being very thirsty and feeling very tired are all symptoms, a lot of people experience no symptoms. 'The body's so incredible in the way that it manages all of this quietly,' Gowers says. Is remission possible for everyone? When it comes to putting type 2 diabetes into remission, the goal is to drain the liver and pancreas of fat, so their function can return to normal, reversing insulin resistance – meaning that people can come off their medication. 'For people who have been diagnosed with type 2 diabetes within the last year, that remission rate shoots up to 77 per cent,' Gowers says. 'For prediabetes, it's 93 per cent. The earlier in the journey that you find people, the better.' However, there are cases of patients who had type 2 diabetes for decades being able to reverse it. Even if you're unable to hit remission, there are still benefits of following a low-carb diet in an attempt to reverse it, she notes. Weight loss is one of them. 'We've had people who have had diabetes for 20, 30 years and they make phenomenal progress,' she says. 'They'll reduce their medication, their blood pressure will come down, they'll lose a bit of weight, they'll feel more energetic. There will always be improvements, even if we don't call it remission, so it's definitely worth a go.' How to reverse type 2 diabetes Reduce your sugar and carb intake Cutting out sugar and dramatically reducing your intake of carbohydrates, both of which cause surges in blood glucose, are the main changes needed to reverse type 2 diabetes, Gowers explains. 'You want to reduce them as low as required to achieve your goals, and this varies from person to person,' she says. The reason is that these foods raise insulin levels, and when these are high, you can't lose body fat, Gowers says. A low-carbohydrate diet means having no more than 130g per day. When you do have carbs, it should be whole-grain varieties, such as brown rice, pasta or bread. In practice, this means cutting out food including white bread, rice, pasta, potatoes, crackers and cereal. Patients are advised to cut out added sugar – found in sweets, cakes, biscuits, chocolate and fizzy drinks – and avoid foods that are high in natural sugar, such as honey and certain fruit. While blueberries, strawberries and raspberries are allowed as they are lower in natural sugar, it's recommended not to have some tropical fruit, such as bananas, oranges, grapes, mangoes or pineapple, because their sugar content is very high. It's also key to ditch low-fat foods, which are typically high in sugar. 'Go for full-fat dairy, fish, meat and eggs,' Gowers says. 'The natural fat that comes with those foods is fine. It's turning the current dietary guidelines on their head, really.' Consider options such as coleslaw for a tasty, low-carb side, and cheese, avocado and mayonnaise can also be enjoyed, she notes. Breakfast is a good place to start, when it comes to adopting the low-carb diet. 'People tend to consume a lot of carbs at breakfast, whether it's bread, cereal or pastries,' Gowers says. 'The human body only needs one teaspoon of glucose in the bloodstream at any one time and if you're having toast, cereal and orange juice for breakfast, that's going to break down into about 16 teaspoons of sugar. 'Full-fat yogurt and berries or eggs won't cause spikes in blood glucose and they're really nutrient-dense, meaning they will fill you up for the rest of the morning.' Fasting, which can be done by pushing back your first meal of the day until lunchtime, can also be a helpful tool in sticking to the low-carb diet, Gowers notes. You don't need to be worried about skipping a meal, she says. 'You're not starving – your body is going to be using fat stores, which is great. Think of it in terms of, I can either fuel my body with food or I can use my own fat stores as fuel.' However, she recommends anyone taking medication to seek advice before changing their meal patterns. Rather than a quick fix, the idea is that low-carb and low or no sugar are diet principles that you carry forward for life, she says. 'Some people might go all out for eight weeks to reverse their diabetes and then think, 'There's no way they can be as strict in the long term,' so make concessions to keep their diabetes status within the range they're happy with,' Gowers notes. This may mean that they are able to reduce their medication or put themselves into the prediabetes category, rather than fully reversing it, she says. Base meals on 'real' foods If you begin cutting out carbohydrates and sugar, you may naturally find yourself gravitating towards whole foods, such as protein, vegetables and dairy, Gowers says. 'Make sure you have a good amount of veg to fill you up – it also offers lots of fibre,' she notes. A large portion of broccoli, courgette or green beans can substitute mash, pasta or rice – and they can still be covered with gravy, Bolognese or curry. Thinly sliced cabbage that has been lightly boiled is a great low-carb option instead of tagliatelle, she notes. 