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What’s the link between gut bacteria and your immune system?

23 Nov 2022 • 1 min read

Could keeping your gut in the best possible condition support your immune system as well as your digestive health? There are more and more studies that show a link between maintaining a healthy balance of gut bacteria and susceptibility to illness and disease. So, if a well-nourished gut is the secret to how to support your immune system, what should we eat more of to keep it in top-top condition? But before we talk about specific gut-friendly foods, first let’s understand more about the connection between gut health and the immune system.

What’s the connection between gut health & immunity?

Did you know about 70% of your immune system is within your 9-metre-long digestive system?1 This is partly down to a diverse community of trillions of gut bacteria living in your gastrointestinal (GI) tract. These microbes not only help with your digestive health, they also influence your overall wellness. Because your immune system and digestive system are so interconnected, problems in your gut could also make you more susceptible to feeling run down or picking up other illnesses. It’s not an easy link to get your head around. But the simplest way to think of it is that a healthy gut supports the immune system by preventing the infiltration of pathogens (or germs) into the body.

A simple breakdown of how gut health and immunity interact

  • A healthy digestive tract allows microscopic particles of digested food and nutrients to pass through the gut wall. But with the right balance of bacteria, it can also keep out larger food particles and pathogens.
  • If conditions within the GI tract aren’t optimal, the gut wall could be damaged. This allows large food particles and pathogens to escape into the rest of the body.
  • When ‘invader’ particles permeate the gut wall, it triggers an immune system response. This includes pain and inflammation in the gut. But it can also affect other parts of the body too.2

Foods to support immune system function

A healthy digestive system is essential to support normal immune system function. The immune system needs certain nutrients to work effectively and to defend your body against pathogens. So, what gut-friendly foods should you eat?

Probiotics to boost the balance of good bacteria in the gut

Probiotics are well known for aiding digestion problems, such as bloating and constipation, and for helping reduce IBS symptoms. But what is less recognised, is the role a healthy supply of good bacteria has in supporting immune system function. Friendly bacteria are important in the formation of a healthy gut wall. This strengthens the barrier that’s protecting your immune system from pathogen invaders. By helping prevent the growth and proliferation of harmful bacteria in the gut, probiotics are an important way to keep your gut microbiome healthy.3 Probiotics come in the form of live bacteria and yeasts. They are found in certain types of food – for example, cultured dairy products and unpasteurised fermented foods. They also come in the form of supplements.

You also need to feed good bacteria with prebiotics

Prebiotic foods help to feed a growing population of good probiotic bacteria breeding in your gut. That’s right, if you want probiotics to do their job, you need to nourish them. Prebiotics are non-digestible food ingredients that can fuel helpful bacteria. They are most commonly found in some fibre-rich foods. For example, onions, garlic, leek, Jerusalem artichokes, asparagus, bananas and jackfruit are all good prebiotic food stuffs. There are also prebiotic supplements that can help drive the growth of good bacteria.

And keep the bad stuff moving out with fibre-rich foods

Fibre helps to keep your digestive system healthy by encouraging regular bowel movement. It’s also a good source of prebiotics for the good bacteria in your gut to feed off. However, it’s important not to go overboard with your fibre consumption as this can lead to negative effects on your gut health. The NHS advises a daily intake of around 30g.4 Whole grains, fruit, vegetables, nuts and seeds are all good natural food sources.

Increase your fluid intake

Proper hydration is crucial to good gut health and supporting a stronger immune system. For example, increasing fibre and not increasing water intake can worsen constipation. This is because water helps fibre to pass through the digestive tract. The NHS Eatwell Guide recommends 6 to 8 glasses of fluid a day as a guide.5


This more collaborative relationship between the digestive and the immune systems, is a relatively new discovery in the last decade. Although studies are now uncovering more about this connection, there’s a lot more to uncover. But with so much of the immune system located in the gut, there seems to be little doubt that what we eat can have an influence on our overall wellness, as well as digestive health.6 Last updated: 6 July 2020 Sourceshttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2515351https://provenprobiotics.co.uk/your-gut-as-your-immune-system/https://provenprobiotics.co.uk/your-gut-as-your-immune-system/https://www.nhs.uk/live-well/eat-well/how-to-get-more-fibre-into-your-diet/https://www.nhs.uk/live-well/eat-well/the-eatwell-guide/https://www.newsweek.com/gut-bacteria-immune-system-probiotics-1333541
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