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Have you ever had that “gut feeling” before? You know the one – You’re about to get up and give a speech, and suddenly, you have butterflies in your stomach. Or how about when you get depressed or anxious, and suddenly you crave junk food? You may recall ending a rough day by sitting on the couch and eating an entire pint of ice cream. You may have also watched a feel-good movie or poured yourself a glass of wine. 

Sound familiar? Stressful times seem to call for some form of comfort food or beverage. At the same time, stress may cause digestive distress or either increase or decrease appetite. Why would emotional stress cause digestive symptoms or food cravings? Perhaps feelings of stress, anxiety, or sadness aren’t just in your head after all…  

It may be time to explore neuroscience from the perspective of the gut-brain axis and “the second brain.” 

The Gut-Brain Axis and The Second Brain

Scientists have known about the gut-brain connection for a while now. Dan Hurley wrote an article for Psychology Today back in 2011 investigating this connection between the central nervous system (CNS) and the gastrointestinal system, often referred to as the gut-brain axis. The transmission of information between the two occurs via the vagus nerve, the tenth cranial nerve, and the primary component of the sympathetic “rest-and-digest” aspect of the nervous system. 

The gut-brain axis includes several systems and components, including: 

  • The neuroendocrine system 
  • Neuroimmune systems 
  • The hypothalamic-pituitary-adrenal (HPA) axis  
  • Sympathetic (“fight-or-flight”) and parasympathetic (“rest-and-digest”) nervous systems 
  • The enteric nervous system (ENS) 
  • Vagus nerve 
  • Gut microbiota 

The enteric nervous system (ENS) is the nervous system of the gut. It’s the gut’s “brain.” The ENS has 100 million neurons more than there are in the spinal cord but fewer than in the brain. It can work completely on its own to control the movement and absorption of food throughout the intestines – without ANY input from the brain. 

Columbia University professor Michael Gershon, MD, is regarded as the “father of neurogastroenterology,” the marriage of the fields of neurology and gastroenterology. Gershon confirms, “The gut can work independently of any control by the brain in your head – it is functioning as a second brain. It is another independent center of integrative neural activity.” Gershon authored a book, “The Second Brain,” to further explain his discoveries. 

Gut Health Affects Brain Function

So, if the gut works independently of the brain, how can it affect our mood? Well, the gut-brain axis is a two-way street. The ENS also sends signals to the brain that directly affect our mood centers – making us feel happy or sad, stressed, or depressed. The gut even sends signals to our brain that influence memory, learning, and decision-making.  

The gut microbiome plays an important role in ENS signaling. These microorganisms can influence the brain by producing the following: neurotransmitters, cytokines, chemokines, neuropeptides like peptide YY, and metabolites like branched-chain amino acids (BCAAs), short-chain fatty acids (SCFAs) like butyrate, and others.  

You may be familiar with a few of these, like serotonin, the “feel good” neurotransmitter, or dopamine, the “motivation” neurotransmitter. Bifidobacterium and Lactobacillus species in the gut produce the neurotransmitter GABA (gamma-aminobutyric acid), a neurotransmitter associated with anti-anxiety effects. Candida, Escherichia, and Enterococcus species manufacture serotonin, and some Bacillus species make dopamine. 

If you have ever made a big decision and immediately afterwards felt sick about it, your gut just sent a message to your brain through vagal pathways, and you might want to re-think that decision! Or it may be outside your comfort zone, and there’s an opportunity to make a major breakthrough. 

Food is Often The Missing Link

The ENS sends signals to the brain that directly affect your moods and thinking. What determines what kind of messages it sends? FOOD. Your dietary choices determine the messages sent to the brain and the moods, emotions, and thoughts you have. Your gut bacteria even have neurotransmitter receptors –just like in the brain. 

One well-known example is the amino acid tryptophan, which converts into the neurotransmitter serotonin. You can find dietary tryptophan in protein-rich foods like poultry, eggs, fish, and cheese. If you follow a vegan diet, you may have to be more intentional about getting adequate amounts of this critical nutrient. 

Additionally, the traumas, toxins, and thoughts leading to immune modulation and inflammation may send tryptophan down a different metabolic pathway than it should: down the kynurenine pathway. The result is the generation of pro-inflammatory quinolinic acid rather than calming serotonin and subsequent sleep-promoting melatonin.  

That’s just one example. The food choices we make can also lead to inflammation in the gut, which then translates into inflammation in the brain. The macronutrient content of our diet (the percentage of protein, fats, and carbs) also impacts the brain. 

How Do We Know This?

According to the Journal of Clinical Investigation, Belgian researchers have found that specific components in foods exert a direct effect on neurohormones in the gut that then signal the brain. Let’s take a closer look at the study they did: 

Belgian researchers enlisted healthy, normal-weight human volunteers who agreed to bypass all the pleasurable aspects of eating by having a gastric feeding tube deliver nutrients directly to their stomach—while they underwent brain scanning. Through that tube, volunteers received either an ordinary saline (salt water) solution or an infusion of fatty acids (Lauric acid).  

At the same time, they listened either to neutral or melancholy music proven to induce sad feelings, or they were shown pictures of either neutral or sad faces. Fat, even without pleasant associations (Grandma’s butter cookies), can lift emotions. Based on the reported feelings and brain imaging results, the fatty acids reduced both sad feelings and sensations of hunger by about half, compared to the saline.  

