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  • Joan Rothchild Hardin

Psychobiotics: Your Gut Bacteria – Your Mood


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Very good news! An exciting new field of medicine is on the horizon: PSYCHOBIOTICS. PROBIOTICS are micro-organisms that have beneficial effects on the body when consumed. Ted Dinan, Catherine Stanton, and John Cryan, pioneering researchers in the field, define a PSYCHOBIOTIC as “a live organism that, when ingested in adequate amounts, produces a health benefit in patients suffering from psychiatric illness”. (Dinan, Stanton & Cryan, 2013)

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Scientists are discovering that some probiotic micro-organisms living in our guts are also psychoactive. That is, they deliver neuroactive substances such as gamma-aminobutyric acid (GABA) and serotonin that influence the brain via the gut-brain axis. I’d say that the field of psychobiotics in the not so distant future will be understood more broadly to include all of us, not just those with diagnosable mental illnesses. For example, we’ll be able to fine tune our anxiety levels day to day – by taking particular probiotics before events we know make us anxious (public speaking, flying, big dates, exams). And, even better, we’ll be able to AVOID depression’s deep troughs of despair and the exhausting paralysis of anxiety by nourishing healthy populations of the appropriate probiotics in our guts.

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As we understand the gut-brain axis at this point, communications between the gut and the brain (and vice versa) travel via the long vagus nerve, spinal cord, and/or neuroendocrine systems to mediate various physical and mental states – including anxiety, depression, obsessive-compulsive thoughts and behaviors, autism, chronic fatigue syndrome, and irritable bowel syndrome. Here’s a diagram of the vagus nerve’s path, showing the organs it connects between the brain at its top end and the intestines at its bottom end. You can see what an important communication highway it provides for the body, allowing the brain, lungs, heart, spleen, liver, kidneys, pancreas, stomach, and intestines to ‘talk’ to one another. THE VAGUS NERVE It runs from the brain stem down each side of the neck, across the chest, down through the abdomen allowing the brain, lungs, heart, spleen, liver, pancreas, kidneys, stomach and intestines to communicate bi-directionally along its network.


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“So far, psychobiotics have been most extensively studied in … patients with irritable bowel syndrome, where positive benefits have been reported for a number of organisms including Bifidobacterium infantis. Evidence is emerging of benefits in alleviating symptoms of depression and in chronic fatigue syndrome. Such benefits may be related to the anti-inflammatory actions of certain psychobiotics and a capacity to reduce hypothalamic-pituitary-adrenal axis activity. ” (Dinan, Stanton & Cryan, 2013) Did you notice the mention of the anti-inflammatory actions of probiotics in the quote above? Most physical and mental diseases have inflammation as their root cause. The vast majority of our immune system, about 70% of it, is located in the gut microbiome. Unbalance in the composition of microbes there creates inflammation inside the intestinal linings, increasing gut permeability, leading to chronic inflammation elsewhere in the body – and disease. This is my short hand explanation for how the connection works: Chronic imbalance of microbes in the gut –> chronic inflammation in the gut –> increased gut permeability –> chronic inflammation elsewhere in the body –>  diseases in the gut and/or elsewhere in the body

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These signaling irregularities affect our emotions, mental abilities, behaviors, and perception of and reactions to pain (nociception). The whole system is something like an enormous, highly complex switchboard. If something interferes with signaling somewhere in the system, a circuit can malfunction and perhaps cause the entire switchboard to break down.

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Chronic imbalances in our gut bacteria that lead to gut-brain axis signaling irregularities can also lead to a wide variety of other health problems – including diabetes, heart disease, stroke, migraines, thyroid problems, dental issues, cancers, degenerative neurological diseases, obesity, ADD/ADHD, allergies, asthma, autism, rheumatoid arthritis, chronic Lyme disease … and many, many more. And they all begin with the health of the several pounds of miniscule critters living in our gut microbiomes.

Our gut microbiome, the 100 trillion micro-organisms (500-1,000 species of bacteria, fungi, viruses, and other tiny life forms) living in our intestinal linings, is so important to the proper functioning of the entire body that many scientists now regard it as an organ in and of itself. The theory is that these micro-organisms  communicate with the nervous system using some of the same neurochemicals the body uses to relay messages in the brain. (Smith, 2015) These several pounds of micro-organisms in our guts secrete a large number of neurochemicals, including dopamine, serotonin, and gamma-aminobutyric acid (GABA), the very same chemicals our neurons use to communicate and regulate mood – and chemicals that also play a role in GI disorders, which, not strangely, are associated with high levels of depression and anxiety.  (Smith, 2015)

