How the state of our gut microbiota affects our overall health 

Gianfranco Grompone

Our Chief Scientist, Gianfranco Grompone, likes to remind people that we are all really just walking microbial ecosystems, full of microorganisms living in and on our bodies. 

He’s right of course. Your body is home to many trillion microorganisms, including 38 trillion bacteria. All together, the bacteria in your body weigh around 2 kg. 

Not too long ago, it was thought that bacteria were all bad, that they only caused infections and disease. Today we know that the vast majority of bacteria are either harmless or actually beneficial to our health, and some of them are absolutely essential to our survival. Only a handful pose a pathogenic threat (meaning that they are potentially harmful) to humans.


Together, all the microorganisms in your body, including bacteria, yeast, fungi, viruses and parasites, make up your microbiota. And this community of microorganisms (ie, all the microorganisms that can usually be found living together in any given habitat), and their “theatre of activity” (ie, not just that they are there, but also how they coexist and function together) is what we mean by the term microbiome

Approximately 90-95% of these microorganisms can be found in our gastrointestinal tract, or what we commonly call our gut. The gut flora, or microbiota, consists of trillions of bacteria belonging to thousands of different species. 

Benefits of Microbiota
● Digest food and absorb nutrients 
● Regulate, support and educate the immune system 
● Fight off harmful bacteria 
● Produce vitamins and other important substances 
● Break down toxins from drugs or other sources 

The gut flora may even affect the brain and therefore our moods. 

BioGaia’s L. reuteri

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BioGaia’s probiotic products with Limosilactobacillus reuteri formerly known as Lactobacillus reuteri are among the most scientifically well-documented probiotics in the world.

Where do our gut microbiota come from?

Infants establish their gut microbiota at birth and through the first three years of life. Babies are almost completely sterile at birth, but immediately thereafter bacteria start to colonise their mouth, their skin, their gastrointestinal tract and every other part of their body. 

The first and most important factor affecting a baby’s microbiota is how they are born. Babies born vaginally acquire bacteria directly from their mothers as they pass through the birth canal. Whereas babies born via caesarean section primarily pick up bacteria from their mothers’ skin and the hospital environment, and they tend to have less beneficial bacteria overall in the first important days and weeks of life. 

After birth, breastfeeding, bottle-feeding with expressed breastmilk, and/or formula-feeding are the second major factor affecting the baby’s microbiota. Breastfed babies have an abundance of bifidobacteria which consume oligosaccharides - special sugars that are found in breast milk and that can only be digested with the help of bifidobacteria. Other beneficial bacteria such as lactobacilli are passed on from mother to baby during breastfeeding. 

The amount and diversity of bacteria continue to increase until the age of three. After the age of three, the child’s microbiota is more stable and largely resembles the composition of an adult’s.

Health starts in the gut

Another thing Gianfranco (our Chief Scientist) likes to talk about is that “Health starts in the gut.” But what do we mean by this? 

You may have heard that 80% of your immune system is located in your gut. In fact, your gut, or gastrointestinal tract actually starts in your mouth and extends all the way through your oesophagus, to your stomach and small and large intestines. It is nine metres long and thanks to its 800-900 folds, it would cover half a tennis court if you laid it out flat. This makes your gut by far the largest contact surface your body has with the outside world and explains the importance your gut has for your immune system. 

The gut microbiome fulfils the dual roles of gatekeeper and personal trainer of the immune system, contributing to the mucus barrier that keeps pathogens out and teaches the immune system’s T-cells to recognise and destroy harmful entities. 

A balanced microbiota with enough good bacteria is important for a well-functioning immune system. The good bacteria educate the immune system and prepare it to fend off unwelcome invaders like bad bacteria and toxins. 

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BioGaia's products are sold in more than 100 countries all over the world through a large network of distributors.

What does it mean to have a balanced microbiota and what are the effects of an unbalanced gut?

In the most basic sense, the good bacteria in your gut need to outnumber the bad bacteria by twenty to one. If the bad bacteria in your gut start to become more numerous than the ten to one ratio, your digestive system may find itself in an imbalance called dysbiosis. 

