depression and human gut microbiota

Depression And The Human Gut Microbiota

Depression and gut health are connected through the gut-brain axis. Learn symptoms of depression and gut health tips for mental health.

Major Depressive Disorder is one of the most common disorders responsible for disability in humans worldwide. Symptoms of depression include anxiety, sadness, loss of interest in actives, as well as thoughts of hopelessness and suicide. Depression symptoms can also be symptoms of another mental illness or mood disorder. That’s why it’s so important to get your depression under control. One of the most effective ways might be through the gut. 
The causation of this recurring condition has been found to involve dysregulation in neuroendocrine (hormonal), neurotransmitter, and metabolic systems. Let’s take a look at how this disruption affects the body, as we look at the depression and gut microbiota connection.


Warning About Mental Health 

Before we begin, it’s important to talk to a mental health professional if you are experiencing depression episodes, thoughts of death, or extreme changes in behavior. Interventions, such as psychotherapy and antidepressants are effective treatment options that can be life-saving.
Also, it’s important to talk to a mental health professional about a possible diagnosis. There are many types of depression, including Major Depressive Disorder, Persistent Depressive Disorder (Dysthymia), Clinical Depression, and Bipolar Disorder, to name a few. 
These medical conditions and their symptoms are fluid. There might be some overlapping depression symptoms that make a diagnosis and effective treatment challenging. However, it’s worth it!
Your mental health journey is one worth exploring because you are a valuable person. Discuss different approaches like cognitive-behavioral therapy (CBT), brain stimulation therapies, or repetitive transcranial magnetic stimulation
Not even sure what these things are? That’s why you should speak to a health care provider. Everyone is unique and so are the options to treat mental health conditions
There isn’t a one-size-fits-all approach to wellness. That’s why Thryve exists, too!  We celebrate the uniqueness and individuality of everyone. 


What Are Symptoms of Depression?


symptoms of depression

Depression hits everyone differently. These differences come down to many factors, including if it’s major depression, Seasonal Affective Disorder, or side effects to medications.
Common depression symptoms include:
Brain Fog
Mood Swings
Feelings of Worthlessness
Delusions or Hallucinations
Feelings of Guilt 
Low Self-Esteem
• Trouble Sleeping
Withdrawal from Activities and Loved Ones
Loss of Appetite or Binge-Eating
Alcohol or Substance Abuse
Suicidal Thoughts
If you experience one or more of these symptoms regularly, there is a chance you might experience a major depressive episode. Never hesitate to contact a mental health professional to discuss treatment options. 


How Can Gut Health Impact A Depressed Mood?

Over the years, there has been enough evidence pointing towards the role of gut microbes in neural development and function. Together, the intestinal bacteria represent a virtual organ of sorts inside of us. In fact, these cells have almost 100 times more genetic material present than all the cells in our human body.
Even though the role of gut microbes in neurological conditions has not been well established, there has been a rapid increase in evidence that underlines the possibility that changes in the gut microbial environment have an effect on the normal functioning of our nervous system. Hence, our gut environment can have a major role to play in our mood and also in depression.


Gut Microbiota and the Brain

There exists a bidirectional communication between our gut microbiota and the components of the gut-brain axis. This communication can influence the normal functioning of the gut and may contribute to a risk of diseases in humans.
Changes in gastrointestinal (GI), autonomic nervous system (ANS), immune system, enteric (intestinal) nervous system (ENS), and central nervous system (CNS) brought about by the microbiota can lead to alterations in the following:
• GI Barrier Function
Fat Storage and Energy Balance
Increased Stress Reactivity 
General Low-Grade Inflammation (GI and Systemic)
Depressive-like Behaviors and Increased Anxiety
All the above-mentioned mechanisms are found to be involved in the development of mood and anxiety disorders in humans.


