Mind Altering Microbes: How your gut microbiome may influence your mood

"I've got a gut feeling about this"

While we have certainly heard that appetite and digestion are controlled by the enteric nervous system  (also known as "the master control panel in your gut"), who would've thought that the gut might also control your emotions and mood?  It's no wonder the old sayings, like "I've got a gut feeling about this", "That movie was gut-wrenching", or  "Come on, gut it out!" ring so true.  In fact I'd venture to say when we are trusting our intuition we associate it with having a "gut feeling" about something.

From the research it is now clear that gut microbes have an affect on inflammation, pain, eating behaviors, food cravings, mood and other seemingly unrelated symptoms, such as depression or uncontrolled anxiety.  In addition, it is common for depression and anxiety to co-exsist with disorders such as IBS (irritable bowel disorder).

It goes both ways...

Yes, it's true!  Did you know the gut-brain axis provides a way of communicating both directions using signals, such as neurotransmitters, hormones and cytokines?  This means that your gut bugs actually talk to your brain to influence emotions.  Equally important the emotions you feel and neurotransmitters produced by the brain have a profound effect on the gut as well.  We know that dysfunction in this communication between gut and brain can lead to various diseases, including depression and anxiety.  Who knew that the composition of your gut microbes could play such a great role in your mood?  The next time you get angry at your spouse or are overcome with sadness making you want to curl up in bed you can simply say, "Don't blame me...It's my gut microbes's fault!"  and you may be right on target!

The human gut is populated by more than 100 trillion microbes, which means there is more bugs in your gut than cells in your body.   And the genetic material contained by microbes in your gut is 150X that of the genetic material from human origin.  Most experts agree we have more than 1000 different species in our gut and over 7000 different strains.  We know that as we are exposed to stress, chemicals, antibiotics, and toxins, the diversity of the microbiome decreases and we know that the less diverse or microbiome, the more susceptible we are to illness and disease.

A baby's colonization of the gut first occurs at birth with vaginal exposure to the mother's microflora.  Did you know that c-section baby's have gut microbes more akin to skin flora than gut flora after birth?  And some studies show that throughout the entirety of life, they may never regain the normal diversity of vaginally delivered infants.

These are just a few of the functions of these bugs residing in your gut:

• Development of your immune system function
• Assisting with bowel movements and gut motility
• Maintaining intestinal cell barrier integrity (keeping the the good stuff in and the bad stuff out)
• Aiding in digestion and absorption of specific vitamins and minerals
• Controlling fat absorption and distribution

Pathways involved in communication between the gut microbes and brain.

Microbes and Stress

What is increasingly clear is that there is bi-directional communication between our gut microbes influencing the central nervous system and brain... and the reverse; communication between our brain influencing microbial composition.   Did you know that stress affects the gut microbes, too?

These are the top 3 ways that chronic stress affects the gut:

1. Increases the levels of inflammatory cytokines (IL-6, TNF-alpha) which can changes gut microbe populations.
2. Increases permeability of the gut lining, which is linked to many autoimmune diseases  (Hashimoto's thyroiditis, lupus, rheumatoid arthritis, multiple sclerosis and many others).
3. Allows bacteria to cross over into the bloodstream where the bacterial coating (LPS) can trigger an intense inflammatory response in the body.

So how do the gut microbes contribute to anxiety and depression?

Here are some of the mechanisms by which the gut microbes influence the brain and emotions:

• Altered microbial composition: Both probiotic ("good guys") administration and harmful infectious bacteria ("bad guys") have both shown to have an effect on the brain and emotions.  One study showed supplementation with probiotics decreased anxiety.
• Immune Activation:  Bacteria in the gut have been shown to activate the immune system and increase production of harmful pro-inflammatory cytokines.   There are many studies showing a link between increase in certain cytokines and depression (see below if you want to read more)
• Vagus nerve:  This is one of the main controls of the parasympathetic system that calms our fight or flight response and allows our body to relax and feel calm.  Activation of the vagus nerve and release of acetyl-choline has been shown to have a profoundly calming and anti-inflammatory effect on the body.  Most of the effects of gut microbes on the brain and body have been shown to be dependent on vagal nerve activation.
• Tryptophan metabolism:  Tryptophan is an extremely important amino acid and the raw material needed to make serotonin (think "the happy neurotransmitter") by the body.  There is a pathway, called the kynurinine pathway that involves metabolism of tryptophan and accounts for nearly 95% of the stores of tryptophan in the body.  In the case of pathogenic microbial infections in the gut (bacteria, yeast, or parasites) this pathway may be activated and "steal" from your body's tryptophan stores.  This leads to depletion of serotonin stores and may result in insomnia and depression.
• Microbial metabolites:  Bacteria in the gut help produce bile acids and short chain fatty acids (SCFAs) which are essential for human physical and mental health.
• Neurometabolites: Crazy but true... bacteria have the ability to produce many neurotransmitters and metabolites that have direct action on brain and thought.   Did you know studies show microbes can even influence your food cravings?!
• Bacterial cell wall sugars:  Perhaps most fascinating of all, the outer coatings of bacteria contain sugar molecules that can directly signal immune and hormonal systems into action.  This is the mechanism thought to be responsible for the healthy effects of probiotics on the gut and brain.

