The Root Cause of Anxiety and Depression That Few Suspect

When you think about strategies to achieve optimal brain performance, you may think about doing crossword puzzles or learning a new language… adding more sleep or even eating more omega-3 fats may also come to mind.
Most people would not automatically think about their gut when they think about brain health… but this is actually a perfect place to look, one that may very well hold the secret to improving your mood, mental health and preventing other brain-related diseases, like Parkinson’s.

Does Your Gut Hold the Key to Better Brain Health?

You may not be aware that you actually have two nervous systems:

  • Central nervous system, composed of your brain and spinal cord
  • Enteric nervous system, which is the intrinsic nervous system of your gastrointestinal tract

Both are actually created out of the same type of tissue.

During fetal development, one part turns into your central nervous system while the other develops into your enteric nervous system.

These two systems are connected via the vagus nerve, the tenth cranial nerve that runs from your brain stem down to your abdomen.

It is now well established that the vagus nerve is the primary route your gut bacteria use to transmit information to your brain. That’s right… while many think of their brain as the organ in charge, your gut actually sends far more information to your brain than your brain sends to your gut.

To put this into more concrete terms, you’ve probably experienced the visceral sensation of butterflies in your stomach when you’re nervous, or had an upset stomach when you were very angry or stressed. The flip side is also true, in that problems in your gut can directly impact your mental health, leading to issues like anxiety, depression, and autism.

For instance, in December 2011 the Journal of Neurogastroenterology and Motility reported the novel finding that the probiotic (good bacteria) known as Bifidobacterium longum NCC3001 has been shown to help normalize anxiety-like behavior in mice with infectious colitis.i

Reportedly, the bacteria’s effect on anxiety involves modulating the vagal pathways within your gut-brain connection:

“As B. longum decreases excitability of enteric neurons, it may signal to the central nervous system by activating vagal pathways at the level of the enteric nervous system.”

Separate research also found the probiotic Lactobacillus rhamnosus had a marked effect on GABA [an inhibitory neurotransmitter that is significantly involved in regulating many physiological and psychological processes] levels in certain brain regions and lowered the stress-induced hormone corticosterone, resulting in reduced anxiety- and depression-related behavior.ii

When researchers severed the vagus nerve, GABA receptor levels and the animals’ behavior remained unchanged after treatment with L. rhamnosus, confirming that the vagus nerve is most likely the primary pathway of communication between the bacteria in your gut and your brain.

Interestingly, just as you have neurons in your brain, you also have neurons in your gut — including neurons that produce neurotransmitters like serotonin, which is also found in your brain. In fact, the greatest concentration of serotonin, which is involved in mood control, depression and aggression, is found in your intestines, not your brain! (Perhaps this is one reason why antidepressants, which raise serotonin levels in your brain, are often ineffective in treating depression, whereas proper dietary changes often help.)

Abnormal Gut Flora Fosters Abnormal Brain Development

There is a close connection between abnormal gut flora and abnormal brain development—a condition Dr. Campbell-McBride calls Gut and Psychology Syndrome (GAPS). GAPS is the result of poorly developed or imbalanced gut flora and may manifest as a conglomerate of symptoms that can fit the diagnosis of autism, attention deficit hyperactivity disorder (ADHD), attention deficit disorder (ADD) without hyperactivity, dyslexia, dyspraxia, or obsessive-compulsive disorder, just to name a few possibilities.

Dr. Campbell believes autistic children are born with perfectly normal brains and sensory organs, but once their digestive system becomes a major source of toxicity instead of being a source of nourishment, they start to develop autistic symptoms. This theory fits in well with new research published by the American Society for Microbiology, which identified a bacteria (Sutterella) that is unique to the intestines of children with autism.iii

The researchers reported:

“Many children with autism have gastrointestinal (GI) disturbances that can complicate clinical management and contribute to behavioral problems. Understanding the molecular and microbial underpinnings of these GI issues is of paramount importance for elucidating pathogenesis, rendering diagnosis, and administering informed treatment.
Here we describe an association between high levels of intestinal, mucoepithelial-associated Sutterella species and GI disturbances in children with autism. These findings elevate this little-recognized bacterium to the forefront by demonstrating that Sutterella is a major component of the microbiota in over half of children with autism and gastrointestinal dysfunction (AUT-GI) and is absent in children with only gastrointestinal dysfunction (Control-GI) evaluated in this study.”