'The idea is that the fewer carbs you're eating, your body shifts to burning fat, so you're going to be able to utilise your stored fat to fuel your body, rather than the sugar you were eating before,' she explains. 'The note of caution is that you don't want to add loads of extra fat when you're trying to lose weight – but it will fill you up. It's just eating real food and the fat that comes with that food.' It's also recommended not to eat too much processed meat, which includes ham, bacon and sausages. Snacking is generally not recommended, though some crudités with full-fat hummus, a couple of squares of dark chocolate or a few plain nuts won't spike your blood sugar or leave you feeling hungry, she says. 'But people find that they don't need all of those extra snacks that they were used to having before.' Have enough water and salt In the early stages of following the low-carb diet, it's important to make sure you're drinking plenty of water and having enough salt, Gowers says. 'When you switch over from having a diet that's very high in carbohydrates to low-carb, you may initially become dehydrated and get headaches or constipation,' she says. 'Insulin disrupts the way you process salt so you're releasing a lot of the salt and water that your kidneys were holding on to,' she explains. 'One of the reasons that people lose weight quite quickly is because you're losing all of that water retention.' As a result, you need to make sure you're replacing the lost salt, which you can simply do by adding salt to your meals as you cook them or adding an extra stock cube to your meals, as these are high in salt, she says. 'Having sufficient water and salt means you're not going to be dehydrated and you're less likely to get headaches, cramps and feel a bit lethargic as you transition to using fat as your fuel.' Have a support network When overhauling your diet, it's vital to have a support network around you to help you stay on track, Gowers says. 'Long-term support is what makes the difference,' she notes. It's especially important that it's available when people feel like they've drifted off their diet and are trying to get back on it again. On the eight-week TLC course, there are weekly 90-minute Zoom sessions overseen by a health coach. Once the course is finished, people are invited to monthly catch-up meetings, where there are guest speakers, such as consultants and chefs. There are also Facebook and WhatsApp groups for people to chat to each other or suggest low-carb meal ideas, and some meet for coffee or go for walks together, she says. 'It's keeping the momentum going,' she says. If you don't join the course, you can enlist the help of friends and family to keep you on track. It's initial intensive support, as well as the long-term support after the course, that is vital to ensure patients stick to the healthy changes they've made, Gowers explains. 'People can dip in and dip out; it's not that everybody needs the support all the time but you've got to be there so that when someone needs it, you're there to help and get them back on track.' Prioritise diet over exercise While exercise is excellent for health, diet is the focus when it comes to reversing type 2 diabetes, according to Gowers. 'It's what's going to give you 70 per cent of the benefits,' she says. However, you're much more likely to maintain your dietary changes if you bring in some exercise as well, so it's important to be more active, even if it's not straight away when you first try the diet, she notes. 'Once you've regained some metabolic health, you've lost a bit of weight, you're feeling so much better, you are much more likely to want to do some exercise. 'Don't beat yourself up trying to go to the gym three times a week at the beginning; start with diet and naturally you will feel more like moving about as time goes on.'
Daily Mail
an hour ago
- Daily Mail
Slash your risk of bowel and colon cancer with these very surprising foods: They contain the key nutrient proven to help - and which most overlook. Now doctors reveal exactly what to eat
A fibre-rich diet is important for our gut health and helps to keep our bowel habits regular. And more recently, research has suggested it can lower cholesterol, improve heart health, reduce our risk of type 2 diabetes and – because it can help you feel fuller for longer – it's even good for weight management.
Daily Mail
an hour ago
- Daily Mail
I have lost 3st on Mounjaro and now my hair is falling out: DR MARTIN SCURR reveals the troubling cause – and shares a NEW jab side effect everyone is missing
I have lost 3st (19kg) in six months with Mounjaro injections, but I've noticed my hair is getting much thinner. Is there anything I can do? Frances Roberts, Brighton.
