Impact of the Gut Microbiome

Question 1

What dietary factors affect immune health?

Answer 1

Good nutrition is essential for overall good health, with diet to support immune function being a fairly central component.
In cases where time, resources or skills prevent a good diet, or where there is a clear case of illness provoked by nutritional deficiency, specific supplementation over the short term could be helpful
Identifying and recommending appropriate supplementation however is only part of the picture of nutrition as it relates to immune function.
If absorption or assimilation of nutrients is pathologically impaired then no
amount of supplements will address this.

Question 2

What is the gut microbiome?

Answer 2

• More than a trillion microbes live within our gastrointestinal tract, the majority of which are
  innocuous or beneficial.
• They are responsible for vital metabolic, immune and nutritional
  functions. It would be erroneous to label them ‘gut bacteria’ as there is a dazzling array of
  organisms that constitute the microbiome of the gut, including viruses and fungi.
• Dysbiosis, when the microbiome becomes pathologically imbalanced, is associated with many common diseases.
• This quotation from Sidhu and Poorten’s paper eloquently summarises the role of the microbiome in the immune function of the human body:

‘Normal gut microbiota are our first internal line of defence against pathogens and toxins, protecting the body against disease in tandem with the host immune system.

One of the key functions of a healthy microbiome is to prevent colonisation of pathogens through a barrier effect. This occurs through the production of antimicrobial compounds such as bacteriocin and the outcompeting of pathogens for nutrients and attachment sites through sheer force of numbers.
Gut bacteria are also
integral to the development of the mucosal innate immune system through direct interactions with intestinal epithelial cells. Early exposure to a variety of bacteria provides a kind of training for the immune system such that normal protective responses occur to commensals and appropriate
inflammatory responses occur with exposure to pathogens.
Conversely, reduced microbial diversity and exposure early in life can lead to an immune system that over-reacts to antigens, predisposing to autoimmune and allergic disease’ Sidhu, M. and van der Poorten, D., 2017. The gut microbiome.
Australian family physician, 46(4), pp.206-211.

Question 3

What happens when the gut microbiome goes wrong?

Answer 3

The imbalance may arise broadly from two pathways – either overgrowth of non-beneficial
organisms or damage to beneficial ones.
* Factors which can promote dysbiosis: * Excessive intake of refined carbohydrates and sugars, literally ‘feeding the weeds’
* Excessive intake of alcohol – two damaging factors arise here, the first is that alcohol provides more unwanted sugar and the second is the inflammatory effect on the gut lining making the tissues less able to support the microorganisms of the microbiome
* High levels of stress – the promotion of cortisol caused by stress also has directly inflammatory effects on the gut
* Exposure to refined additives and inorganic chemicals

Possible clinical indicators of dysbiosis:
* Diarrhoea, fatigue, constipation. joint pain, bloating, halitosis (bad breath), nausea, a generally ‘upset stomach’

Conditions linked to a predisposition to
developing dysbiosis: IBS, Obesity, Certain neurological conditions, Cancers, Diabetes