• Gavin Guard, Medical Director

A Missing Link to Mental Health

Updated: a day ago

Key Takeaways

· Mood disorders like anxiety and depression are very common (7% have depression, 18% have anxiety)

· Anti-depressant drugs are the 2nd most common prescribed drug but have their own set of problems (side effects, poor responsiveness)

· Gut health is a key aspect of mental health and mood

· Focusing on gut health is a major way to address brain health

Current model of anxiety and depression

Mental health conditions like anxiety and depression have seen an uptick in numbers over the last few decades. In fact, 7% of Americans have depression and 18% have anxiety. One study noted that up to 1 out of 3 people will be affected by anxiety symptoms.

As the 2nd most common drug class, it’s not uncommon for a clinician to prescribe an anti-depressant like Prozac, Zoloft, Celexa, etc. However, 30-40% of individuals don’t respond to these anti-depressants. And these drugs don’t come without a cost; fatigue, weight gain, sexual dysfunction/loss of libido, and gut upset are some of the most common side effects experienced on these drugs.

Learn how probiotics can help anxiety and depression

A new look at what causes anxiety and depression

Anxiety and depression should not be the status quo of your life. These are conditions that may have a physical cause (as well an emotional component). Through my research, I’ve come to acknowledge a missing link to mental health and mood. This aspect of health plays a key role not only in regulating inflammation, but also brain health in general.

As you may already know, there is a well-established, clear connection between the gut and the brain. This is called the “gut-brain axis” and the connection between the two is bi-directional. This means that the brain affects major gut functions like motility, producing stomach acid and digestive enzymes, producing antibodies, regulating the microbiome (the bacteria that live predominantly in the large intestine). In return, the gut feeds back information to the brain through the vagus nerve.

How does gut health affect mood disorders?

It’s no surprise then, that poor gut health may be a leading driver of things such as anxiety and depression. To put things into perspective, researchers have found different gut bacteria profiles (microbiomes) in those with depression. This may be attributed to the fact that 95% of serotonin (that feel good neurotransmitter) is produced in the gut. In addition, 400-500 times more melatonin is produced in the gut than in the brain. Gut bacteria also produce dopamine and other neurotransmitters important in brain health and function. You can start to imagine how gut health may not only be important in your mood, but also your sleep-wake cycle.

Many studies have been performed in rats where researchers have manipulated their microbiome (gut bacteria) and measured anxiety-like and depressive-like behaviors. In one study, exposure to a harmful bacteria (Campylobacter jejuni) lead to increased levels of anxiety-like behavior in mice 2 days after infection. This may be due to the infection’s ability to lower a key aspect of brain health, called brain-derived neurotrophic factor (BDNF). Infection may also negatively affect brain health by producing inflammatory molecules that then enter the brain.

In many of these infection studies, reversal of behavioral changes was possible through administration of different strains of probiotics. Some studies suggest one mechanism may be due to the fact that healthy bacteria produce more GABA, a major calming neurotransmitter found in the brain.

While we must realize that these studies are done in rats, it gives us important insights into how our own human gut health could be affecting these common mood conditions we may be experiencing. However, there have been some well-designed studies looking at humans. Let’s take a look at these.

Learn how probiotics can help anxiety and depression

In a human study, this time a double-blind, placebo-controlled, randomized clinical trial, participants were given a probiotic for 30 days. Using questionnaires to measure mood states, the researchers concluded that “the probiotic treatment group demonstrated significantly less psychological distress than did matched controls.” These findings were replicated in another well-designed human trial with a different type of probiotic. In addition, individuals with IBS (irritable bowel syndrome) and IBD (inflammatory bowel disease) had higher levels of anxiety and depression.

Finally, in a meta-analysis (a study looking at multiple other studies), 52% of the studies examined showed that manipulating gut health could improve anxiety-like symptoms.

It’s important to note that not one medication, supplement, or diet is going to fix your gut issues, and thus, your brain health and mood. I am confident that when taking an integrated approach to gut health, 52% may look more like a 70-90% success rate.

The Bottom Line

The long-story short is that gut health certainly impacts brain health and the regulation of mood. In multiple research models, including both rats and well-designed human trials, manipulating gut health has shown to be a promising way to increase your mood.

Work with me to heal your gut

There’s no one-pill fix here though. You need to take a careful look at identifying the limiting factors affecting your gut health and then take a multi-prong approach in fixing these issues.

The health of your gut should be a serious consideration for anyone suffering from some of these mood conditions. I believe no one should have to live with these symptoms indefinitely. Knowing that there may be a physical cause to your symptoms is both empowering and hopeful.

I hope you found this information useful and helpful in your journey back to a healthier and happier life.

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Resources Cited

· Koloski, N A et al. “Evidence that independent gut-to-brain and brain-to-gut pathways operate in the irritable bowel syndrome and functional dyspepsia: a 1-year population-based prospective study.” Alimentary pharmacology & therapeutics vol. 44,6 (2016): 592-600. doi:10.1111/apt.13738

· Wang, Hong-Xing, and Yu-Ping Wang. “Gut Microbiota-brain Axis.” Chinese medical journal vol. 129,19 (2016): 2373-80. doi:10.4103/0366-6999.190667

· Yang, Beibei et al. “Effects of regulating intestinal microbiota on anxiety symptoms: A systematic review.” General psychiatry vol. 32,2 e100056. 17 May. 2019, doi:10.1136/gpsych-2019-100056

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Gavin Guard, MPAS, PA-C, CISSN


818 Mullis St, Suite #6

Friday Harbor, WA 98250




Medical Disclaimer: Any information on this site is for educational and informational purposes only, and does not substitute for direct medical care, nor can the content be implied to be medical advice, diagnosis, or treatment.