Mental Health May Depend on the Health of Your Gut Flora
November 12, 2015
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By Dr. Mercola
When it comes to your mental health, your behavior, and even your
mood, we tend to think that the brain is in charge. In reality, your gut
may be calling the shots. In the 1800s and early 1900s, it was thought
that wastes in your colon could produce infections that lead to
depression and psychosis.
Widely accepted for a time, mental-health patients were often treated
with colonic purges and bowel surgeries, but eventually this was
regarded as quackery.
Today, research is bearing out what the scientists of yesteryear were
already privy to – that your mental health is very much dependent on
the microbes in your gut. As Scientific American reported:1
"Scientists are increasingly convinced that the vast assemblage
of microfauna in our intestines may have a major impact on our state of
mind."
Your Gut Is Intricately Connected to Your Brain
In addition to the brain in your head, embedded in the wall of your
gut is your enteric nervous system (ENS), which works both independently
of and in conjunction with the brain in your head.
Your ENS contains 500 million neurons and is thought to be largely
responsible for your "gut instincts," responding to environmental
threats and sending information to your brain that affects your
well-being.
This communication between your "two brains" runs both ways and is the pathway for how foods affect your mood.
For
example, fatty foods make you feel good because fatty acids are
detected by cell receptors in the lining of your gut, which then send
warm and fuzzy nerve signals to your brain.
However, this gut-brain connection is far more than just comfort food or butterflies in your stomach. According to Scientific American:2
"The gut-brain axis seems to be bidirectional—the brain acts on
gastrointestinal and immune functions that help to shape the gut's
microbial makeup, and gut microbes make neuroactive compounds, including
neurotransmitters and metabolites that also act on the brain.
These interactions could occur in various ways: microbial
compounds communicate via the vagus nerve, which connects the brain and
the digestive tract, and microbially derived metabolites interact with
the immune system, which maintains its own communication with the
brain."
Germ-Free Mice Show the Importance of a Microbiome
So-called germ-free mice, which have no microbiome to speak of, have
altered behavior and brain function. In a study by John Cryan from the
University College Cork in Ireland, mice without microbes in their
intestines are unable to recognize other mice around them.
He believes that microbes may communicate with the brain and help us
be social, which in turn allows the microbes to spread to others.3 In addition, mice lacking gut bacteria
have been found to engage in "high-risk behavior," and this altered
behavior was accompanied by neurochemical changes in the mouse brain.4
When examining the animals' brains, the researchers discovered a
number of genetic alterations in the germ-free mice. According to The Guardian:5
"Brain-derived neurotrophic factor (BDNF) was significantly
up-regulated, and the 5HT1A serotonin receptor sub-type down-regulated,
in the dentate gyrus of the hippocampus.
The gene encoding the
NR2B subunit of the NMDA receptor was also down-regulated in the
amygdala. All three genes have previously been implicated in emotion and
anxiety-like behaviors.
BDNF is a growth factor that is essential for proper brain
development, and a recent study showed that deleting the BDNF receptor
TrkB alters the way in which newborn neurons integrate into hippocampal
circuitry and increases anxiety-like behaviors in mice.
Serotonin receptors, which are distributed widely throughout the
brain, are well known to be involved in mood, and compounds that
activate the 5HT1A subtype also produce anxiety-like behaviors."
Further, researchers have discovered that the absence or presence of gut
microorganisms during infancy permanently alters gene expression.
Through gene profiling, they were able to discern that absence of gut
bacteria altered genes and signaling pathways involved in learning,
memory, and motor control.
This suggests that gut bacteria are closely tied to early brain development and subsequent behavior.
These
behavioral changes could be reversed as long as the mice were exposed
to normal microorganisms early in life. But once the germ-free mice had
reached adulthood, colonizing them with bacteria did not influence their
behavior.6
Psychobiotics: A New Treatment for Mental Health
Cryan believes beneficial microbes could one day be used to treat
mental health problems in humans. He dubbed the compounds
"psychobiotics." He told Scientific American:7
"That dietary treatments could be used as either adjunct or sole
therapy for mood disorders is not beyond the realm of possibility."
Interesting research led by microbiologist Premsyl Bercik and
gastroenterologist Stephen Collins also found that when the intestines
of germ-free mice were colonized with bacteria from other mice, they
took on aspects of the donor's personality.8
Other research shows that women who had high prolonged fevers during pregnancy are more likely to have children with autism.
The
finding held up in mice, too, and the MIA (maternal immune activation)
mice were also found to have leaky intestines and abnormal microbiomes –
a common occurrence in children with autism as well.9
Of particular importance, when the MIA mice were treated with a microbe called bacteroides fragilis, their gut permeability was corrected and many of their behavioral symptoms went away. According to the researchers:10
"…these findings support a gut-microbiome-brain connection in a
mouse model of ASD [autism spectrum disorder] and identify a potential
probiotic therapy for GI and particular behavioral symptoms in human
neurodevelopmental disorders."
How the GAPS Diet May Help Autism and More
Research by pioneers such as Dr. Natasha Campbell-McBride also shows there's a profound dynamic interaction between your gut, your brain, and your immune system.
