Bacteria & The Brain: The Powerful Behavior-Modifying Effects of The Gut
by Michael McEvoy Originally posted here.
The gut has been called "the second brain".
Research reveals that the enteric nervous system (ENS), a branch of the
autonomic nervous system that is found in the GI tract, can communicate with,
and function independently of the brain. The enteric nervous system of the gut
is comprised of about 500 million neurons. The enteric nervous system can
"think", "remember" and "learn" on its own
accord.
The enteric nervous system lines the mucosa of various
organs: esophagus, stomach, small intestine, large intestine, pancreas, gall
bladder, and biliary tree.
The ENS is involved in the regulation of several essential
digestive functions. Most notably:
- Peristalsis,
intestinal motility: bowel muscular contractions
- Digestive
enzyme secretion: to break down food particles
- Participates
in the regulation of esophageal muscles: moving food to your stomach
- Motility
of the gall bladder, releasing bile into the duodenum
- Assists
the hormone secretin in releasing pancreatic enzymes
- Exchange
of fluids and electrolytes in the gut
- Blood
flow through the gastric mucosa
- Also
involved in the regulation of the gastic and esophageal sphincters:
preventing acid food from entering the throat, and allowing food to pass
into the duodenum from the stomach
- Uses
more than 30 neurotransmitters, including serotonin, GABA, dopamine,
acetylcholine
Many researchers postulate that the enteric neurons have an
important role to play in regulating behavior. This is likely due to the fact
that the enteric nervous system communicates with the brain via the vagus
nerve. It is known that strains of intestinal bacteria have a powerful
regulatory effect on the enteric neurons. It is also known that these same
bacterial colonies can induce behavior-modifying effects.
In 2011, researchers from the Journal of
Neurogastroenterology stated: "As Bifidobacterium 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."
What this means is that behavior is directly linked to
intestinal bacteria and gut function.
Behavior & Leaky Gut
It is now well established that gut permeability, known as
"leaky gut" has a direct effect on behavior. Studies such as this have
demonstrated the link between intestinal permeability, gut infections and
depression.
A key mechanism with how intestinal permeability plays a
crucial role in behavioral disorders is most due to the effect that pathogens
and bacterial species have on brain and neurotransmitter function. For example,
streptococcal infections have shown to
cause symptoms of OCD (obsessive compulsive disorder), tics, and Tourette's.
Additionally, the immune response that is invoked from strep and other
infections, causes tremendous systemic inflammation, including to that of the
brain.
The outer casing of gram-negative bacteria, known as
lipo-polysaccharides (LPS), have shown in
studies to induce massive systemic inflammation, including the release
of pro-inflammatory cytokines such as TNF-a in the brain, as well as brain
microglial activation.
Because of the essential role of "tight junctions"
in the gut lining for protecting the organism from invading antigens, a
diminishment of the tight junctions leads to an increased level of
permeability, allowing various pathogenic microbes easy access into
circulation. This permeability of the gut wall induces high levels of
inflammatory activity in the brain, nervous system and in many other locations
in the body.
Additionally, leaky gut will also feature imbalanced gut
flora, and especially in the presence of pathogens and with an overgrowth of
opportunistic organisms. This may involve imbalances in the same gut bacteria
that communicate with the brain via the vagus nerve. So behavior and brain
function are affected by the gut in more than one way.
The Role Of Intestinal Flora In Modifying Behavior: Gut
Microbiome Axis
The intestinal flora makes up roughly 80% of the total
immune defenses of the body. The gut is lined with more than 100 trillion
micro-organisms, nearly ten times the amount of cells that make up the human
body. There are thought to be between 400-1000 different species of bacteria
that are normally found in the gut, and there exist intrinsic relationships and
complex communication networks among the bacterial species.
Immediately following birth, the act of breastfeeding
results in the implantation of essential floral colonies into the infant's gut. Studies have demonstrated that breast feeding
significantly reduces the risk of childhood asthma.Breast
feeding for more than 12 months has been shown to be protective
against the development of rheumatoid arthritis. One study found a correlation
between a shorter duration of breast
feeding and the development of ADHD in children.
Many recent studies have focused on the role that certain
probiotic strains have on regulating behavior. This is fascinating because it
shows the relationship between bacteria and the brain. The probiotic strain
bifido infantis 35624 has been studied for its role in possibly reducing
depression. Additionally, bifido infantis powerfully reduces IBS
symptoms.
Lactobacillus reuteri has been studied for its
anti-anxiety effects and for its powerful modulation of the immune system,
especially the inhibition of TNF-a.
Additionally, L-reuteri is
well established to modify the activity of the neurotransmitter GABA in the
central nervous system. The same is true for lactobacillus
rhamnosous.
L-helveticus and B-longum have been studied for effectively
reducing stress, anxiety and depression.
There are a plethora of additional studies that demonstrate
the role of gut microbes in regulating behavior.
Without a doubt, continual research will emerge that
identifies the intricate but profound role that bacterial balance in the gut
plays at modifying behavior.
Repair the Gut: Reduce Inflammation, Improve Cognition
Any serious health-improvement program should address the
function of the gut flora and mucosal barrier. This is magnified exponentially
if one has chronic gut issues, inflammatory conditions, autoimmune disorders,
and behavioral issues.
Because there are so many factors that will impede upon your
intestinal flora, maintaining proper digestion, assimilation and intestinal
immunity is paramount. All of these factors work together.
It is extremely common that when the gut is severely
compromised, the mucsoal barrier is damaged, and the "tight
junctions" that normally exist to keep pathogens at bay, are compromised.
If this is the case, there will most likely be a greater degree of inflammation
that can manifest at places in the body you wouldn't necessarily suspect (such
as the brain).
Often accompanying gut flora imbalances are food
intolerances of varying degrees. In fact, food allergies and sensitivities may
be amplified when one's gut flora is compromised. For some individuals
eliminating gluten, dairy and eggs may be essential. For others, low-oxalate
diets may be important.
In many instances, it may take years of persistent attention
to the gut before long-term results are achieved.
It is the opinion of this author, from firsthand experience,
that proper, individualized nutrition is the foundation for restoring the
function of the gut mucosal barrier.
Michael McEvoy has a private nutritional consulting
practice. He works with clients nationally and internationally. Please contact him to
learn more about his nutritional consulting services and programs.
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British Journal of Nutrition (2011)Michae ̈l Messaoudi1*,
Robert Lalonde2, Nicolas Violle1, Herve ́ Javelot3, Didier Desor4, Amine
Nejdi1, Jean-Franc ̧ois Bisson1, Catherine Rougeot5, Matthieu Pichelin6,
Murielle Cazaubiel6 and Jean-Marc Cazaubiel6: "Assessment of
psychotropic-like properties of a probiotic formulation (Lactobacillus
helveticus R0052 and Bifidobacterium longum R0175) in rats and human
subjects"
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2982.2011.01796.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false
