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| MAY/JUNE 2015
• Alternative Medicine
Are Probiotics
the New Antidepressants?
Over the years I've seen many patients with anxiety, brain
fog, and depression. Most had been overmedicating with
prescriptions like Prozac, Lexapro, or Zoloft long before they
came to me. Generally, these patients had experienced only
slight improvements or improvements that did not last.
The aforementioned drugs all fall into a category of
commonly prescribed antidepressants known as selective
serotonin reuptake inhibitors, or SSRIs. Most SSRIs lose
their effectiveness over time, which means psychiatrists
add other medications to the mix, including antipsychotics
(such as Abilify) or other "cocktail" drugs. These drugs often
cause weight gain, low libido, and sluggishness, which
make patients feel even worse.
here is a simple, natural,
and non-pharmacological solution to these
mood and brain conditions, however—and it
resides inside the gut. I often surprise
my patients by asking them, “How
is your digestion? Any gas, bloating,
nausea, bowel irregularities?” Their
responses range from laughing out loud
to curiosity or disbelief.
Problems in the brain often
originate in the gut and, particularly,
in the microbiome—the community
of trillions of bacteria that live in the
intestines and elsewhere in the body.
Even when there are no digestive
symptoms, the microbiome can be out
of balance—often leading to disastrous
consequences for our physical, mental,
and emotional health.
Although we’re used to thinking of
bacteria as dangerous, they’re actually
just the opposite: Bacteria are essential
to our health and, indeed, to our very
life. Sure, some bacteria are dangerous,
just as some are neutral. But the vast
majority are beneficial. And because
we co-evolved with them, our bodies
are literally unable to function without
them. Microbes enable us to digest our
food, support our immune system, and
process thought and emotion. They are
an integral part of our health and wellbeing. A balanced microbiome means
that you can think clearly, remember
accurately, and focus intently. It also
creates a calm, balanced mood with a
lot of emotional reserve for processing
stress. An unbalanced microbiome,
by contrast, often leads to brain fog,
anxiety, and depression—the ailments
that so many physicians are treating
with pharmaceuticals.
The Gut, Microbiome, and Brain:
A Powerful Triangle
Some of the most exciting research from the past few years
shows remarkable connections between the gut, microbiome,
and brain. The microscopic creatures living in our intestinal
lining produce a number of biochemical reactions that have
a profound effect on both our brain chemistry and on the
brain cells themselves.
An imbalanced microbiome activates the immune
system, which is adjacent to the microbiome in the gut wall.
Microbial imbalance also frequently erodes the gut wall
and leads to poor gut function. The whole process results
in intestinal permeability—aka leaky gut—a process by
which partially digested food leaks through the gut wall
and into the bloodstream. The immune system doesn’t
recognize food in this form, so it goes on alert, which creates
a constant, low-grade immune response. This is known
as chronic inflammation, and it can lead to a number of
chronic diseases, including obesity, diabetes, heart disease,
autoimmune conditions, and cancer.
Meanwhile, the excessive immune reaction also affects
the brain via the microglia—specialized immune cells found
in the brain. In a healthy condition, the microglia seek out
damaged neurons and infections and clear them from the
But when the microbiome is imbalanced, the microglia
produce cytokines, inflammatory messengers that can
seriously damage the brain. As a result, brain function is
altered. Anxiety, depression, and brain fog are the result.
You can significantly turn this situation around with
the use of probiotics—pills, powders, or capsules that
contain billions of healthy bacteria. Probiotics help restore
balance in your microbiome, while reducing inflammation
throughout your body and brain; they are a significant part
of my treatment of depressed, anxious, or “foggy” patients.
New research shows that probiotics raise your brain’s level
of IL-10, an anti-inflammatory cytokine that helps fight off
the inflammatory type in order to protect and support your
Another supplement that fights depression is butyrate, a
type of acid produced in the gut. A 2013 article in Behavioral
Pharmacology found that butyrate can be very helpful in
medicating depression—I’ve prescribed butyrate for many
of my patients, while simultaneously working to rebalance
their microbiome so that, eventually, the healthy and restored
microbiome could produce its own butyrate.
In a 2013 placebo-controlled, double-blind study
published in the journal Gastroenterology, researchers
observed the effect of probiotics on brain function. They gave
the female participants a fermented milk drink three times a
day; some women were given the drink plain, whereas others
had drinks supplemented with extra probiotics. When the
| MAY/JUNE 2015
• Alternative Medicine
women’s brains were examined via MRI, the probiotic group
showed changes in the midbrain region—the area involved in
emotional processing.