The bottom line is there is a growing body of evidence that suggests gut microbes play a large role in regulation in behavior and brain chemistry and are relevant to development of depression and anxiety.

So perhaps the best antidepressant is a healthy whole food diet and a high potency probiotic to fuel a healthy gut microbiome!

Check out Part II - Six Simple Steps to Treat Depression

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Further Reading:

• Psychoneuroimmunology Meets Neuropsychopharmacology: Translational Implications of the Impact of Inflammation on Behavior
• Inflammatory Cytokines in Depression: Neurobiological Mechanisms and Therapeutic Implications
• Cytokine variations and mood disorders: influence of social stressors and social support
• Increased IgA and IgM responses against gut commensals in chronic depression: Further evidence for increased bacterial translocation or leaky gut
• Mind-altering microorganisms: The impact of the gut microbiota on brain and behaviour
• Stress and the Gut

Healthy Gut = Healthy You!

There is a microbial zoo living inside you, literally trillions of microscopic organisms―more than 10,000 different kinds of them―all co-existing with each other and you.

In fact they outnumber you ten to one and ninety percent of the genetic material, (DNA and RNA) in your body is not yours, it belongs to the bacteria that is located mostly in your gut, but some also live on your skin and even in your nose.

Exactly what those different life forms do has been the subject of some exciting research in recent years, and while a few of these organisms can sometimes wreak havoc with your system, the majority of these little "bugs" are good, helping you digest your food, stay protected from infections, and even keeping your immune system properly regulated to fend off autoimmune diseases like asthma, allergies, and diabetes.

The community of microbes living on and in your body is unique to you – like your fingerprints – and is now being regarded as a key contributor to your overall health.

More and more, science is finding that teeny tiny creatures living in your gut are there for a definite purpose. Known as your microbiome, about 100 trillion of these cells populate your body, particularly your intestines and other parts of your digestive system.

Although some of these bacteria can make you sick, the majority are good, and they work together as to aid your digestive system and keep you well. Beneficial bacteria, better known as probiotics, along with a host of other microorganisms, are so crucial to your health that researchers have compared them to "a newly recognized organ." We now know that your microflora influence your:

• Immune system function
• Brain development, mental health, and memory
• Obesity
• Genetic expression 
• Risk of diseases, including autoimmune disease, cancer, diabetes, and autism

According to the featured article in Time Magazine:

"Our surprisingly complex internal ecology has been a hot topic in medicine lately. Initiatives such as the Human Microbiome Project, an extension of the Human Genome Project, have been working tirelessly to probe potential links between the human microbiota and human health, and to construct strategies for manipulating the bacteria so that they work with us rather than against us.

...They've been linked to a range of nasty conditions, including obesity, arthritis, and high cholesterol. Now, two newer areas of research are pushing the field even further, looking at the possible gut bug link to a pair of very different conditions: autism and irritable bowel disease."

Most people, including many physicians, do not realize that 80 percent of your immune system is located in your digestive tract, making a healthy gut a major focal point in your efforts to achieve optimal health. In fact, the root of many health problems is related to an imbalance of intestinal bacteria.  

