I remember clearly the first time I went skiing. I was about 6 years old, and I was convinced that, as soon as I had my skis on, I would be able to ski down the slopes, just like all the other people around me. I mean how complicated could it be? You just have to let yourself slide down, right?

I put my skis on and started to move on the snow. Except that, instead of moving forwards, I slid backwards, lost my balance and fell. I was frustrated and furious. In my 6 years old mind, it wasn’t making sense. It looked so effortless and easy! I hadn’t learnt yet the importance of starting with the basics, the fundamentals (such as facing the slope the right way!) before being able to do the more complex things such as going down the hill.

When people are coming to see me, and they are unwell or exhausted, they are often looking for a quick fix for what is a complex problem. Just like me as a child, they are hoping that things will just fall into place all on their own. But they are missing the fact that they first need to work on the fundamentals such as their gut flora. In this article, we will look at:

    • What the gut flora is
    • Why feeding the gut flora is essential to your health
    • When you should look after your gut flora
    • How probiotics can help rebalance your gut flora

The gut flora, or gut microbiome, is the whole of the microorganisms living in the gut.

Gut bacteria and health

It’s a collection of bacteria, viruses, microbes, fungi all living in symbiosis with our gut. There are about 10-100 trillion microorganisms in the gut, outnumbering the human cells 150 to 1. There are mainly composed of bacteria (about 35000 different species!), but we still don’t know what all the different species populating our intestinal tract are (1).


Gut bacteria help the body digest and absorb nutrients.

The bacteria in our gut help digest carbohydrates and get energy out of what would otherwise be undigestible fibre. They also help absorb some compounds found in fruits, tea, cocoa or wine. Some bacteria also synthesize vitamin K as well as some B vitamins (2).

Gut bacteria supports the immune system.

The gut bacteria control how the immune system works. The bacteria communicate with immune cells and control how the body reacts to infection, through the innate and adaptive immune system (3) (4). They can influence how susceptible the body is to infections but also to auto-immunity, chronic inflammation or cancer.

Gut bacteria helps to keep the gut wall intact.

Gut bacteria help to maintain the structure and the function of the gastrointestinal tract. This is essential as an impaired tract has been associated with disease such as Crohn’s disease, some food intolerances (what is sometimes referred to as ‘the leaky gut’) or inflammatory bowel diseases (IBS and IBD) (5).

There is also a strong link between the brain and the gut bacteria.

The gut bacteria produce compounds that influence the nervous system as well as the production of neurotransmitters. These have an essential role in various disorders such as depression but are also associated with multiple sclerosis (MS), Parkinson’s disease, fibromyalgia or obesity (5).The brain also influences the gut bacteria, including on its diversity.

To stay healthy, you need to keep the balance in your gut just right.

In our gut, we have what are often called ‘good bacteria’ that are needed to stay healthy and some ‘bad bacteria’ which act as pathogens such as E. Coli and Campylobacter. It’s normal to find both of those in the gut. What is important is to keep the balance right with plenty of good bacteria to counterbalance (and keep in check) the pathogenic bacteria.

What we eat is crucial to keep the balance between ’good’ and ‘bad’ bacteria.

We know that what we eat plays a significant role in the composition of our gut microbiome, with some experiments showing that changing your diet can influence the gut flora within 24 hours (6)!

Some foods will encourage the development of certain bacteria whilst decreasing the presence of others. Vegetable proteins, proteins from meat, fats and carbohydrates all have a different influence on the gut flora. Fibre is particularly important to support gut bacteria.

Fibre is a prebiotic.

What we mean by that is that fibre is a non-digestible component of the food that stimulate the growth of certain microorganisms. Fibre helps support gut bacteria variety and abundance, which is essential to health. Sources of prebiotic fibre are:

Type of prebiotics


Beta-glucan Cereals such as oats and barleyMushrooms suh as Reishi, shiitake, maitakeSeaweedsAlgae
Inulin LeeksAsparagusOnionsWheatGarlicChicoryOatsSoybeansJerusalem artichokes
FOS (fructooligosaccharides) ChicoryOnionsAsparagusWheatTomatoesGarlicBananaArtichoke
GOS (galactooligosaccharides) Jerusalem artichokeLentilsBeansChickpeasOnion

Antibiotics also influence our gut flora.

Antibiotics are one of the most significant sources of imbalance of the gut flora. Because antibiotics have a broad spectrum, some bacteria in the gut is also killed by them (at the same time than the infection they are helping us fight). Different antibiotics will have a different effect on the gut flora. It usually takes 1-4 weeks for the gut flora to recover from antibiotic treatment, but some species do not recover quickly. Even two years after taking antibiotics, some species can still be missing and the level of recover varies from one individual to the next.

Several studies have linked recurring antibiotics treatments some illnesses such as asthma, obesity or type 1 diabetes showing the link between antibiotics and long-term health effect on the body.

Probiotics can help the gut flora recover from antibiotic treatment.

Probiotics are live organisms which, when ingested, confer some health benefit to the host (and in particular to its gut flora). They are usually bacteria (such as Lactobacillus) and might be beneficial to help restore gut flora balance. This means they could also be beneficial to someone after antibiotic treatment.


Probiotics and gut floraProbiotics can usually be found in fermented foods such as

  • Yoghurt
  • Kefir
  • Sauerkraut (raw)
  • Tempeh
  • Kimchi
  • Miso
  • Kombucha



But I hate sauerkraut and all those other foods!

I have to say this is not unusual. The real advantage of fermented foods is that they are providing the body with a range of friendly bacteria in their natural environment. You can add them in small quantities to the side of your dishes (e.g. with kimchi or sauerkraut). However, they are uncommon and require an acquired taste for them.

One way to solve that issue is to look at probiotics in ‘capsules’. The significant advantage is that they are much palatable. However, the type of strain in that supplement will be much more restricted (usually to a couple of strains) and might not be what you need. As different strains of bacteria have different effects on the body, I would recommend getting some advice from a nutritionist first, to find which probiotics are the most suitable for you.

Let’s recap.

The health of our gut flora is linked to our health. To ensure that our gut flora is abundant and varied, we need to take care of eating the right diet, in particular a wide variety of fibre to ‘feed’ the bacteria in our gut. Our gut flora is also affected by antibiotics. Probiotics can be one way to help repopulate our gut bacteria after antibiotic treatment.

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