• tanellewestgard

the why behind probiotics

Probiotics... most of us know that they consist of the so called "good" bacteria but what do they really do and how can they really help us? I find it is easier to take supplements when you understand how they are working and what they actually do in your body, which is what I am going to explain in detail below.

To understand probiotics, we first have to understand our gut-microbiome.

Part 1: gut

Did you know that our gastrointestinal tract contains about 80% of our immune system? And that about 60% of our hormones involve our gut too? The gut even has it’s own nervous system (that talks to our brain) called our enteric nervous system (1).

Beyond digestion, our gut plays a role in (1):

  • immune function

  • metabolism

  • detoxification

  • brain function ~did you know that more than 90% of serotonin is made in the gut?~

  • hormones

  • and many many more

Pretty impressive hey?

Okay, so now we understand how important the gut is.

Part 2: microbiome

Our microbiome is made up of microbiota – the bacteria (and viruses, fungi and protozoa) that live within us. This microbiome is on our skin, in our mouth, gut, genito-urinary tract and more. There are specific microbiota strains depending on where they are meant to be located in the body (1). For example, the microbiota on the skin are different from the microbiota in the gut, or in the genito-urinary tract. All together, these microbiota living in, on and around us have more genes than us humans do – and their genes make up our microbiome (1). A healthy and balanced microbiome (more good bacteria than bad bacteria) is crucial to our gut health.

How can bacteria be good you may ask?

It is said that we need our microbiome to not only thrive but survive (1). These bacteria in our gut are symbiotic with us, meaning we both benefit from each other. Most of us hear bacteria and freak out. When really... these symbiotic bacteria work alongside our immune system to protect us from the bad bacteria we are so scared of (as well as many many other functions).

So... just how much of these microbiota are in our body?

  • 3.3 pounds!!(1) = the equivalent of a large avocado

How about in the gut?

  • Over 100,000 billion, yes billion, microbes in the intestine alone (1).

For the remainder of this post, when I refer to our microbiome I am referring to the bacteria that live in our gut.

So now we understand two things:

  1. Our gut is incredibly important to our well-being – not only digestion but our immune system, hormones, and our brain.

  2. Our gut has an incredibly large microbiome with microbiota (>100,000 billion of them) that are important to our gut function and therefore all of #1.

Sometimes our microbiome can become out of balance. This causes our gut to become out of balance. Meaning that the bacteria present in our gut isn't the "good" kind OR we don't have enough of the "good" kind.

Causes of this include (1):

  • antibiotics

  • inflammation

  • stress!!!

  • infections

  • poor diet

This is where probiotics come in:

The theory is that if we provide our body with specific probiotics and deliver them to the area (in this case the gut) we can try to increase the number of good bacteria. By doing so, we can rebalance our microbiome (more good bacteria than bad bacteria) and restore our health (1).

Sounds pretty cool, right!?

Here is some research on it:

For many reasons (including allergens, inflammation, environmental triggers and long distance running) we can end up with something called leaky gut (1). Normally, our gut has these tight-junctions that are meant to selectively allow or prevent things from passing through. This includes preventing: bacteria, toxins, and antigens from passing through (2,3). If our gut is not able to prevent their passing, we end up with a "leaky gut" (increased gut permeability).

Research has shown that increased leakiness has been connected to (1,2,3,4,5):

  • Digestive conditions: IBS and gut ulcers

  • Immune health (colds and flus)

  • Atopic eczema

  • Allergies

  • Joint health

  • Depressive mood symptoms

  • Autoimmune conditions

Our microbiome is a protective factor that can regulate and protect our gut barrier to prevent leakiness (2, 4). These microbiota cling on to our gut lining and provide an extra layer that prevents things from passing. Research is aiming to show that by taking probiotics we can prevent leakiness and furthermore prevent some of the conditions that accompany it as shown above.

What else does our microbiome play a role in? (1,5)

  • athletic performance

  • weight loss

Are you as surprised as I was?

~this topic will make its own post~

As you can see, our microbiome plays a HUGE role in our overall health and this is why probiotics have become such a huge market.

This is just an intro post, I can’t wait to dive further into the intricacies and relationships of our microbiome at a later date xo

Post inspired by my attendance at : Atrium Innovations One Day Intensive on The Gut-Microbiome Impact on Female Hormone Health, Mood, Metabolism and Immune Function

presented by Dr. Nigel Plummer & Dr. Felice Gersh.


1) Plummer, N. T. (2019). The Microbiome. Atrium Innovations Seminar.

2) Mu, Q., Kirby, J., Reilly, C. M., & Luo, X. M. (2017). Leaky gut as a danger signal for autoimmune diseases. Frontiers in immunology, 8, 598.

3) Michielan, A., & D’Incà, R. (2015). Intestinal permeability in inflammatory bowel disease: pathogenesis, clinical evaluation, and therapy of leaky gut. Mediators of inflammation, 2015.

4) Ukena, S. N., Singh, A., Dringenberg, U., Engelhardt, R., Seidler, U., Hansen, W., ... & Suerbaum, S. (2007). Probiotic Escherichia coli Nissle 1917 inhibits leaky gut by enhancing mucosal integrity. PloS one, 2(12), e1308.

5) Bull, M. J., & Plummer, N. T. (2014). Part 1: The human gut microbiome in health and disease. Integrative Medicine: A Clinician's Journal, 13(6), 17.

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