Our body is full of bacteria – a fact that almost never fails to conjure images of disease and illness, but always leaves less of an impact than it should, considering the immense role these bacteria play in our health.

We’re about to explore just how much both probiotics (the bacteria and other microorganisms that benefit our health, which also exist in various foods) and prebiotics (the foods that help these bacteria flourish) can help our body.


Bacteria’s Role in Our Gut

Our gastrointestinal tract (GIT) performs some crucial functions like:

  • Providing the body with nutrients, after breaking down the food we eat
  • Preventing harmful substances from being absorbed
  • Getting rid of waste

We have over 100 trillion bacteria – of about 1000 different types – in the GIT. The fact that these bacteria help the GIT in going about its tasks isn’t recent news. Today, however, the microbes in the lower GIT (the “gut”) are actually being referred to as an organ in themselves, because of their own distinctive and unique metabolic purposes.1

All of these stem from their fundamental function of fermenting dietary fibre that hasn’t been digested.This goes on to have several consequential effects in the body –

1) The fermentation provides energy to both the bacteria and the body, resulting in less food being required by the body (potentially leading to weight loss).2

2) It creates a substance called ‘butyrate’, which prevents diseases of the digestive track (like ulcerative colitis, Crohn’s disease, irritable bowel syndrome and even cancer). Butyrate is also believed to increase satiety, which reduces our appetite and curbs overeating.

3) The bacteria help the body absorb the magnesium, calcium and iron from the food we eat, and even produce some B-vitamins (like B12, biotin and folate). In fact, it’s the only source of B12 for vegans (and, apart from dairy, for vegetarians as well).3

4) The bacteria influence how quickly waste is excreted from the body.

5) They improve the quality and increase the quantity of bile produced by the liver (bile is the substance that digests fats in our small intestine).4 Since cholesterol gets used up in the making of bile, increasing the quantity of bile also reduces our blood cholesterol.5

As if this weren’t enough, these bacteria, amazingly, go on to do even more.


Other Roles of Good Bacteria

This is probably the most interesting part of probiotics: scientists believe that our immunity, skin, obesity and even mental state are all affected by the population of bacteria in our gut.

Let’s take a look at how.


1] Immunity:

We all eat both good and bad food. The invading microorganisms from these foods are first met by our GIT, which makes it our first line of defence.

Here, the gut bacteria stop harmful microbes from sticking to the lining of the GIT, and also neutralise certain chemicals, preventing toxins and other substances that came with the food from passing into our blood.

Interestingly, this process starts from the minute a baby is born. The bacteria from the mother’s birth canal are transferred to her child, where they start growing. Since they control what kind of bacteria are allowed to enter the child’s body, they indirectly determine how his or her immune system develops and adapts, affecting the kind of infections they get – and even playing a role in allergies. (Many baby formula brands are probiotic-enriched these days, to speed up the development of the gut bacteria in formula-fed babies)6-8

There’s a constant interaction between our immune system and the GIT bacteria throughout our life, via many processes.

What’s startling is that our immune system – which we think is designed to control microorganisms – may in fact be controlled by microorganisms. It’s simply a battle between the good and bad.


2] Skin and Mental Health:

You must have heard that we even have bacteria living on our skin. These help the skin by maintaining its health and helping wounds heal.

Even the bacteria in the gut can affect our skin, though, since they prevent toxins from passing into our bloodstream. When there are fewer numbers of these good bacteria, toxins are able to enter the bloodstream and reach other parts of the body, causing inflammation on the skin, which can result in skin issues like dermatitis and acne.

This similarly affects the way our brain functions (including the way we handle stress), and the production of our hormones – that’s actually the reason stressful times are usually accompanied by skin issues. This fascinating phenomenon is called the gut-brain-skin axis.9-12


3] Obesity:

The scientific community has known for many years now that our gut bacteria, because of the substances they produce, can affect our feeding behaviour.

What has only recently been discovered, however, is just how much they also affect obesity.

Studies have shown that transferring an obese mouse’s gut bacteria into the gut of a lean mouse makes the lean mouse obese as well (and vice-versa). This is believed to apply to humans, too, because the bacterial composition of the gut isn’t the same in lean and obese humans, based on dietary factors.13

Obesity is also a result of many processes gone wrong – right from the way our body uses glucose, to the way calories are burned during any activity. This makes it closely connected to other conditions like inflammation, type-II diabetes and metabolic syndrome. The crosstalk between the gut bacteria and organs like the liver, fat tissue, muscles and the brain can play a crucial role in harmonising these processes.

Since this discovery, probiotics have garnered a lot of attention when it comes to beating obesity, and improving overall health.14, 15

You can read further on this subject by getting a list of foods that can boost this inner ecosystem, for all the benefits of a healthy gut, right here.



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3. LeBlanc JG, et al. Current opinion in biotechnology 2013, 24(2): 160-168.
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5. Dikkers A, Tietge UJF. World Journal of Gastroenterology : WJG 2010, 16(47): 5936-5945.
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7. Challa S, Quigley EMM. Probiotics For Dummies. Wiley, 2012.
8. Jakobsson HE, et al. Gut 2014, 63(4): 559-566.
9. Bowe WP, Logan AC. Gut Pathogens 2011, 3: 1-1.
10. Arck P, et al. Experimental dermatology 2010, 19(5): 401-405.
11. Foster JA, McVey Neufeld K-A. Trends in Neurosciences 2013, 36(5): 305-312.
12. Holzer P, Farzi A. Advances in experimental medicine and biology 2014, 817: 195-219.
13. DiBaise JK, et al. Am J Gastroenterol Suppl 2012, 1(1): 22-27.
14. Geurts L, et al. Benef Microbes 2014, 5(1): 3-17.
15. Le Barz M, et al. Diabetes & Metabolism Journal 2015, 39(4): 291-303.

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