The Gut-Brain Axis: How Depression, Anxiety, and Obesity Are Linked

The Gut-Brian Axis article cover

If you’ve lost your zest for life, feel like an anxious wreck, or take a joyride through the entire range of human emotion on a daily basis (hello, exhaustion!), you might be able to blame it on a “confused” line of communication between your gut and brain.

Over the years, science has proven that gut bacteria have neurotransmitter receptors that allow them to communicate directly with your brain via neural pathways, such as the vagus nerve. In a way, they’re like a super complex, high-functioning phone lines (1).

This line of communication between the gut and nervous system is called the gut-brain axis. And research has proven that disturbances to this system are linked to a wide range of health ailments, including depression, anxiety, inflammatory gastrointestinal disorders, obesity, addiction, and even eating disorders (2).

How Gut Bacteria Affects Your Mood

Not to get too “TMI” on you, but have you ever been nervous or excited and suddenly had to poop? Or felt snappy and cranky when you’re bloated and haven’t had a quality BM in days? Perhaps you’ve gone from being ravenously hungry to completely nauseous when something upsetting happens. This, my friend, is the gut-brain axis in action.

As author Emeran Mayer explains in his book The Mind-Gut Connection, not only do gut microbes have neurotransmitters that allow them to communicate with your central nervous system (CNS), but they’re perfectly positioned in your GI tract (which is barely separated from your immune system cells) to gather and receive information from your brain. This means that your gut microbes know the very moment you feel stressed (and exactly how stressed you are), happy, anxious, frustrated, excited, nervous, or angry. In other words, what starts out as a thought in the brain creates a feeling or emotion that travels straight to your gut.

gut brain axis beyond addiction

Image credit: Beyond Addition

So, you know that “gut feeling” you have when something is off? This isn’t a figure of speech, but actually your gut bacteria’s involvement in helping with higher cognitive abilities, including intuitive decision making (3). How wild is that?

Like a double-edged sword, just as your mood influences and cause changes to your gut bacteria, your gut bacteria also influence your mood. And how gut bacteria impact your mood will depends on the health of your gut microbiome (a fancy word for internal environment), as well as how well your digestive system is functioning as a whole.

The Good Relationship Between Gut-Brain Axis and Gut Microbiome


A healthy gut microbiome is full of beneficial bacteria that break down, absorb, and assimilate nutrients from the foods you eat, which fuel every process in your body. Gut microbes also have another important job to do, which is to produce serotonin and dopamine, the “feel good” chemicals that help regulate and boost your mood. Approximately 90% of serotonin and 50% of dopamine are produced by the bacteria in your gut — another fact that really drives the gut-brain connection home (4).

When your gut is healthy, the lines of communication between your gut and brain will also function properly. Adequate serotonin is produced, the correct hunger and satiety signals are sent to and from your brain, proper nutrients are synthesized, and so on. As a result, you’ll feel energized, calm, and experience an overall greater sense of well being. This could also help you respond to mental stress better. (It’s a win-win!) That consistent, “happy for no reason” feeling? That’s a sign of good gut health.

However, certain factors present in your diet and lifestyle can harm your gut bacteria, suppress serotonin production, and completely “change” the communication between your gut and brain, which is when depression, anxiety, and other waves of difficult emotion arise (1).

Mood Disorders and Other Symptoms of an Unhealthy Gut Microbiome

Gut Brain Axis

When your digestion isn’t functioning optimally, a few things happen. First, your nutrient absorption is hindered, which affects the function of every system in your body. Second, poor digestion allows undigested food particles to accumulate in your GI tract, which attracts unhealthy gut bacteria to ferment them (5). This encourages the growth of bad bacteria in your system to outnumber the healthy gut microbes, which also happen to be your key communicators. Think of them as a highly intelligent customer service support team for your gut and brain — you don’t want to mess with them.

Microbial imbalances can also lead to inflammatory gut conditions such as gut dysbiosis, leaky gut syndrome, irritable bowel syndrome (IBS), SIBO, or candida. All of these conditions prevent your gut microbes from functioning and communicating properly. This “data” is then gathered and sent to your brain to notify your body that something is seriously wrong in your digestive tract.

The neural pathway this information takes to reach your brain causes your brain to respond with depressive-like behaviors, anxiety, panic, mood swings, and irritability. In fact, studies have even deemed irritable bowel syndrome a gut-brain axis disorder, where depression, anxiety, and obesity are frequently seen along with digestive symptoms in IBS patients (6).

The good news is that there are several things you can do support your gut health right now. Here are our top five.

5 Easy Ways to Improve Your Gut and Mood

Steamed Vegetables

#1. Eat Steamed Vegetables at Every Meal

A side of steamed broccoli might not be considered traditional breakfast fare, but having steamed vegetables at every meal is one of the quickest ways to improve your gut function. This is because steamed vegetables are rich in fiber, which act as prebiotics to help feed and recolonize your healthy gut bacteria (7). (Think of it like a healthy gut fertilizer!)

In the early stages of healing your gut, we recommend steaming vegetables rather than eating them raw (this includes steaming greens for smoothies, too). Steaming helps cook down and “predigest” the fiber, making it easier for your digestive system to break down.

Note: While grains and legumes are other beneficial plant sources of fiber, we recommend choosing vegetables as your primary fiber source, as the phytic acid in grains and legumes can be difficult to break down, which can cause  inflammation, irritate the gut lining, and aggravate digestive symptoms and conditions (8).

#2. Eat Fermented Foods

Fermented foods such as sauerkraut, beet kvass, kimchi, coconut milk yogurt, as well as probiotic supplements can help replenish the good bacteria in your system. And while fermented foods are a great place to start to improve gut health, they’re most beneficial for your gut when combined with a gut-healing diet.

#3. Follow a Gut-Supportive Diet

You’ll want to begin removing foods from your diet that cause inflammation in the GI tract and damage healthy gut bacteria, such as alcohol, processed sugar, gluten, and refined carbohydrates. To make things simple for you, we’ve created a free downloadable infographic on exactly which foods to eat and avoid to support a healthy gut.

#4. Drink Bone Broth

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There’s nothing like relaxing over a warm mug of bone broth, but it also happens to be one of the most powerful gut-healing foods on the planet. This is because bone broth is rich in the beneficial proteins collagen and gelatin, which are packed with anti-inflammatory amino acids, and help heal and seal the gut lining, which is exactly how you go about healing leaky gut syndrome and strengthening your intestinal lining to support the gut microbiome as a whole.

#5. Reduce Your Stress Levels

We know this one is easier said than done, but the simple act of scheduling in a non-negotiable self-care day each week to go for a massage, attend a yoga class, or simply sleep in (if that’s what your body needs) will help improve your mood. It can also go a long way in the gut-healing process, since your gut microbes are extremely sensitive to emotion.

By understanding the relationship between your gut and brain, you now hold one of the keys to improving your mood, relieving symptoms of depression and anxiety, and creating more joy in your life from the inside out.

If you’ve lost your zest for life, or feel anxious and depressed, you may be able to blame it on a complex line of communication called the gut-brain axis.

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