Similar research was published in 2007 in the European
Journal of Clinical Nutrition. In that study—also placebocontrolled and double-blind—subjects who were given
fermented milk with extra probiotics reported significantly
improved mood compared with the people who had just been
given the milk. I’ve seen these results in my own patients,
who indicate that probiotics and other microbiome supports
make them feel better with surprising speed.
Bacteria and Brain Chemistry
The microbiome does affect the brain—but our biochemistry
is so complex that we are only just beginning to discover
some of the many types of gut-brain interaction. The microbiome can alleviate depression and anxiety in four key ways:
Healthy bacteria produce key neurotransmitters, the biochemicals that express
mood. Serotonin, which creates a sense
of optimism, confidence, and well-being,
is produced by gut bacteria. So is gammaaminobutyric acid (GABA), which creates a
soothing sense of calm.
Bacteria produce a number of biochemicals
that improve brain function, mood, and
mental vitality.
Microbes send messages to the endocrine
system, supporting the HPA axis
(hypothalamus, pituitary, and adrenals).
This, in turn, modulates the body’s
production of cortisol and stress hormones,
which prevents anxiety and depression.
A healthy microbiome triggers the immune
system to send messages to the brain,
instructing it to decrease anxiety and
Individual studies reveal the powerful connection between
mood and microbiome. In 2007, for example, Nature
published an article about Lactobacillus acidophilus, a type of
bacteria found in yogurt, kefir (fermented milk), and many
other fermented foods. This common microbe stimulates
the brain’s opioid and cannabinoid receptors—the very same
receptors that are stimulated by opiates (painkillers, heroin,
and other drugs) and cannabis. So the next time you want a
natural high, reach for the yogurt—or better yet, the sauerkraut!
Two other friendly bacteria—Lactobacillus helveticus and
Bifidobacterium longum—have been shown to lower the stress
hormone cortisol, while also reducing anxiety. In a recent
double-blind, placebo-controlled random study, these two
bacteria were given to patients for 30 days. Patients reported
that their moods had improved by the power of bacteria.
Whereas fermented foods feed your healthy bacteria, a
diet high in refined carbs supports the unhealthy kind. This
diet has the potential to produce LPS, a compound that
inflames the microglia, among other ill effects. And inflamed
microglia, as we have seen, create brain fog, anxiety, and
Microbiome Medicine:
Psychiatry’s New Frontier
As a physician who has treated many patients struggling with
depression, anxiety, and brain fog, I believe that psychotropic
drugs and antidepressants are not the answer. Most antidepressants are blunt instruments—we don’t know exactly
how they will affect us, and they often produce a number of
unwanted side effects.
By contrast, the microbiome is a delicate, complex
set of tools that works to produce a range of benefits. It
seems to take advantage of its intimate knowledge of our
biology, neurology, immunology, and genetics, as well as
their staggering interconnections—our own natural antidepressant, if only we nourish and support it.
Probiotics are one way to support the microbiome,
and I rely on them heavily. But they are not enough. The
Microbiome Diet—a comprehensive approach to eating—is
crucial for feeding the friendly bacteria and starving out the
unfriendly ones.
Prebiotics are also useful. Whereas probiotics are actual
bacteria, prebiotics are the foods and supplements that
nourish friendly bacteria. I tell my patients that you can stock
a lake with new fish, or you can clean up the lake and feed the
existing fish. In most cases, it’s beneficial do both!
Today’s medical environment fails so many people
suffering from brain fog, anxiety, and depression. However,
microbiome medicine gives us an opportunity to offer hope
to millions by opening up a new frontier in treatment—and
the result might be a whole new world of brain health.
Raphael Kellman, MD, is a pioneer in functional medicine
who has a holistic and visionary approach to healing. He is
the author of The Microbiome Diet, Gut Reactions, and
Matrix Healing. Learn more at
Eight additional ways to
support your microbiome:
Be as careful as possible about avoiding
antibiotics; sometimes they are
necessary, but they always disrupt the
microbiome. If you must use them, make
sure to take probiotics at the same time.
Ask your doctor about discontinuing your
proton pump inhibitor, which reduces
microbial diversity; explore natural alternatives instead.
Ask your doctor about discontinuing
nonsteroidal anti-inflammatory drugs
(NSAIDs), such as aspirin or Motrin;
explore natural alternatives instead.
Eat organic as much as possible; industrial chemicals are not good for the microbiome.
Limit meat consumption, which destroys
many healthy bacteria. Instead, eat a lot
of high-fiber veggies, which will feed the
healthy bacteria.
Eat healthy fats to support gut
and microbial health.
Avoid concentrated fructose, especially
high-fructose corn syrup, which is terrible
for your microbiome.
Get a little dirty! If you play in the dirt
or eat unwashed produce—organic only,
of course—you expose your gut to some
additional friendly microbes that make
your microbiome healthier and more
diverse. MAY/JUNE 2015
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