Gut health and the secret to a healthy immune system

Your gut is responsible for absorbing the nutrients from your food. It is also linked to the production of neurotransmitters for supporting your mood as well as a healthy immune response.

A busy lifestyle can trigger stress hormones that affect your digestion 

Slow digestion | Loss of appetite | Irregular bowel movements | Compromised nutrient absorption | Digestive imbalances | Upset stomach


Gut disturbance can have a profound effect 

Poor energy levels | Mood imbalance | Disrupted sleep patterns | Lowered immune function

Gastrointestinal Distress

Your gut microbiome forms the foundation for your general health and wellbeing. Often when you are experiencing a lack of energy, sleeping problem, mood concerns, compromised immune system function or concerns with your joints and skin, it can be traced back to the health and function of your digestive tract.

It is important to support your digestion and liver function because when you digest and detox efficiently, you are better able to absorb nutrients and produce healthy levels of mood neurotransmitters like serotonin to lift your mood, melatonin to support your sleep, and manufacture healthy immune cells for a healthy immune response.

Recently, Chinese scientists have found a link between gut bacteria diversity and your risk of developing long COVID. University of Hong Kong researchers found patients with long COVID has a less diverse and abundant gut microbiome.

The study, published in the BMJ Gut, involved analysing the faecal microbiome of patients, with varying degrees of disease severity, and controls who didn’t have COVID. At six months, 76 per cent of patients had long COVID or post-acute COVID-19 (PAC), with fatigue, poor memory and hair loss being the most common symptoms.

Long-COVID patients’ gut bacteria less diverse

The patients with PAC had lower diversity and richness of bacteria, on admission to hospital and at a six-month faecal analysis, when compared patients who didn’t have COVID and those who had fully recovered, the study says.


The long COVID patients had fewer ‘friendly’ bacteria and more ‘unfriendly’ bacteria than COVID-19-free people, the researchers say.


Researchers also identified bacterial species linked to specific long-COVID symptoms. For example, respiratory symptoms were linked with ‘unfriendly’ microbes, including Streptococcus anginosusStreptococcus vestibularisStreptococcus gordonii and Clostridium disporicum.

Study limitations

This study was however, a relatively small study, involving 106 COVID patients and 68 non COVID patients, and it also doesn’t establish causation. As an observational study it just shows an association.

5 ways to diversify your gut microbiome

There are simple diet changes you can make to increase the abundance of ‘friendly’ gut bacteria you have and decrease the volume of more problematic bacteria.

1. Eat plenty of plant foods and focus on variety.

Studies have shown eating mostly vegetables, fruit, legumes and whole grains is linked to a higher abundance of gut bacteria. Aim to eat a wide variety of around 30 different plant foods over a week to get the best results.

2. Eat all three types of fibre

Fibre provides food for your gut bacteria. There are three types and it’s important to consume them all.

    • Insoluble fibre is found in wholegrain flour, bread and cereals, fruit and vegetable skins and nuts
    • Soluble fibre is found in oats, seeds legumes, barley and vegetable and fruit flesh
    • Resistant starch found in slightly unripe bananas, beans, peas, cooked and cooled pasta, rice or potatoes, and uncooked rolled oats

3. Enjoy fermented foods

Consume some of the following every day to benefit your gut microbiome: yoghurt, sourdough bread, cheese, kombucha, kefir, kimchi sauerkraut, tempeh and miso.

4. Limit alcohol

Alcohol can increase the growth of bacteria that potentially increase toxins in the gut. Alcohol can also increase leaky gut and inflammation.

5. Get your omega-3s

Regular consumption of omega 3-rich oily fish has been shown to encourage inflammation-fighting gut bacteria. If you don’t eat fish, you can get omega 3 from plant sources, including canola, flaxseed and soy oils, tofu, walnuts, pumpkin seeds and some green vegetables.

If you are interested in knowing more about gut health and how it affects your immune system, contact me. As a qualified nutritionist, I’m happy to answer any questions you may have


  • Healthy Food Guide. (2021, April 15). A plant-rich diet may help your gut bacteria fight disease.
  • Liu, Q., Mak, J. W. Y., Su, Q., Yeoh, Y. K., Lui, G. C.-Y., Ng, S. S. S., Zhang, F., Li, A. Y. L., Lu, W., Hui, D. S.-C., Chan, P. K., Chan, F. K. L., & Ng, S. C. (2022). Gut microbiota dynamics in a prospective cohort of patients with post-acute COVID-19 syndrome. Gut, 71(3), 544.
  • Purohit, V., Bode, J. C., Bode, C., Brenner, D. A., Choudhry, M. A., Hamilton, F., Kang, Y. J., Keshavarzian, A., Rao, R., Sartor, R. B., Swanson, C., & Turner, J. R. (2008). Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: Summary of a symposium. Alcohol (Fayetteville, N.Y.), 42(5), 349–361.

 Bachelor of Science (Biochemistry and Biological Science) University of Canterbury

   Graduate Diploma Human Nutrition, Ara Institute of Canterbury

   Member of the Nutrition Society of New Zealand, Associate Registered Nutritionist