The Effect of Gut Bacteria on Mood

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You may have heard lots of talk recently about the importance of having a “healthy gut.” This is an emerging area of research and scientists are continuing to discover precise reasons why the gut (aka gastrointestinal system or GI tract) is one of the most important biological systems in the human body.

[Note: Terminology can vary when talking about gut health. For instance, intestinal flora (or gut bacteria) is often referred to as “microbiota,” and the biological system comprising these trillions of organisms is called your “microbiome.” In other words, you have trillions of microbiota in your microbiome, which reside in your GI tract, or gut. Another common term used to describe the beneficial / good gut bacteria is “Probiotics.”]

Here are just a few of the important discoveries researchers have made about the gut:

  • The majority of nutrient and water absorption takes place in the gut.
  • Around 20 hormone processes are connected to or have processes in the gut.
  • The GI tract contains more than 1 billion nerve endings and has more surface area than that of your external skin. These neurotransmitters, known as the enteric nervous system (ENS) are so involved in your body’s processes, scientists have nicknamed the gut the “second brain.”water and nutrient absorption takes place in the gut
  • There are over 100 million neurons in the ENS; more than the spinal cord, or the peripheral (outside of the brain or spinal cord) nervous system.
  • The brain doesn’t need to operate the GI system. The second brain can act independently. In some cases the ENS sends signals to the brain, not the other way round [1].
  • The “gut-brain axis” describes the influence the gut, microbiome, and ENS have on the brain, including both emotional and cognitive functions [2].
  • The gut contains 70% to 80% of your body’s immune cells.
  • The GI microbiome prevents colonisation by potentially pathogenic (“bad”) microorganisms, provides energy for the gut wall from undigested food, and it regulates the mucosal immune system [3].
  • GI microbiota contribute to energy homeostasis (stability), prevent mucosal infections and, importantly, contributes to the maintenance of an intact GI barrier, which seems to be closely related to infectious, inflammatory, and allergic diseases [4].
  • Any disruption to the harmony of the GI microbiome affects the function of the host’s (your body’s) defense systems.

Can Your Gut Health Impact Your Mood?

Probably the most surprising effect the Gut-Brain Axis and microbiome have on your body is that to do with mood [5].

Science has long-recognized much of our supply of neurochemicals originate in the intestines. Most of your serotonin is made there [6], as well as approximately 50% of dopamine.

However, it’s only recently that serious consideration has been given to the role our microbiota (the bacteria in the gut) play in creating those chemicals [7,8].

A 2015 story in The New York Times shares interviews and quotes with several scientists on the cutting edge of this area of research, including one of the first to propose the neurochemical aspects of the gut-brain axis − Mark Lyte, a microbiologist at the Texas Tech University Health Sciences Center [9].

Lyte and other researchers have found that among the many chemicals secreted by our microbiota, some are identical to the substances “used by our neurons to communicate and regulate mood, like dopamine, serotonin, and gamma-aminobutyric acid (GABA).

These, in turn, appear to play a function in intestinal disorders, which coincide with high levels of major depression and anxiety [10].”
research into the connection between gut bacteria and mood

For example, in 2014 a group of Norwegians studied the feces of 55 people, noting depressive patients had certain bacteria in common.

It’s due to this type of research that it’s becoming more commonly accepted that anxiety, depression, and several pediatric disorders, including autism and hyperactivity, are linked to gastrointestinal abnormalities [11].

It was once thought that stress caused the immune system to be weakened, which in turn affected how bacteria in our microbiome behaved. Now, somewhat revolutionarily, research indicates that certain bacteria actually cause stress, which then impairs the immune system.

The truly exciting aspect of all this science is work that Lyte and his peers are doing in the realm of reversing disorders. For instance, using the secretions of certain bacteria to relieve anxiety and elevate mood by putting the microbiome back into harmony—proposing probiotics (beneficial, life-giving organisms) can be tailored to treat psychological disorders. These are somewhat flippantly being referred to as “psychobiotics [12].”

One exciting study carried out in Sweden found that mice raised without microbes were far more active outside. Not only that, the microbe-free mice were observed to have less anxiety and be more daring overall.

