Feeding the bugs living in your gut is one of the best ways to keep yourself fighting fit and avoid colds and flu. Photo / 123rf
Feeding the bugs living in your gut is one of the best ways to keep yourself fighting fit and avoid colds and flu. Photo / 123rf
Immunologist Dr Jenna Macciochi shares her top tips to stay fighting fit
Now is the time to start picking up habits that can keep your immune system fighting fit. Feeding the bugs living in your gut is one of the best ways to do this.
Unlike your digestiveor respiratory systems, which are made up of organs, the immune system is made up of cells located throughout the body.
Around 70% of these cells are in the gut, while the rest are congregated at the body’s barriers, like the airways and skin, as well as the circulatory and lymphatic systems.
Their job is to perform constant surveillance for bacteria and viruses that could harm our health and fight these off. But, when functioning properly, they also let harmless substances pass through our system and calm inflammation in the body at the end of an infection. Most of these processes occur in the gut, so we need it to be really well fortified. This is what I advise all of my patients to do.
It’s no secret that our gut loves fibre. Unlike other nutrients, fibre isn’t broken down by digestive enzymes. Instead, it is fermented by microbes in our gut, a process which creates metabolites. These compounds are our microbes’ waste products but act like our own personal pharmacy.
They teach the immune cells to be more tolerant of what’s passing through our gut (which is key in preventing allergies) and also reduce unwanted inflammation (which contributes to the onset of Type 2 diabetes, fatty liver disease and heart disease). Additionally, research shows that these metabolites allow our gut and lungs to communicate, which has been shown to improve the immune response in our lungs when it encounters viruses.
Essentially, this all means that not including enough fibre in our diet will prevent our immune system from functioning optimally. In the UK, average fibre intake for adults is 18g per day when we should be eating 30g (more is even better but build up your intake slowly).
Vegetables, fruit, beans, lentils, nuts, seeds and wholegrains are some of the best sources. To get more in your diet, sprinkle seeds into breakfast and lunch, add an extra portion of vegetables to your plate and pour a tin of mixed beans into dinners like spaghetti bolognese or chilli. These are tiny tweaks but will make a world of difference. As well as the short-term effects of improving our immune health, it will also reduce the risk of heart disease, Type 2 diabetes and bowel cancer in the future.
2. Try fermented foods to reduce unwanted inflammation
Yoghurt, cheese, olives, kefir (a milk-based drink), kombucha (made from black tea) and kimchi (a Korean cabbage-based dish) are all types of fermented foods (those that have added microorganisms, like yeast or bacteria). While fermentation was originally used to preserve foods, we now know that it benefits our gut health and our immune system.
A study from the Stanford School of Medicine, which had participants include fermented foods in their diet for 10 weeks, found that there was a wider variety of microbes in their gut (which is known to benefit health) and their immune cells had calmed down, reducing inflammation in the body. This effect wasn’t seen in the control group, who didn’t include fermented foods in their diet. It means the fermented foods enhanced immune system function, reduced unwanted inflammation and there was less age-related decline.
So alongside building up your fibre intake, add in more fermented foods. Have yoghurt for breakfast, add olives to salads and give kimchi a try. As a result of pasteurisation, fermented dairy products like yoghurt and cheese have fewer microbes than the likes of kimchi and kombucha but still count and benefit our health. While there’s not a set amount of fermented food we should include in our diet, generally, the more the better.
Fermented foods like kimchi and kombucha can reduce inflammation and support immunity. Photo / 123rf
3. Cut back on alcohol until Christmas
While most of us won’t want to do it, I highly recommend reducing your alcohol intake for your gut and immune health.
It’s a toxin and causes inflammation in our delicate gut barrier, which isn’t good for the immune system. One study found that people who drink frequently have fewer lymphocytes (a type of immune cell that fights off infections) and suffer more viral and bacterial infections.
I’d encourage people to explore having a period without alcohol and see if they notice a difference in how they’re feeling. It can be difficult to do if your routine is to have a few glasses of wine over the week but now is a good time to give it a go.
Swap alcohol for a glass of kombucha or an alcohol-free spirit with soda or tonic water.
Drinking alcohol regularly can reduce your immune cell count, leading to more frequent infections. Photo / 123rf
4. Be savvy about food labels
Ultra-processed foods (UPFs) are typically high in fat, sugar and salt, contain industrial compounds to give food a longer shelf life and are easy to over-consume.
While it’s unrealistic to completely remove them from our diets, be mindful about the space they are taking up in your diet. If you’re eating too many, you’re not going to be getting enough fibre, which is crucial for gut and immune health.
UPFs have now been linked to unwanted inflammation, which is thought to be in part down to how these foods upset the gut microbiome. These foods are thought to increase the number of harmful microbes in our gut.
We are just beginning to uncover how UPF consumption is causing low-grade inflammation, immune deregulation and thus setting the stage for age-related disease. This phenomenon, known as “meta-inflammation”, is particularly concerning because its roots are planted early, long before symptoms of chronic disease like heart disease and certain cancers show up.
Pay attention to food labels as a lot of the ingredients UPFs contain, such as emulsifiers, are known to trigger inflammation and dampen our immune system. They are thought to have an abrasive effect on the gut barrier, which can lead to a bacteria that is good in our gut leaking into the bloodstream, where it can be harmful, trigger inflammation and turn on the immune system. It can be tricky to cut back, as UPFs are hard to resist. Their hyperpalatable nature and their impact on gut-brain satiety signals make them addictive.
Check your food labels. Ultra-processed foods can disrupt gut microbes, triggering inflammation and weakening immune response. Photo / 123rf
Immune system FAQs
Can you eat off a cold once it’s already started?
This has not been scientifically proven. We have some evidence that rest and supplementing with vitamin C and zinc upon onset of symptoms may help. No single food is going to create a forcefield around you, but a balanced diet can help the immune system function at its best. Though it is normal for a healthy adult to experience a couple of colds a year.
What can I do to speed up recovery?
Don’t power on – rest. It’s the main thing that people overlook. When you get an infection, your immune system starts an inflammatory response which signals the brain to begin “sickness behaviours” like feeling tired. This is designed to give you the best chance of getting well quickly. That means taking time off work, exercise and socialising to free up energy for the immune system.
Regular exercise supports immune health, but rest is key to recovery if you’re already sick. Photo / 123rf
Does taking supplements help prevent colds?
While certain supplements, like zinc and vitamins D and C, can support immune health, they shouldn’t replace a balanced diet. However, taking excessive amounts of any supplements won’t prevent colds and may cause other health issues. It’s best to meet your nutritional needs through a variety of whole foods. Vitamin D, in particular, is essential during the winter months, as we get less sunlight, which can affect immune function. The NHS recommends 10 micrograms per day.
Nutritional supplements like magnesium and 5-HTP may aid sleep and testosterone. Photo / 123rf
