In last week’s instalment of this series of articles on the gut flora mircobiome and its importance to health, we looked at its role in digestion, and how we are reliant on it in order to be able to absorb much of the energy and essential nutrients from our food.

Aiding digestion is only one side of our gut flora’s importance to our health, however, and it is its role in supporting our immune system and protecting us from both infectious and degenerative disease where gut flora really starts to become interesting.

Just as we are dependent upon our microbiome for our nutrition, they are equally, if not more, dependent upon us. To our gut flora, we are like giant combine harvesters, travelling around collecting food for them, before breaking it down into manageable pieces in our mouths and stomachs, ready for them to ferment.

If something were to happen to us, like become ill, or worse yet die, it would quite literally be the end of the world for our gut flora!

It is therefore no surprise that we have evolved in such a way that our microbiome works with our immune system to help protect us from illness and disease.

Immunosensory detection of intestinal bacteria. Hara and Shanahan 2006

Though it is likely that science is only really scratching the surface, recent research has found a number of ways in which friendly bacteria help protect us from both infection from other, pathogenic microbes, and degenerative diseases such as cancer and metabolic dysfunction.

1) Safety in Numbers

The most basic way your microbiome protects you from infection from pathogenic microbes is simply through safety in numbers. We should be reasonably well stocked with beneficial bacteria from birth, and then further topped up through breast milk (More on this in an upcoming post). Once your gut microbiome is established, they take up all the room and all the resources, so that if any invaders try to make home in your intestines, they simply can’t get established.

2) Chemical Warfare

Solidarity is not always sufficient to keep out the bad guys, but thankfully your good bacteria are not meek little defenseless organisms, and will defend their territory at all costs. Your gut flora actually produce their own antimicrobial chemicals which will kill pathogens, while leaving beneficial microbes unharmed.

3) Forming Allied Forces

In much the same way that your gut flora influence the development of your intestinal walls digestive capabilities, they also help modulate, develop and enhance your immune system. Not only do your gut flora physically strengthen the intestinal barrier and mucosal lining and maintain the tight-junctions which control what is allowed to pass through from your gut into your blood stream, but they actually communicate with your immune system, making it better able to identify pathogenic microbes and destroy them.

4) Cancer Fighting Properties?

Although the exact mechanisms are not yet known, it seems that risk for colorectal cancer is greatly reduced in individuals that have a healthy population of friendly gut flora. There is also evidence that consuming lactic acid producing bacteria can prevent carcinogen induced lesions and tumours!

Hopefully, these introductory posts into the essential roles of beneficial gut microbes in human digestion and immunity have conveyed the importance of having a strong and healthy population of gut flora.

The second half of the series will be looking at what happens if your good gut flora become diminished, displaced or destroyed, why antibiotics should always be a last resort and could even lead to serious illness, and finally, how to look after, repair and replenish your microbiome to restore your body to optimal health.

Below are links to some full text resources if you’re interested to learn more about the mechanisms by which gut microbes interact with their host symbiotically:

Gut microbiota: next frontier in understanding human health and development of biotherapeutics

Satya Prakash, Laetitia Rodes, Michael Coussa-Charley, and Catherine Tomaro-Duchesneau (2011)

The gut flora as a forgotten organ

Ann M O’Hara1 and Fergus Shanahan (2006)

Gut Microbiota, Immunity, and Disease: A Complex Relationship

Michele M. Kosiewicz, Arin L. Zirnheld, and Pascale Alard (2011)

Thanks for reading, I hope you found this post of interest. I would love to hear your thoughts and comments below, or feel free to tweet me at @Simon_Whyatt

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