An unbalanced gut can lead to a wide range of problems. Everything from stomach issues such as diarrhoea, constipation, bloating, temporary stomach pain and leaky gut, to skin problems, difficulty sleeping, problems with mental well-being and impaired resistance to infections. In addition, new research suggests a probable connection between gut health and diabetes, obesity and cardiovascular disease. 

What other connections are there between the gut and the rest of the body?

There is a lot of ongoing research about the connections between gut health and overall health, besides the studies mentioned above. Some extra exciting areas of study are around the gut-brain axis and the gut-skin axis. 

The gut-brain axis

It may sound far-fetched, but your gut and your brain are intimately connected and in constant dialogue with each other. Scientists are even referring to the gut as the second brain, which is also called the enteric nervous system (ENS). It’s made up of two thin layers of more than 100 million nerve cells all along the lining of your gastrointestinal tract. The connection between the gut and the brain means that the state of our gut microbiota can impact things like mood, mental health, appetite, behaviour and circadian rhythm. 

The gut-skin axis 

The gut-skin axis refers to the constant dialogue between your gut and your skin. The close connection between your gut and your skin means that the state of your gut may have an outsized effect on the state of your skin. 

That’s why checking in with the way your skin looks and feels can also be a good way to check in on the state of your gut. And when your skin isn’t looking its best, that could be a sign that the balance is off in your gut. 

How does lifestyle affect the gut flora?

Dramatic changes in lifestyles over the last 50 years have left their marks on the state of our gut. Increased urbanisation and new eating habits have resulted in negative changes to our microbiota. 

Our microbiota is negatively affected by: 

Antibiotics kill all bacteria, not only the harmful ones that cause illness and disease 

Showering several times a day, using germ-killing soaps and detergents etc, all deplete our microbiota 

Babies born by C-section don’t pass through the birth canal and are therefore not exposed to the desirable variety of good bacteria from their mother 

Fast food, processed food, coffee and alcohol. It may taste good, but your gut bacteria do not thrive on junk food, they need fibre, fresh fruits and vegetables 

Both stress and a lack of sleep may lead to changes in the composition of the gut bacteria and a reduction of microbial diversity

While working out is beneficial for your general well-being, professional athletes are often exercising at a level that harms their microbiota and puts their immune system under stress, making them more susceptible to infections.

On the flip side, we can also affect our gut health by maintaining a healthy lifestyle and doing things like: 

Eating a balanced and varied diet that includes lots of fruits and vegetables
Getting lots of restful sleep every night 
Moving our bodies every day, especially outside! 
Limiting stress and taking time to breath, stretch and practise mindfulness
● Taking a daily probiotic supplement

Good vs. Bad Bacteria

Good bacteria 

Good bacteria can be found in food. Long before we had refrigerators and freezers, people used bacteria in fermentation to prolong the shelf-life of food. Examples of fermented foods are yoghurt, sauerkraut and pickled vegetables. Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophilus, are all lactic acid bacteria commonly used for fermentation. 

Truly healthy bacteria are known as probiotics. Probiotics are live bacteria that are proven to benefit our health by restoring the bacteria balance in the body. They are usually consumed as food supplements. Examples of common probiotic strains are Limosilactobacillus reuteri Protectis, Lactobacillus rhamnosus GG and Bifidobacterium animalis ssp. lactis BB-12. 

Bad bacteria 

A small percentage of all bacteria on earth are pathogenic, meaning they may cause health problems and disease. Food poisoning may be caused by E. coli and Salmonella, sepsis by S. aureus and S. pneumoniae can give pneumonia. 

It is important to remember that bacteria of the same species but of different strains can behave completely differently. Some species, like E. coli, harbour strains that are extremely pathogenic, like EHEC and ETEC, which cause severe diarrhoea. On the other hand, some strains of E. coli are commensals, meaning that they are harmless to humans and they are one of the most common bacteria we carry in our gastrointestinal tract. 

Probiotics research

Research on bacteria and their significance for our health has exploded in the past decade. At BioGaia, we’ve spent the last 30 years doing clinical research on Limosilactobacillus reuteri


Read more about our research here.