The Effect of Gut Bacteria on Mood

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,as well as approximately 50% of dopamine.

However, it’s only recently 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 moodFor 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.

Thus, 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, “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.”15

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 of the best ways to support your gut is with a quality probiotic supplement. ProBiotixx from Organixx contains three amazing components that will improve your digestion, support your immune system, and help restore healthy bacteria in your gut.



  1. Gut health’: a new objective in medicine?
  2. Ibid
  3. Lymphoid tissue genesis induced by commensals through NOD1 regulates intestinal homeostasis.
  4. Allergy and the gastrointestinal system
  5. Serotonin, tryptophan metabolism and the brain-gut-microbiome axis.
  6. Serotonin: Facts, What Does Serotonin Do?
  7. Gut bacteria help regulate serotonin levels
  8. Serotonin, tryptophan metabolism and the brain-gut-microbiome axis.
  9. Can the Bacteria in Your Gut Explain Your Mood?
  10. Ibid
  11. Correlation between the human fecal microbiota and depression.
  12. Can the Bacteria in Your Gut Explain Your Mood?
  13. Serotonin: Facts, What Does Serotonin Do?
  14. Pharmacology of serotonin: what a clinician should know
  15. Serotonin, tryptophan metabolism and the brain-gut-microbiome axis.
  16. The microbiome-gut-brain axis during early life regulates the hippocampal serotonergic system in a sex-dependent manner.

Reader Interactions


  1. Pretty amazing research!
    What does this mean for people on long term medication with mental illness diagnosis?

    • It implies that probiotics could have a place in the longterm treatment modalities. However, since it is an “emerging” area of research, we likely won’t know the full impact for decades to come. Very exciting stuff!

      • It’s only “emerging” here in the USA. Other countries have been consuming probiotic foods for thousands of years and already know about their health benefits. Glad we’ve finally recognized it. 🙂

  2. Hi
    Just wanted to ask if the multivitamin with Fulvic acid i am taking is enough for my daily intake?

  3. LS, as I suffer from chronic diarea for years and even after many medical examinations (colonoscopy and scans)my internist told me: may be you belong to aspeial type of peole we cannot help..So may be you can do for me something..

  4. I heard that you should not do oils internally ….very confused is this true as I was diagnosed with breast cancer and I use Frankincense but they told me there is no research on this could you please help clear this up for me, as I follow all your videos and have many of your ebooks and try and keep up with both of you and love it ….what do you recommend …I know you can not make any claims, I am aware of what is happening but what oils are good and bad I not sure, need some help in this area ….Thanks Sue

    • Hi Sue, I looked at this the other day and apparently the English study belief is you can’t take oils internally and the French study belief is that you certainly can. Both are based on different methods. Look at ‘doTerra’ range. I saw a webinar recently and have been looking into it myself. I hope that is of some help.

  5. 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

  6. 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.

  7. 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!

  8. 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?

  9. we, as human beings are totally surrounded,, and outnumbered by the medical establishment and big pharma, and and big corporations. We are not only in the last line ,when it comes to information, but “they” are trying to advertise us out of doing whats best for our health, “they” really don’t want us to know what that is.
    Thank God!! for people like you all who are trying to inform the masses!
    Perfect example of what I said is the very fact that other countries are way ahead of us(in nutrition) in the US, where we are suppose to be free,. thanks for the soap Box, I’ve been on anti-biotics most of my life and now, for the last 30yrs, had to be on anti-depre ss & anxiety meds

  10. Cindy , have you been tested for the H-pylori bacteria? Your description
    sounds like that is your problem. A Dr. would need to diagnose you

  11. Hi, Cindy. By experience l can tell you, if you eat two purple raw potatoes a day, immediately you will stop taking imeprazole.

    • Hi Elza, your reply to Cindy is quiet interesting. We are used to consuming raw food such as green vegetables, radish, carrot, tomatoes and sprouted beans etc, but I have not heard potato to eat raw because we are told by our seniors never take potato not cooked. Will you tell me what is that chemical in potato to replace imeprazole?

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