Does Our Gut Effect Our Mental Health?


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If you read my last post, I touched a little on how the health of our gut can have a dramatic effect on our mental health, specifically with mental states like anxiety and depression.  It can be argued that due to our modern lifestyle, the gut health of the general public has been utterly demolished due to unnatural foods, high stress environments, and repeated exposure to antibiotics and other compounds that alter our gut flora.  Could it be a coincidence that these factors have come into play along with a dramatic rise in mental illness.  I think not.  More and more research is coming out that indicates a healthy gut is not only preferred but is necessary to maintain steady mental health and is key to maintaining lifelong wellness.

The reason why the health of our gut is important, is because of something called the gut-brain axis.  You may have heard the gut referred to as the “second brain”.

The Gut Is Our “Second Brain”

In the gut lies the enteric nervous system, a vast network of neurons along the intestinal lining.  It is referred to as the second brain because of the sheer size, complexity, and role that it plays in working with our brain to provide both signaling and feedback to stimuli.  There is a direct link to the brain via the vagus nerve, with the enteric nervous system sending neurotransmitters like serotonin and GABA.  These are chemicals that signal vital processes within the brain.

While all of our higher thinking is done in the brain (think doing math, writing an email, problem solving), much of our emotion, subconscious response, and instinct may originate in the gut.

Evidence is emerging on just how important this connection is, and novel therapies are developing to heal the gut so we can heal our mind.

Depression and Anxiety

The rate of depression in the U.S is staggering.  You could consider it an epidemic, with over 16 million adults and 12.8% of adolescents having major depressive disorder.  That is a lot of people having trouble getting up in the morning and wondering how they are going to get through their day.  Many of these children and adults are on heavy medications to deal with their depression, often with undesirable side effects.  We can’t forget about the countless others that suffer from long bouts of sadness, or are just plain unhappy.  This doesn’t seem right.  What reason would there be for our biology to predispose us towards sadness?  An answer may lie in the gut.

People suffering from depression are being found to have specific profiles of bacteria in their gut.  Specifically, people with depression have been found to have higher levels of Enterobacteriaceae and Alistipes, but reduced levels of Faecalibacterium.

Supplementing with probiotics (live strains of beneficial bacteria) has been showing promising results.  In this recent study, patients were giving a probiotic containing three different strains of bacteria (Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum).   After 8 weeks patients had significantly decreased scores on the Beck depression test, as well as decreased serum insulin levels, indicating improved insulin sensitivity.

Another population that often struggles with severe depression is new mothers.  Postpartum depression effects 1 in 7 women, and is often drug resistant clinical depression. In a randomized control study of 423 women in the postpartum stage, those that were given a probiotic containing the same bacteria in the earlier study showed significantly lower scores of depression and anxiety symptoms.

Emotional Processing and Reactivity

Maybe it’s not straight up depression that is ailing you, but a near constant state of general sadness.  Maybe anger or distress are emotions that come up very easily without much provocation.  As far as my own mental health goes, bouts of depression have come and gone, but my emotional reactivity is something I have been working on for a long time.  I’ve talked before on the importance of mindfulness.  Bringing our wandering mind into the present is a technique that has been shown to dramatically reduce stress and anxiety.  Simply being aware of these emotions coming and going is enough to decrease their hold on us.  I have gotten very good results from practicing mindfulness techniques and meditation.

But what if it goes deeper than that for some? No matter what SSRI meds they take, or meditation hours they log, emotion remains an uncontrollable force in their live.  There is evidence that our gut has much to do with our emotional processing and control.

A study was done looking at healthy women and alterations in reactivity after 4 weeks of fermented dairy intake (dense source of probiotics).  After the 4 week mark the women showed dramatically reduced emotional reactivity, and heightened ability to objectively make judgements.  Functional MRI testing was done before and after, showing changes in the parts of the brain involved in emotional processing.

It looks like prebiotics have a similar effect on reactivity and general mood.  Think of prebiotics as food for your stomach bacteria.  These are indigestible fibers that feed certain strains of healthy bacteria like Lactobacillus and Bifidobacterium,  bacteria that have been shown to be some of the most benefit to the health of our gut.

In a study looking at 45 healthy volunteers, a group was given a prebiotic supplement containing either fructooligosaccharides or galactooligosaccharides, while the other group was given a placebo.  Serum cortisol levels were taken on the day before supplementation and on the final 21st day.  The results showed a decrease in stress hormone cortisol levels in the group that received prebiotics, as well as a decrease in attention paid to negative stimuli and an increase in attention paid to positive stimuli (through an emotional batter test).

Although all of this research looks promising, the mechanisms are still not understood. We don’t know exactly why certain bacteria affect our brain positively or negatively, we can only look at associations with most of it.

Gut health is one factor in maintaining optimal health and wellness.  Don’t focus so much on buying expensive probiotics if it comes at the expense of eating real food.

  • Get out in nature and get dirty more
  • Strive to find organic, local produce to avoid gut altering pesticides
  • Eat some fermented foods like kefir, kombucha, kimchi, and yogurt
  • Eat some prebiotic fiber 

Thanks for reading everyone.  Don’t hesitate to leave any comments or questions below!
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