How Our Gut Bacteria Affect Our Health

Our body is full of bacteria. 

Did that instantly conjure images of disease and illness? If so, you’ll be relieved to know that there’s a lot more to the microorganisms than that. In fact, the bacteria that live in us, especially our good gut bacteria, can actually play an immensely helpful role in our health.

In this article, we’ll explore how our gut bacteria affect our health, along with what we can do to use that to our advantage. 

Let’s start with:

Bacteria’s Role in Our Gut

Our Gastrointestinal Tract (GIT) performs some crucial functions like providing the whole body with nutrients, after breaking down the food we eat. It also prevents harmful substances from being absorbed, while getting rid of the body’s waste [1].

We have over 100 trillion bacteria – of about 1000 different types – in the GIT [2].

It’s well known that these bacteria help our GIT in going about its tasks. In fact, their contribution is so significant that, today, the microbes in the lower GIT (the “gut”) are being referred to as an organ in themselves, because of their own distinctive and unique metabolic purposes [3, 4].

All of these stem from their fundamental function: fermenting dietary fibre that hasn’t been digested. This goes on to have several consequential effects in the body [5]:

• The fermentation provides energy to both the bacteria and the body, resulting in less food being required by the body.
• It creates a substance called ‘butyrate’, which prevents diseases of the digestive tract (like ulcerative colitis, Crohn’s disease, irritable bowel syndrome, and even cancer). 

Apart from this, our gut bacteria also help us in other ways:

• Our gut bacteria may increase the bioavailability of folic acid, B12, and iron, and also produce vitamin K and some B-vitamins [6, 7].
• They influence how quickly waste is excreted from the body [8, 9].
• They improve the quality and increase the quantity of the bile produced by our liver (bile is the substance that digests fats) [10]. Since cholesterol gets used up in the making of bile, increasing the quantity of bile also reduces our blood cholesterol [11, 12].

This isn’t it, though. These bacteria, amazingly, go on to do even more.

The Roles of Good Bacteria Beyond the Gut

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.

Here’s how:

1. Immunity

We all eat both “good” and “bad” food. The bad can often come with invading microorganisms, which are first met by our GIT.

This makes the GIT our first line of defence against potential harmful microbes. The gut bacteria that live there stop harmful microbes from sticking to the lining of the GIT, and also, prevent toxins and other substances (that came with the food) from passing into our blood [12, 13, 14].

Interestingly, this process starts from the moment a baby is born. The bacteria from the mother’s birth canal are transferred to her child. Since they control what kind of bacteria can enter the child’s body, the mother’s gut bacteria indirectly determine how the baby’s immune system develops and adapts. This affects the kind of infections they get and even play a role in allergies [15, 16]. (Today, many baby formula brands are probiotic-enriched, to speed up the development of the gut bacteria in formula-fed babies) [16].

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 [15, 17], It’s simply a battle between the good and bad species of bacteria.

2. Skin Health

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

Even the bacteria in our gut can affect our skin, 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 which can result in skin issues like dermatitis and acne [18].

3. Mental Health

Increasingly, research has indicated that our gut ‘microbiota’ (the overall composition of the microorganisms in our gut) can help regulate our brain function through something called the “gut-brain axis” [19].

This axis refers to the fact that our brain and our gut have a strong connection that works both ways. They send signals to one another, which can directly affect their functioning [20, 21]. For example, the mere thought of eating can lead to our stomach releasing gastric juices even before any food enters the system [22].

It’s no wonder that ‘dysbiosis’ (when the diversity of this composition gets compromised) and inflammation of the gut have been linked to several mental illnesses, including anxiety and depression, which are prevalent in society today [23].

Recent research suggests that these could be treated by regulating our intestinal microbiota (through measures like consuming probiotics).

4. Obesity

The scientific community has known for many years now that, because of the substances they produce, our gut bacteria can affect our feeding behaviour [24]. What has only recently been discovered, however, is just how much they also affect obesity.

90% of our gut microbiome consists of two kinds of bacteria - Bacteroidetes and Firmicutes [25]. Many studies have noted that the ratio of the Firmicutes bacteria is higher in obese subjects, suggesting that they could be associated with a higher incidence of obesity [26, 27]. To add to that, previous studies have also shown correlations between weight loss and an increased amount of Bacteroidetes in stools [28, 29] making the association between these gut bacteria and weight even stronger [30].

A study even showed that when an obese person’s gut bacteria was transferred into the gut of a lean mouse, the mouse ended up gaining weight - suggesting that our gut bacteria could affect our ability to gain weight in the first place (further human studies would be needed before these results can be confirmed) [31].

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 our liver, fat tissue, muscles, and the brain can play a crucial role in harmonising these processes [32, 33].

Since this discovery, probiotics have garnered a lot of attention when it comes to beating obesity, and improving overall health (including gut health, of course) [34, 35].

You can read further on this subject and learn about a list of foods that can boost this inner ecosystem, for all the benefits of a healthy gut, right here. And if you have any questions about the article or would like to dig deeper into any aspect of it, drop a comment below! We’d love to hear from you. :)