Hidden Cause of Depression and Anxiety

author avatar Dr. Eric Berg 08/31/2023

Let’s talk about another hidden underlying cause of depression and anxiety. It has to do with your microbiome, the good bacteria in your gut, and the unexpected connection between your gut and your mood.

The short version? There’s a huge connection to your state of well-being and your digestion, and you need to take care of your gut if you truly want to feel healthy and thrive.

In this article, I will cover:

Let’s dive into the details.


Depression and Anxiety

Depression and anxiety mood disorders

Symptoms of Depression and Anxiety

Depression and anxiety are cognitive disorders categorized by various symptoms. Symptoms of depression can include:

  • Fatigue or loss of energy almost every day
  • Feelings of worthlessness or guilt almost every day
  • Impaired concentration, indecisiveness
  • Insomnia or hypersomnia (excessive sleeping) almost every day
  • Markedly diminished interest or pleasure in almost all activities nearly every day (called anhedonia, this symptom can be indicated by reports from significant others)
  • Restlessness or feeling slowed down
  • Recurring thoughts of death or suicide
  • Significant weight loss or gain (a change of more than 5% of body weight in a month).

Similarly, for anxiety disorders, symptoms can include:

  • Feeling nervous, restless or tense
  • Having a sense of impending danger, panic or doom
  • Having an increased heart rate
  • Breathing rapidly (hyperventilation)
  • Sweating and trembling
  • Feeling weak or tired
  • Trouble concentrating or thinking about anything other than the present worry
  • Having trouble sleeping
  • Experiencing gastrointestinal (GI) problems
  • Having difficulty controlling worry
  • Having the urge to avoid things that trigger anxiety

Treatment For Depression and Anxiety

Generally, in the United States, these mood disorders are seen as purely psychological conditions - and people suffering from them are treated accordingly. This treatment, then, usually involves mental treatment:

  • Meditation
  • Psychiatric treatment
  • Psychological treatment
  • Anxiety or depression medication
  • Exercise
  • Cognitive-behavioral therapy
  • Etc.

Unfortunately, this route of treatment completely ignores the brain-gut connection, which could ultimately be the source of these disorders for many people.


Understanding the Brain-Gut Connection

The brain-gut connection is super important for physical and mental health

Your brain and your colon are connected through something called the vagus nerve. It’s the longest nerve in the body.

Now, what’s interesting about the vagus nerve is that it’s a two-way street, but only 10% of the information is going from the brain to the colon. Conversely, about 90% of this communication flows from the colon to the brain, so the gut is the big informer here.

In other words, you’re getting a lot of feedback in your brain from things that are happening in your gut - especially with all the things that are connected to the good bacteria.

Good Bacteria Make Neurotransmitters

Now what you need to know - which is not really commonly known - is that your good bacteria make neurotransmitters. In fact, they make a lot of neurotransmitters which are identical to the ones that your own body makes.

So here you have these microbes that really are symbiotic. They’re working with your body helping you make really essential neurotransmitters like:

  • Acetylcholine
  • GABA
  • Norepinephrine
  • Serotonin
  • Dopamine

All of these neurotransmitters are going to make you feel calm, stress-free, and happy. So if there’s any problem with the microbes that are making these neurotransmitters, that issue is going to be transmitted up to the brain and you’re going to have physical and mental symptoms.

Your Gut Communicates With Your Parasympathetic System

The portion of the nervous system that receives the signals from your gut is part of what’s called the parasympathetic nervous system.

The parasympathetic system, on the other hand, is all about rest, digestion, and recovery. It directly opposes the sympathetic nervous system, which is in charge of fight or flight. When you are feeling major anxiety symptoms - or even an anxiety attack - the sympathetic nervous system is active.

Your Microbiome Bacteria Also Make Important SCFAs

Ok, so we understand that if there’s stress in the gut, it’s going to travel up to the brain and you’re going to feel it in this system. Worry, anxiety, panic, depression - all of these things can occur if your gut is not right.

Something else to keep in mind about microbiome bacteria is that they eat fiber from vegetables, and they make small chain fatty acids (SCFA) as a by-product of that fiber. So these microbes are converting this fiber - which is a carbohydrate - to a type of fat.

This is also super important for mental and physical health. That specific type of fat can provide up to 90% of the energy for the colon cells.

It also helps improve Fat Storing Hormone resistance, which has to do with your blood sugars. Finally, it also supports the integrity of your gut lining, which is super important for digestion and the absorption of nutrients.

In short, these SCFAs have a very important purpose. If you don’t have enough, you’re also going to be tired. That’s going to feel like depression, but really you’re just exhausted or tired because your cells can’t make the energy or complete the functions that they need.

So the combination of a lack of neurotransmitters and a lack of SCFA could make you feel quite crumby.


Microbiome Health - Not Medication - Can Keep You Healthy

The reason I’m bringing this up is that if you’re not aware of this connection and you decide to go down the “traditional” medical route and take drugs without understanding the root cause, you might not ever solve the real problem.

In fact, you may even make it worse, as many medications kill your “good” gut bacteria along with any pathogens they were designed to target.

Also, if there’s inflammation going on in the intestinal tract - or even if the microbes move to the small intestine, which is called small intestinal bacterial overgrowth (SIBO) - that can cause a lot of stress in the brain as well.

Why? Because those microbes in the wrong place are eating up all your nutrients and leaving you with a B-vitamin deficiency (and you’re going to feel stressed from that).

The point I wanted to make is that there’s a huge connection to your state of well-being and your digestion.


Mental Stress Can Also Affect Digestion

Mental health affects gut health

Now, on the flip side, if you are stressed in your brain, that can also affect your digestion.

You’ve heard about the concept of being stressed and getting an ulcer. That’s a real thing, and it happens because of this brain-gut connection.

The other thing to know is that this communication that goes down from the brain to the digestive tract also controls:

  • Enzyme release
  • Acid production
  • Hormone release
  • The muscles around the colon

So you can have stomach pain from spasm - the increased or the decreased speed at which the colon works - along with diarrhea or constipation.

You could have an overly acidic stomach and lack of enzymes, which can inhibit your ability to digest food.



The point? Your gut could be majorly affecting your mental health and your overall physical wellbeing. If you’re dealing with any of these symptoms, then, the first thing you want to investigate is your gut health.

For more information about how to support a healthy colon, check out this video.

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Disclaimer: Our educational content is not meant or intended for medical advice or treatment.

Editor’s Note: This post has been updated for quality and relevancy.

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