How your gut and immune system are connected

Girl with headache

The immune system is the body’s in-built protection against pathogens and illnesses – organisms like bacteria, viruses and other microbes that can cause sickness and disease. The gut is the first line of the immune system. Besides playing a major role in digestion and absorption, the gut acts as a physical barrier preventing pathogens from entering our internal system. The gut also hosts a complex system of microbiome communities, particularly in the colon.

What is the microbiome?

‍The microbiome is a collection of trillions of microbes (mostly bacteria) living in or on the human body – ideally in harmony. There’s been increasing evidence recently to suggest there’s a lot of interaction between the body’s immune system and the bacteria in your gut. This connection is based on the fact that a large proportion of your immune system is actually located within the lining of the gut barrier. The gut microbiome has been shown to influence immune functions both within the gut and other parts of the body.

Your environment, food intake and certain health conditions, including diabetes, heart disease and obesity, have a direct impact on the gut microbiome community balance and diversity. Similarly, an impaired gut barrier, which causes increased intestinal permeability – what’s known as a ‘leaky gut’ – contributes to the transfer of harmful pathogens into our internal system, causing inflammation. If this intestinal barrier goes unrepaired, it may lead to a continuous inflammatory response capable of triggering autoimmune processes, which increases your risk of developing chronic diseases later in life.

Supporting and maintaining a healthy gut microbiome, and achieving good gut health, begins with what you eat.

Eating a healthy, varied diet will help you get all the nutrients you need and support a healthy gut microbiome. This means eating from all the food groups each day, including dietary fibre, probiotics and prebiotics, as well as drinking plenty of water and maintaining a healthy lifestyle that includes regular exercise.

The difference between probiotics and prebiotics

‍Probiotics are the live microbes – or good and friendly bacteria – that makeup part of our microbiome and provide health benefits. They work by restoring the natural balance of the gut microbiome. The best sources of probiotics are yoghurt, kefir and fermented foods such as kimchi, sauerkraut and miso.

Prebiotics are undigested dietary fibres that feed the healthy microbes living in our gut. The best sources of prebiotics are vegetables, fruits, cereals, grains and nuts.

Why is a healthy gut microbiome so important?

Dysfunction of either the gut and/or immune system may compromise your health. Benefits of a healthy gut microbiome include:

  • improved digestion
  • improved ability to absorb nutrients from food
  • reduced risk of infection
  • boosted immune system and gut barrier
  • improved general health and wellbeing.

Eating a varied and healthy diet together with leading a healthy and active lifestyle, which includes lowering stress and sleeping better, will help to improve and support a healthy gut microbiome and can boost your immune system.

Dr Cuong TranThis article was written by Dr Cuong Tran

Dr Cuong D Tran is a senior research scientist and at team leader at CSIRO Health and Biosecurity Business Unit in the Food and Nutrition Program, and an affiliate senior lecturer at the University of Adelaide. He has a PhD in nutritional physiology and gastroenterology, and more than 15 years research experience in gut health and nutrition, and gut disorders and well-being in paediatrics and adults. Dr Tran has a research interest in gut barrier function and microbiome, particularly developing effective measures of gut health and function and how that impacts overall health and well-being. He has published over 50 peer-reviewed research papers ranging in topics including gut microbiome and health, zinc nutrition as a potential therapy for inflamed conditions of the gut, non-invasive testing for gut health and small bowel integrity and function.