Other links between your gut and your brain health have also been established, including:

  • A study published in Neurogastroenterology & Motility found mice that lack gut bacteria were found to behave differently from normal mice, engaging in what would be referred to as “high-risk behavior.” This altered behavior was accompanied by neurochemical changes in the mouse brain.iv
  • Research in PNAS found that gut bacteria may influence mammalian early brain development and behavior, and that the absence or presence of gut microorganisms during infancy permanently alters gene expression.v(In a similar way, probiotics have also been found to influence the activity of hundreds of your genes, helping them to express in a positive, disease-fighting manner.)

Through gene profiling, they were able to discern that absence of gut bacteria altered genes and signaling pathways involved in learning, memory, and motor control. This suggests that gut bacteria are closely tied to early brain development and subsequent behavior.

What Factors Lead to Compromised Gut Bacteria?

Your gut bacteria are an active and integrated part of your body, and as such are heavily dependent on your diet and vulnerable to your lifestyle. If you consume a lot of processed foods and sweetened drinks, for instance, your gut bacteria are likely going to be severely compromised because processed foods in general will destroy healthy microflora and sugars of all kinds feed bad bacteria and yeast.

Your gut bacteria are also very sensitive to:

  • Antibiotics
  • Chlorinated and fluoridated water
  • Antibacterial soap
  • Agricultural chemicals
  • Pollution

Because of these latter items, to which virtually all of us are exposed at least occasionally, it’s generally a good idea to “reseed” the good bacteria in your gut by taking a high-quality probiotic supplement or eating fermented foods. This is important for everyone, but imperative if you are a woman who is pregnant, as your newborn depends on you for its initial gut flora. Many women of reproductive age are deficient in a wide range of vitally important probiotic strains—a deficiency that transfers to their offspring, and may set the stage for any number of problems.

Dr. Campbell explains:

“The baby acquires its gut flora at the time of birth, when the baby goes through the birth canal of the mother. So whatever lives in mom’s birth canal, in mom’s vagina, becomes the baby’s gut flora. So what lives in mom’s vagina? It’s a very richly populated area of a woman’s body. The vaginal flora comes from the bowel. So if the mother has abnormal gut flora, she will have abnormal flora in her birth canal.”

Adding injury to insult is the significant decrease in breastfeeding. We now know that breastfed babies develop entirely different gut flora compared to bottle-fed babies. Infant formula never was, and never will be a healthy replacement to breast milk, for a number of reasons — altered gut flora being one of them.

Optimizing Your Gut Flora, and Thereby Your Brain Function, is Easy

When you consider that your gut is your “second brain,” it becomes easy to see how your gut health can impact your brain function, psyche, and behavior, as they are interconnected and interdependent in a number of different ways. Fortunately, optimizing your gut health is remarkably easy.

Here are my recommendations for optimizing your gut bacteria:

  • Eat fermented foods, as these are the best route to optimal digestive health as long as you eat the traditionally made, unpasteurized versions. Healthy choices include various pickled fermentations of cabbage, eggplant, cucumbers and onions. We will be posting loads of information on how to do this shortly. If you regularly eat fermented foods such as these that, again, have not been pasteurized (pasteurization kills the naturally occurring probiotics), your healthy gut bacteria will thrive.
  • Probiotic supplement. Although I’m not a major proponent of taking many supplements (as I believe the majority of your nutrients need to come from food), probiotics are definitely an exception. I have used many different brands over the past 15 years and there are many good ones out there. I also spent a long time researching and developing my own, called Complete Probiotics, in which I incorporated everything I have learned about this important tool over the years. If you do not eat fermented foods, taking a high-quality probiotic supplement is definitely recommended.
  • If you’re a new mom, breastfeed your baby. It’s not just a matter of vitamins, minerals, proteins and fats that makes breast milk far superior to formula. Research shows that breast milk also contains substances that may significantly enhance your baby’s gut and brain developmentvi — a gift that will literally last a lifetime.

By Dr. Mercola


Neurogastroenterology and Motility December 2011; 23(12): 1132-1139
ii Proceedings of the National Academy of Sciences 2011 Sep 20;108(38):16050-5.
iii MBio January 10, 2012, vol. 3 no. 1 e00261-11
iv Neurogastroenterology & Motility March 2011, Volume 23, Issue 3, pages 255–e119
PNAS February 15, 2011 vol. 108 no. 7 3047-3052
vi Molecular Nutrition and Food Research August 2, 2011