Serotonin is a known factor in mood, anxiety and depression, to name a few of its functions [13,14]. The connection to the manufacturing and body’s use of this essential chemical (some consider it a hormone) is gaining increasing attention. Or, as a 2015 publication in Behavioral Brain Research stated [15]:

“The brain-gut axis is a bidirectional communication system between the central nervous system and the gastrointestinal tract. Serotonin functions as a key neurotransmitter at both terminals of this network. Accumulating evidence points to a critical role for the gut microbiome in regulating normal functioning of this axis … There is also substantial overlap between behaviors influenced by the gut microbiota and those which rely on intact serotonergic neurotransmission.”

More research is being done to identify the precise processes occurring, but it’s certainly becoming crystal clear… the health of your microbiome is essential for even your mental and emotional wellbeing [16].

One way to help support your gut health is with a quality probiotic supplement such as Organixx ProBiotixx+.

Organixx ProBiotixx+ formula contains a single, super-strain of Lactobacillus plantarum, designed to help alleviate constipation… eliminate gas and belly bloat… support your entire immune system… and give you total digestive protection.

Organixx ProBiotixx probiotic formula

Article Summary

  • The GI tract contains more than 1 billion nerve endings and has been nicknamed the “second brain.”

  • The “gut-brain axis” describes the influence the gut, microbiome, and enteric nervous system have on the brain, including both emotional and cognitive functions.

  • Anxiety, depression, and several pediatric disorders, including autism and hyperactivity, are linked to gastrointestinal abnormalities.

  • Secretions of certain bacteria can relieve anxiety and elevate mood by putting the microbiome back into harmony.

Reader Interactions


  1. so what do I have to do, to be I agood mood and how do I drain the swamp in my gut – so that it functions like I was 10

  2. My mother slowly changed as a person over many years, she was not herself you could say. The family noted aggressiveness and anxiety, ramming talk and moodiness then came the muscle control issues and tics. Dementia was considered. She deteriorated rapidly ending in hospitalisation in a near uncontrollable paranoid state.
    Celiac – after a year to diagnose then two years to stabilise my mother was living independently again and managing entirely on her own. And MOST important of all, she was the person I knew as my mother who lived independently another 11 years until age 84.
    There are NO medications for Celiac, it is ALL nutrition and as a Psychologist it questioned much of what I had learnt about personality, character, attitudes and behaviour. Fix nutrition first.

  3. I have suffered from anxiety and depression on and off all my life but function with that and a busy family life. I decided to start doing coffee enemas for a time due to family health issues. On one occasion after feeling quite down and sluggish I decided to do an enema. Immediately following I had the most amazing energy surge that lasted the day. My life seemed to sparkle for that time! I have wondered why, on that particular day I felt so amazing afterwards and I can perhaps conclude it may have been due to the removal of some nasty bacteria from my gut?!! Fascinating stuff!

  4. I have acid reflux and take Omoprazole every day for over 5 years now. There’s a whole list of side effects with osteoporosis and malnutrition being the main ones. I need to stop taking them but when I don’t my stomach feels inflamed after anything I eat. Is there some natural remedy for this?

    • Hi Cindy have you tried taking milk kefir? It is rich in probiotics and has a calming effect on you digestive system.

    • My wife was taking this stuff every day too, except in New Zealand it’s called Losec. I found a product called Digest RC (black radish and other components) that she now takes before the evening meal. She has now almost completely weaned herself off Losec and she’s very happy about that. PPIs such as Losec and Omeprazole have never been tested for long term effects because they were originally intended for short term use only.

    • I had taken omeprazole for YEARS, along with other meds. Started having nearly every bad side-effect on the lists and went “cold turkey” from them all–started trying to just wean off, take less, but it wasn’t happening quick enough. Heard turmeric could help wean from the omeprazole and tried it–very cautiously. My GERD isn’t perfect, but mostly isn’t even there unless I stuff myself!

    • Taking a spoon of raw, organic apple cider vinegar in water every day got rid of my acid reflux, and its a natural probiotic too. In addition, the digestive enzymes from Epigenetic Labs, (now Organixx), after a heavy meal are a God send. Please try to get off those meds. God Bless.

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