She has developed what might be one of the most profoundly important
treatment strategies for preventing and treating autism, as well as a
wide range of other neurological, psychological, and autoimmune
disorders—all of which are heavily influenced by your gut health.
Her findings show that children born with severely damaged gut flora are
at a significantly increased risk of vaccine damage, which may help
explain why some children develop symptoms of autism after receiving one
or more childhood vaccinations while others do not.
Autism
isn't the only potential outcome in this case. GAPS may manifest as a
conglomerate of symptoms that can fit the diagnosis of either autism, or
attention deficit hyperactivity disorder (ADHD), attention deficit
disorder (ADD), dyslexia, dyspraxia, or obsessive-compulsive disorder,
just to name a few possibilities.
Digestive issues, asthma, allergies, skin problems, and autoimmune
disorders are also common outgrowths of GAPS, as it can present itself
either psychologically or physiologically. It's critically important
here to understand that the gut flora your child acquires during vaginal
birth is dependent on your—the mother's—gut flora. So if your
microflora is abnormal, your child's will be as well. Hence, addressing
your gut health prior to, and during pregnancy, is essential.
The GAPS diet consists of easily-digestible foods that are dense in
nutrition, including fermented foods. In general, avoiding processed
foods and foods high in sugar/fructose is an essential component of a
gut-healthy diet, as sugar feeds harmful bacteria and throws your
microflora off kilter. For more information, please see my interview
with Dr. Campbell-McBride, below.
Probiotics Alter Brain Function in Adults
Much of the research on the gut-brain connection has been conducted
on mice, because we don't have "germ-free" humans around… however,
research has been conducted on adults with promising results. For
instance, women who regularly ate yogurt containing beneficial bacteria
had improved brain function compared to those who did not consume
probiotics.11 Specifically, they had decreased activity in two brain regions that control central processing of emotion and sensation:
- The insular cortex (insula), which plays a role in functions
typically linked to emotion (including perception, motor control,
self-awareness, cognitive functioning, and interpersonal experience) and
the regulation of your body's homeostasis
- The somatosensory cortex, which plays a role in your body's ability to interpret a wide variety of sensations
The fact that this study showed any improvement at all is remarkable, considering they used commercial yogurt preparations
that are notoriously unhealthy -- loaded with artificial sweeteners,
colors, flavorings, and sugar. Most importantly, the vast majority of
commercial yogurts have clinically insignificant levels of beneficial
bacteria. Clearly, you would be far better off making your own yogurt
from raw milk—especially if you're seeking to address depression through
dietary interventions. Keep in mind that some signs of depression
aren't widely known or may even be counterintuitive. Following are some
of the more subtle signs of depression to keep an eye out for:12
| Aggression or hostility |
Irritability |
| Withdrawing from those you love |
Extreme fatigue (mental and physical) |
| Seeking out an affair |
Lashing out or being very short-tempered |
| Perfectionism |
Inability to concentrate |
| Extreme guilt |
Self-medicating with alcohol, cigarettes, food, or other addictions |
How to Help Your Gut Flora Flourish
Your gut bacteria are vulnerable to your diet and lifestyle and can be harmed by:
|
Antibiotics,
unless absolutely necessary (and when you do, make sure to reseed your
gut with fermented foods and/or a probiotic supplement) |
Conventionally raised meats and other animal products, as CAFO animals are routinely fed low-dose antibiotics, plus genetically engineered grains, which have also been implicated in the destruction of gut flora |
Processed foods (as the excessive sugars, along with otherwise "dead" nutrients, feed pathogenic bacteria) |
| Chlorinated and/or fluoridated water, especially in a hot shower, which is worse than drinking it |
Antibacterial soap |
Agricultural chemicals |
In addition to avoiding the harmful aspects above, reseeding your gut
with beneficial bacteria is essential for maintaining proper balance
and achieving optimal physical and mental health. In light of this, here
are my recommendations for optimizing your gut bacteria.
- Fermented foods
are the best route to optimal digestive health, as long as you eat the
traditionally made, unpasteurized versions. Healthy choices include
lassi (an Indian yoghurt drink, traditionally enjoyed before dinner),
fermented grass-fed organic milk such as kefir, various pickled fermentations of cabbage, turnips, eggplant, cucumbers, onions, squash, and carrots, and natto (fermented soy).
Fermented vegetables,
in particular, are an excellent way to supply beneficial bacteria back
into our gut. As an added bonus, they can also a great source of vitamin K2 if you
ferment your own using the proper starter culture. We had samples of
high-quality, fermented organic vegetables made with our specific
starter culture tested, and a typical serving (about two to three
ounces) contained not only 10 trillion beneficial bacteria, but
it also had 500 mcg of vitamin K2, which we now know is a vital
co-nutrient to both vitamin D and calcium. Most high-quality probiotic
supplements will only supply you with a fraction of the beneficial
bacteria found in such homemade fermented veggies, so it's your most
economical route to optimal gut
- Probiotic supplement. Although I'm not a major
proponent of taking many supplements (as I believe the majority of your
nutrients need to come from food), probiotics is an exception if you don't eat fermented foods on a regular basis.
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