Within minutes of the fatty acids hitting the stomach, MRI scans showed activation of brain regions known to moderate emotions. There were higher levels of blood flow in the brain stem and the emotional region of the brain, the limbic system. The researchers reported that fatty-acid infusion lessened both the behavioral and neural responses to sad emotion induction.  

This demonstrates that what you put in your stomach directly affects your mood. And it also demonstrates that your body needs good fats to make you happier. The big question we need to ask is: “How do we know if the food we are eating is good for our GI, or not?” 

Well, as practitioners, we know each person has a unique biochemistry and needs to be tested properly to determine which foods will result in a positive GI response and which will result in a damaging one. If you are experiencing mood disorders, depression, and other mental health issues, it could be due to what you are EATING. It’s also possible that foods that are overall healthy may be harming you. 

We Don’t Guess, We Test!

One of the simplest tests to determine which foods are damaging your GI is a Food Allergy Test. This is a simple blood test, and a laboratory like ImmunoLabs, which we use, provides a thorough presentation of results.  

One thing many people notice when they look at this test is that the foods listed are not necessarily unhealthy. After all, the list includes foods like eggs, lettuce, kale, broccoli, and cranberries. What they do not understand is that the immune system is heavily controlled by gut bacteria. Eating foods you are allergic to (even if they are organic and healthy) can trigger immune cells in your gastrointestinal tract, creating inflammation and resulting in adaptive biochemical reactions.  

Ultimately, these adaptive biochemical reactions affect your brain. You won’t know which foods are causing inflammation for you unless you test. Now, some of you may be thinking, “Don’t most allergic reactions look like hives or some other anaphylactic response?” Not necessarily. 

Inflammation in the gut can result in symptoms such as headaches, bloating, indigestion, increased motility (diarrhea), decreased motility (constipation), abdominal pain, gastrointestinal disorders like irritable bowel syndrome (IBS), and even brain fog. Many people experience these things daily and don’t realize that they don’t need to feel that way… Some food allergies you can reverse. 

The Gut Influences The Development of Neurological Disorders

The field of psychiatry is just beginning to recognize the gut microbiome’s influence on cognitive function. Gastroenterology and psychiatry are finally coming together!  Eliminating pathogens and maintaining intestinal homeostasis is crucial if you want a healthy brain as you age. Scientists have found a connection between gut dysbiosis and the following conditions: 

  • Depression 
  • Anxiety 
  • Autism 
  • Attention Deficit Hyperactivity Disorder (ADHD) 
  • Alzheimer’s disease 
  • Parkinson’s disease 
  • Exaggerated stress response 
  • Metabolic disorders like obesity 

So far, most research on these conditions and their connections to gut microbiota has used animal models, particularly mouse models. However, clinical experience indicates that the human gut works similarly. 

How Did This Happen?

One of the most common contributors to all these allergies and GI problems is antibiotic use as a child. Another significant one is the childhood vaccination schedule. Both practices disrupt the microbial balance in the gut, leading to overgrowth and decreased presence of beneficial bacterial strains. That is why restoring your normal gut flora with supportive interventions like prebiotics and fermented foods and drinks is crucial.  

Another terrific way to support gut healing is to supplement with a product called Megabiotic Formula, an allergen-free probiotic that delivers 100+ billion CFUs of beneficial bacteria, which is over and above a standard probiotic. 

The Wellness Way Approach to Restoring The Gut-Brain Axis

There is no need to beat yourself up over your choices in the past, but once you know better, you can do better. If you currently suffer from mood- or neurological disorders, please take the time to do a Food Allergy Test. You never know – it could be a gut issue, not a brain issue. But you will never know until you get tested. Once you have gotten your test results, your Wellness Way practitioner will design a personalized nutrition program that best suits your needs. Reach out to a Wellness Way clinic today to get started!  

Resources: 

    1. Your Backup Brain | Psychology Today 
    2. The Microbiota-Gut-Brain Axis – PubMed (nih.gov) 
    3. Brain-gut-microbe communication in health and disease – PubMed (nih.gov) 
    4. The Second Brain – HarperCollins 
    5. The Simplified Guide to the Gut-Brain Axis – How the Gut Talks to the Brain (psychscenehub.com) 
    6. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems – PMC (nih.gov) 
    7. L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications – PubMed (nih.gov) 
    8. Tryptophan-kynurenine pathway is dysregulated in inflammation, and immune activation – PubMed (nih.gov) 
    9. The role of inflammation and the gut microbiome in depression and anxiety – PubMed (nih.gov) 
    10. Fatty acid–induced gut-brain signaling attenuates neural and behavioral effects of sad emotion in humans – PMC (nih.gov) 
    11. Indications for the use of probiotics in gastrointestinal diseases – PubMed (nih.gov) 
    12. Microbiota-Brain-Gut Axis and Neurodegenerative Diseases – PubMed (nih.gov) 
    13. Antibiotic exposure by 6 months and asthma and allergy at 6 years: Findings in a cohort of 1,401 US children – PubMed (nih.gov)
    14. Probiotics as an emerging therapeutic strategy to treat NAFLD: focus on molecular and biochemical mechanisms – PubMed (nih.gov) 
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