The Gut-Immune Connection

What We Know So Far

Immunity has been at the forefront of our minds for the past few years now and traditionally we have often associated it with a few key nutrients namely: Vitamins A, C and D and minerals such as magnesium, iron and zinc. However, in light of recent times we’re starting to understand more about the role of the gut microbiome on the immune system. Around 70% of the immune cells are located inside the gut microbiome. This microbiome is a collection of bacteria, viruses, pathogens and fungi – some of which can be hugely beneficial to our health and others less so.

Evidence has associated a stronger immune function with a more diverse gut microbiome and one rich in commensal bacteria (good bacteria). The gut and the immune system have a strong method of communication which is key to our existence as this allows the gut to alert the immune cells of any unwanted pathogens which in turn stimulates the immune cells to attack these pathogens and prevent them passing through into the rest of the body.

The intestinal barrier is particularly important for the health of the immune system as it can prevent unwanted pathogens passing into the blood and circulating around the body. Therefore, ensuring a strong intestinal barrier is really important in supporting the immune system.

The first 1000 days of live (including the time in the womb) have been shown to have the greatest impact in shaping the gut microbiome and that a more diverse gut microbiome is associated with a reduction in autoimmune conditions such as eczema, asthma and psoriasis to name just a few. However, this does not mean that we cannot change our gut microbiome following this period it simply states the importance of our early years on health outcomes later on in life.

Additionally, evidence has shown that consuming a diet rich in fibre and fermented foods can help to diversify the gut microbiome and contribute to reduced inflammation in the body.

With that in mind, below are some top tips for supporting the immune system:

  • Consume a diet rich in polyphenols – polyphenols are chemical compounds found naturally in plants and have antioxidative and anti-inflammatory affects. Sources of polyphenols include: dark chocolate, berries, nuts and soy beans.
  • Ensure adequate amounts of Vitamin C – hitting your 5-a-day will provide you with ample amounts of Vitamin C as fruits and vegetables are the best sources.
  • Consume plenty of fibre rich foods – high fibre foods help to diversify the gut microbiome which has been associated with a stronger immune system. Fibre rich foods include: wholegrains, nuts, seeds, fruits, vegetables, beans and pulses.
  • Aim for one source of fermented foods per day – fermented foods increase the good bacteria in the gut. These include: yoghurt, kimchi, sourdough bread, kefir and kombucha too.

Everyone’s gut health and immune function is unique so remember to take things slowly and find out what works best for you. Additionally, if you have an auto-immune condition please always seek personalised advice.


Mukhopadhya, I., Segal, J. P., Carding, S. R., Hart, A. L., & Hold, G. L. (2019). The gut virome: the ‘missing link’ between gut bacteria and host immunity?. Therapeutic advances in gastroenterology12, 1756284819836620.

González Olmo, B. M., Butler, M. J., & Barrientos, R. M. (2021). Evolution of the human diet and its impact on gut microbiota, immune responses, and brain health. Nutrients13(1), 196.