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ANXIETY, OBSESSIVE BEHAVIOR, LEAKY GUT AND BACTEROIDES FRAGILIS

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In 2013, microbiology researchers Mazmanian and Hsiao published research results that linked a specific variety of probiotic bacteria with anxious behaviors in mice. The mice were known to have alterations in their gut microbiota and GI barrier defects  (increased gut permeability, AKA leaky gut) and also exhibited anxious, obsessive behaviors (such as obsessively burying marbles). When they were given oral doses of  one of two strains of the bacterium Bacteroides fragilis (probiotic bacteria found in normal gut flora), both their GI problems and maladaptive behaviors improved. (Hsiao et al, 2013) (Smith, 2015) STRESS, DEPRESSION AND THE PROBIOTICS LACTOBACILLUS AND BIFIDOBACTERIUM

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A recent study found that a combination of the probiotics Lactobacillus helveticus and Bifidobacterium longum (probiotic bacteria found in healthy human gut microbiomes) reduced anxiety, depression, and stress levels and improved coping strategies. (Messaoudi, 2011) Our psychological and physiological reactions to fear and stress play a large role in depression. People suffering from major depression also have elevated levels of cortisol, the stress hormone our adrenals release to get us ready to fight for our lives or flee from the danger. Back when we frequently encountered predatory animals and were often in a fight or flight situation, this elevated release of cortisol was a very useful thing. What often happens now is that we live in a state of chronic cortisol overproduction, over stimulated, afraid, unable to calm down, wearing out our adrenals. Chronically elevated cortisol production interferes with learning and memory, lowers immune functioning, decreases bone density, increases weight gain,  raises blood pressure and cholesterol levels, leads to heart disease, increases risk for depression and anxiety, decreases resilience – and is generally exhausting. A combination of the probiotics, Lactobacillus helveticus and Bifidobacterium longum, was found to reduce cortisol levels. (Berglund, 2013) (Davidson, 2014) GABA (gamma-Aminobutyric acid) is our central nervous system’s chief inhibitory neurotransmitter, playing a central role in reducing neuronal excitability throughout the body and regulating muscle tone. (Wikipedia, 2015) Many physiological and psychological processes associated with depression, including negative ruminations, can be traced to a deficiency in the neurotransmitter GABA. Microbes that actively secrete GABA in the gut have been identified by researchers. Chief among them are strains of Lactobacillus and Bifidobacterium. Bifidobacterium longum has anti-inflammatory, anti-carcinogenic, and antimutagenic properties and may protect you from developing colon cancer.  It’s present in breast milk and is one of the first probiotics to colonize a newborn’s gut. Emmenthaler Cheese

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Swiss and Emmenthaler cheeses contain Lactobacillus helveticus. (We’re talking about real cheeses, not the tasteless, processed kinds often found prepackaged in the US.)

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Bifodobacterium longum is found in unprocessed yogurts, various types of fermented dairy foods (kefir’s a good choice), and fermented vegetables such as sauerkraut.

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Good news for those of us who love dark chocolate: The plentiful polyphenols in dark chocolate serve as PREbiotics, nourishing the beneficial Lactobacillus and Bifidobacterium  in our guts.  (Davidson, 2014) The higher the cacao and lower the sugar content the better. Organic and fair trade also if possible. Both L. helveticus and B. longum can also be taken as supplements. MOOD, OXYTOCIN AND LACTOBACILLUS REUTERI

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A team of biologists at MIT found that another probiotic strain, Lactobacillus reuteri, improved mood, restored a youthful appearance to the skin, and promoted general health by increasing levels of oxytocin, the love hormone. (Davidson, 2015) L. reuteri is one of the fastest colonizing probiotic bacteria available. This is a good thing – colonizing probiotic strains of bacteria in your gut can restore your health. ANXIETY, DEPRESSION AND LACTOBACILLUS RHAMNOSUS (Davidson, 2014) (Mercola, 2011) (Saey, 2011)

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Lactobacillus rhamnosus is a bacterial strain that has been shown to reduce anxiety and depression in anxious mice. GABA, the central nervous system’s principal inhibitory neurotransmitter, regulates many physiological and psychological processes in the body. Alterations in GABA receptor expression are linked to the development of anxiety and depression. Study results published in 2011 shed light on exactly how L. rhamnosus in the gut impacts the brain’s chemistry. The researchers found that the probiotic L. rhamnosus markedly affected GABA levels in certain brain regions and lowered the stress-induced hormone corticosterone, resulting in reduced anxiety- and depression-related behavior. When the vagus nerve was severed, 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 the gut and the brain. The researchers allow that the vagus nerve is the obvious communication route but perhaps not the only one, that messaging may also occur via other nerves or chemicals in the blood. If you doubt there’s a direct connection between the health of the gut microbiome and mental health, keep in mind that functional bowel disorders and mood disorders such as anxiety and depression are generally comorbid (they generally occur together). Strains of L. rhamnosus  are found in some dairy products such as live culture yogurts, cheeses (eg, real Parmigiano Reggiano), and kefir. They’re also found in fermented dry sausages and some fermented soy cheeses. (Panyko, 2015) PAIN, CHRONIC FATIGUE, DEPRESSION, ANXIETY AND LACTOBACILLUS ACIDOPHILUS