Hippocrates, the Greek physician considered the founding father of medicine, once said that all disease begins in the gut, and anxiety disorder is no exception. Did you know that your gut bacteria can influence your mood? Read on to learn how the gut and brain communicate with each other, the evidence connecting the gut microbiome and anxiety, and how to fix gut dysbiosis.
Gut bacteria and the relationship with the brain
More and more people suffer from an anxiety disorder, characterized by apprehension and fear that can negatively affect productivity, personal relationships and quality of life in general. Pharmaceutical treatments, such as selective serotonin reuptake inhibitors (SSRIs) and benzodiazepines, manipulate neurotransmitter levels in the brain.
Although these medications provide relief for some, they are often ineffective and can have serious side effects.
Even if chemical imbalances were present in most people with anxiety (they are not), anti-anxiety medications fail to address a lesser-known contributor to depression, anxiety, and other mood disorders: intestinal dysbiosis. and dysfunction.
The brain and gut communicate through a gut-microbiome-brain axis, and a growing body of literature indicates that an altered gut microbiome can contribute to a variety of cognitive and mood disorders, including:
· Parkinson's disease
· Alzheimer disease
· Sensory processing disorder
· Obsessive compulsive disorder (OCD)
The bacteria in our gut have immense power over us, they can even influence our response to stress.
How the brain and gut communicate
The brain and gut can interact directly through the vagus nerve, which connects the central nervous system with the heart, lungs, and digestive tract. The vagus nerve can be activated by many neuroactive molecules found in the intestine.
Some species of gut bacteria synthesize neurotransmitters, including GABA, serotonin, and dopamine, and neurotransmitter modulators, such as brain-derived neurotrophic factor, or BDNF.
In fact, more than 90 percent of the body's total serotonin and more than 50 percent of the body's total dopamine are synthesized in the gut, not the brain.
Short chain fatty acids (SCFA)
Gut bacteria break down dietary fiber into anti-inflammatory short-chain fatty acids (SCFA). SCFAs stimulate the sympathetic and autonomic nervous system with neurological benefits. One example is butyric acid, which has been shown to slow the progression of Parkinson's and Huntington's diseases in animal models.
Thyroid and sex hormones
The gut microbiota is involved in the release and breakdown of hormones such as insulin, glucagon, leptin, and estrogen.
Other signaling molecules
Neuroendocrine cells comprise about 1 percent of the cells along the protective intestinal lining, called the epithelium. These cells release more than 20 neuroactive signaling molecules, including neuropeptide Y, oxytocin, ghrelin, and the calcitonin gene-related peptide.
Gut bacteria influence the brain throughout life. In the early stages of life, bacterial colonization of the intestine is crucial for proper brain development.
Germ-free mice, which do not have microorganisms in their intestines, experience abnormal mental development and develop defects in the structure of the brain. Altering the gut microbiota with antibiotics or probiotics can damage or improve memory, further supporting the gut's role in brain function.
We also have evidence that gut bacteria regulate pain perception, affect the protective coverings of the nerve sheath called myelin, and influence neuroplasticity, the brain's ability to reorganize and reconnect from good and bad inputs.
Due to the active gut-microbiome-brain axis, the stability and diversity of the gut microbiome can influence anxiety and other mood disorders. Let's look at some of the evidence supporting the gut microbiome and the anxiety connection.
Gut bacteria determine how the body responds to stress
A healthy gut promotes a normal response to stress through the hypothalamic-pituitary-adrenal (HPA) axis. The gut microbiota is essential for the development and function of the HPA axis, and there is a critical developmental window when colonization must occur for the HPA axis to function normally
Germ-free mice exhibit an exaggerated response to HPA stress, a hallmark feature of anxiety, indicated by excessive secretion of corticosterone and adrenocorticotropic hormone. The exaggerated response can be reversed by administering probiotics, but only in young mice. On the other hand, pathogenic E. coli made the condition worse.
As the gut microbiota mediates the stress response, stress can, in turn, alter the gut microbiota. It is a two-way street.
In mice, stressors such as maternal separation early in life or prolonged restriction induce significant changes in the intestinal bacterial profile.
In humans, intestinal stress changes have been reported, although specific bacterial changes are not always consistent between studies. Most likely, a person's individual response depends on their gut microbial diversity, gut wall integrity, diet composition, and general health.