Gut Microbiota and Mood

The vast number of bacteria that constitute the intestinal microbiome are engaged in interactions with each other, as well as its local environment, in a balanced manner. This tight-rope act is done to achieve the normal functioning of our body.
Microbes produce a wide range of biologically and neuroactive (acting on the nervous system) molecules, complete with neurotransmitters and an extensive set of short-chain fatty acids. Short-chain fatty acids are produced through fermentation, all of which have known and unknown effects on the nervous system.
Short-chain fatty acids are essential for repairing the gut lining. Maintaining a strong gut barrier can be beneficial in mental illness prevention.  
Our gut lining is held together by tight junctions that allow nutrients from the intestines to enter the bloodstream. Over time, this barrier gets weakened by environmental toxins, poor diet habits, and chronic stress.
Eventually, toxins from the intestines can permeate the bloodstream, destroying healthy cells and neurological processes. This process is known as gut dysbiosis (or leaky gut). Gut dysbiosis has been linked to several mental illnesses [1]
These direct and indirect effects of the intestinal microbes on the intestinal tissues, local immune system and their components, and the enteric (intestinal) nervous system, affect the neuronal pathways of our brain. The above-mentioned processes together influence our mood and cognition by acting upon the components of our neural system. Increasing evidence points to a strong relationship between our intestinal health and our mental well-being.


Serotonin and Gut Microbiome 

Many people who are diagnosed with depression receive a prescription for antidepressant medications. Some of the most common mental health prescriptions include selective serotonin reuptake inhibitors (SSRIs).
These medications prevent the body from metabolizing serotonin, our joy molecule, too quickly. Research shows that approximately 80% of our serotonin derives from our gut microbiome.

Serotonin In Gut and Depression

The amino acid tryptophan gets broken down into 5-Hydroxytryptophan (5-HTP), a precursor to serotonin. Intestinal absorption doesn’t require extra proteins or transport molecules to metabolize 5-HTP [2]. So, serotonin is more abundant here than in the brain.
Studies involving healthy female women found that four weeks of probiotic intervention that included Streptococcus and Lactobacillus strains improved serotonin levels [3]. 


Stress and the Microbiome

Depression is associated with altered gut microbial composition, richness, and diversity. In a study conducted where the researchers transplanted the microbiota signature found in depressed patients to rats whose own microbiota was purposefully depleted [3] This procedure induced the development of some of the behavioral (anxiety, anhedonia) and physiological features of the depressive state.
Studies have also shown the impact of early life stress in remodeling the gut microbial composition. Subtle changes in microbial acquisition and maintenance during the vulnerable early life period may contribute to the predisposition of the individual to stress-related disorders in adulthood. This can be a result of the effect of these subtle changes in our microbiome on the neuro signaling pathways of the brain-gut microbiota axis.
Additionally, those who are depressed are more likely to be predisposed to alcohol addiction. These statistics are especially true if a person has a family history of depression and substance abuse. 
There is growing evidence suggesting the role of our intestinal microbes in neural development, both centrally in the brain and in the enteric nervous system. Depression is characterized by alterations in the gut microbiota and hence, we need to understand our gut so as to ensure the healthy functioning of our bodily systems.
Understanding the gut-brain connection gives us more tools in treating depression and other disorders of the brain. By sequencing your microbiome with consumer testing like Thryve, you’ll be able to gain more insights into how each of these microbes may contribute to your mood. Probiotics have also shown in studies to reverse negative emotions and enforce positive thinking. All in all, this should be enough to give us a whole new meaning to the quote: “You are what you eat.”
Create a diverse gut microbiome that is conducive to a happier mood. Thryve Mood Enhancer contains strain-specific bacteria scientifically proven to boost energy, improve serotonin levels, and promote focus. Get a little support from your friends in your gut. You’re never alone! 


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[1] Clapp, M. Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: The gut-brain axis. Clinics and practice, 7(4), 987.
[2] Waclawiková Barbara, et al. “Gut Bacteria-Derived 5-Hydroxyindole is a Patent Stimulant of Intestinal Motility via Its Action on L-Type Calcium Channels.” PLOS Biology, Public Library of Science, 22 Jan. 2021,
[3] Cheng, Li-Hao, et al. “Psychobiotics in Mental health, Neurodegenerative and Neurodevelopmental Disorders.” Journal of Food and Drug Analysis, No Longer Published by Elsevier, 10 Feb. 2019, www.`949819300158.
[4] Liu, S., Guo R., Liu F., Yuan Q., Yu., & Ren, F. (2020). Gut Microbiota Regulates Depression-Like Behavior in Rats Through the Neuroendocrine-Immune-Mitochondrial Pathway. Neuropsychiatric disease and treatment, 16, 859-869. htts://

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