The beneficial bacteria in your gut has actually been found to help prevent allergies by training your immune system to distinguish between pathogens and non-harmful antigens and respond appropriately – and this may be one reason why they also appear so beneficial in conditions like allergies, asthma, and eczema

 Like it or not, the bugs in your gut have a lot to say about your health!  This is why I frequently test patients gut function for common complaints such as fatigue, migraines, mood disorders, depression, anxiety or insomnia, ecezma, allergies, asthma, autism, and even trouble with concentration & memory.  Getting the gut bugs back into proper balance is critical to your overall health and especially the health of your immune system.  The simplest way to jump start your overall health is pay attention to the gut...  Eliminate sugar and refined flours from your diet and add a high dose probiotic to you regimen.  You'll be well on your way to a happy and helpful intestinal "zoo"!

http://www.health.harvard.edu/healthbeat/the-gut-brain-connection
http://www.mercola.com/
http://www.metametrix.com/test-menu/profiles/gastrointestinal-function/dna-stool-analysis-gi-effects
https://wsunews.wsu.edu/pages/publications.asp?Action=Detail&PublicationID=32253&TypeID=1

Low SIgA and why it matters to your gut health!

What is SIgA?

IgA is a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract... it is your first line of defense on the mucosal lining and it makes up a majority of your entire immune system.

Some people have a genetic deficiency and present with low levels of SIgA and frequent infections.  Others acquire a low level after their intestinal tract becomes over-run with abnormal microbes.

SIgA helps to shape the composition of the microbes in your gut!

Extraordinary amounts of immunoglobulin A (IgA) are produced in your intestinal mucosa daily, it is known as SIgA and is secreted into the human gastrointestinal tract. SIgA production is driven largely in response to mucosal antigens (bugs or food) encountered by gut-associated lymphoid tissue (GALT).  It is clear that secretory antibodies are directed against at least two broad classes of antigens. The first is associated with enteric pathogens (the "bad guys" or infections) and their virulence factors, or things that the bugs secrete, like toxins.


The second broad class of antigens recognized by SIgA is associated with the intestinal microbes or commensal microflora (the "good" guys, like probiotics). In experimental animal models commensal bacteria are potent inducers of secretory antibodies; in humans, it is estimated that between 25 and 75% of intestinal bacteria are coated with SIgA.  This could explain why one of the most basic ways to improve levels of SIgA is to give a patient probiotics and saccromyces boulardii. 

There is also evidence from mice that secretory antibodies play an important role in shaping the composition of the intestinal microbiota, which in turn can influence your gut's defense against invaders and enhance resistance to the intestinal infections.
  
Profound Role in Intestinal Balance and Your Health

So because SIgA can neutralize the "bad guys" and shape the "good guys" SIgA plays a profound role in intestinal balance and health.  SIgA is the main immunoglobulin in mucus secretions. The intestinal cells produce about 2-3grams of SIgA every day!  And production tends to peak in childhood and start to decline after about sixty years old.

This is our first-line defense against gut pathogens like bacteria, food proteins, parasites, fungi, toxins and viruses. SIgA antibodies prevent micro-organisms, food proteins and cancer-causing substances from binding to the surface of absorptive cells. Effectively, they attach themselves to invading bugs and trap them in mucus to prevent them from going anywhere!

The antibodies also 'tag' foods as acceptable to the body and this suggests why low SIgA levels can be a factor in developing and progressive food allergy and intolerance. Intestinal permeability is also related since, if levels are low, repair of mucosal tissues can be compromised.  This is often referred to as Leaky Gut and can coexsist with low levels of SIgA.

Certain SIgA antibodies have been shown to directly quench bacterial virulence, whereas others help with uptake of SIgA–immune complexes by mucosal dendritic cells and result in down regulation of pro-inflammatory responses normally associated with pathogens and allergic antigens.

In fact it is becoming increasingly evident that human health is inextricably linked to the gut microbiota, intestinal homeostasis, and mucosal immunity. IgA is at the centre of this dynamic. 

Testing your SIgA

Secretory IgA is quite independent of blood IgA levels so just because one is normal, doesn’t mean the other is.   SIgA can be measured in different ways, including stool and saliva. Levels can turn out to be low or high. Stool measurements have traditionally been based on sample extractions from animal models – it is hard to ask a mouse to spit! Salivary samples provide a systemic overview of circulating SIgA.

Ongoing low levels can help to explain why people can’t shift an immune problem like allergies, chronic skin conditions or infections. It can also explain why they find it hard to get rid of a microbial infection, too. Celiacs and those with IBD can have low levels and chronic stress has a major effect on SIgA levels. Certain medications can lower levels – including anti-inflammatories.   Other factors  includeviral infections (like Epstein Barr viruses), poor nutritional status, food allergies, ongoing stress. Interestingly some studies have shown variations in levels with gender and age – male patients often have lower levels.

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