Happy gut, happy person
Differences in gut bacterial compositions have been found in both animals and humans with mood disorders. In mice, depression and anxiety are accompanied by altered gut profiles.
Similarly, several human studies have found microbiota differences between patients with anxiety and / or depression compared to healthy control groups.
In a small study, lower levels of a particular bacterial genus, Faecalibacterium, were correlated with more severe depression.
Gut dysbiosis can cause anxiety, and resetting the gut microbiota can mitigate anxiety-like behavior. After pathogenic infection with the bacteria Campylobacter jejuni or Citrobacter amalonaticus, the mice developed anxious and abnormal behaviors, possibly through activation of the amygdala, a region of the brain that is often implicated in anxiety.
Similarly, germ-free mice exhibit anxiety-like behaviors. Probiotic supplementation has been shown to decrease anxious behavior in several mouse studies.
Interestingly, in another study, mice given oral antibiotics showed altered fecal microbiota, increased anxious behavior, and increased expression of BDNF in the hippocampal region of the brain, all of which resolved within a few weeks of stopping the antibiotics.
When germ-free mice were administered antibiotics, no changes in behavior or expression of BDNF were observed, indicating that the gut microbiome was indispensable for these alterations.
In this same study, researchers performed fecal microbiota transplants between two strains of mice with known behavioral differences.
When the more shy and anxious type of mice were colonized with microbiota of the less anxious type, the mice increased their exploratory behavior and showed a decrease in anxiety.
Conversely, when the less anxious mice were colonized with microbiota of the more anxious type, the mice decreased their exploratory behavior.
Of note, these behavioral changes were not accompanied by changes in neurotransmitter levels in the brain, further demonstrating that anxiety and other mood disorders have influences beyond the brain.
How to fix intestinal dysbiosis
A healthy gut must have a diverse, stable and robust microbiome with high integrity of the intestinal lining. Unfortunately, many factors present in our modern society contribute to intestinal damage:
· Overuse of antibiotics
· Inflammatory foods like refined sugars, refined carbohydrates, and industrial seed oils.
· Inadequate fiber
· Chronic stress
· High alcohol consumption
· Cesarean delivery and formula feeding
Our 21st century microbiomes are significantly less diverse than those of our ancestors, as are the microbiomes of modern hunter-gatherers who largely adhere to their traditional diets.
We have a lot to learn about the ideal makeup of the human microbiome, and just as there is no ideal diet, there is probably no ideal microbiome.
Right now, it's hard to get non-invasive snapshots of your microbiome throughout the entire GI tract. Fecal tests are common, but what is in the stool is not representative of the entire tract. Gut bacteria populations change and become denser throughout the digestive tract, with the distal colon (the latter sections) being the most densely populated.
However, if you suffer from mood disorders, such as anxiety, or a host of other conditions such as eczema, obesity, and gastrointestinal disorders, healing your gut might bring you some relief. Get started with these steps:
1. Treat any pathogens that may be present. The following recommendations (eating fiber, bone broth, and fermented foods) will only go a long way if you have an underlying, untreated infection.
2. Eat more fiber. Fiber feeds the microbiome, and low-fiber diets reduce microbial diversity. Consider a prebiotic supplement.
3. Drink bone broth. Bone broth and other sources of collagen and glycine can repair intestinal integrity.
4. Eat naturally fermented foods like natto, sauerkraut, kefir, yogurt, raw milk, and kim chi.
Will probiotics help your gut microbiome and anxiety?
The researchers coined the term "psychobiotics" to describe probiotic strains with the potential to affect psychological health. Several human clinical trials have shown that taking probiotics can reduce stress, improve sleep quality, and improve memory.
Specifically, Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, and Bifidobacterium longum have improved their anxiety and / or depression scores in human clinical trials. However, not all clinical trials with probiotics have been effective for mood disorders.
If you've tried the tips above and still have gut problems, probiotic supplements could make a difference. There are a dizzying number of probiotic supplements on the market, but Mark Ruscio classifies them into five main varieties:
· Saccharomyces boulardii (healthy mushroom)
· Soil-based or spore-forming probiotics
· E. coli Nissle (healthy form of E. coli)
Since it will take a few weeks to notice a difference, finding the most beneficial probiotic supplement could be a process of trial and error.
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