The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health

by Emeran Mayer

stressful life events generally spark the attacks.

When the brain

perceives such a threat, it signals the hypothalamus,

to crank up release of a critical stress molecule called corticotropin-releasing factor, or CRF for short, which functions as a master switch that sends the bra...

Between meals, a different pressure wave—the migrating

motor complex—serves as your gut’s housekeeper, sweeping out anything else your stomach couldn’t dissolve or break down into small enough pieces such as undissolved medications and unchewed peanuts.

generating enough pressure to crack a Brazil nut and sweeping undesirable microbes from your sma...

this housekeeping wave operates only when there’s no food left to digest in your GI tract—when you’re sleeping, for example—and it switches off as so...

enteric nervous system

50 million nerve cells

“second brain”

your emotional brain can mess up just about every one of those seemingly automatic functions.

Emotions impact not just the stomach, but your entire digestive

tract.

When subjects reacted with hostility and aggression, their colons contracted quickly, whereas when they felt hopeless, inadequate, or self-reproaching, their colons contracted more slowly.

our brains have at least seven emotional operating programs that direct the body’s response to

fear, anger, sorrow, play, lust, love, and maternal nurturance.

Our emotional operating programs are written in our genes. This genetic coding is, in part, inherited from our parents, and it is also influenced by events we experience early in life.

Once an emotional motor program has been triggered, its effects may linger for hours—or

secretion of CRF in the brain naturally peaks in the early morning hours, and gradually declines until midday. So in patients with cyclical vomiting syndrome, brain CRF would most likely reach unhealthy levels early in the morning.

Ninety percent of the signals conveyed through the vagus nerve travel from the gut to the brain, while just 10 percent of the traffic runs in the opposite direction, from the brain to the gut. In fact, the gut can handle most of its activities without any interference from the brain, while the brain seems to depend greatly on vital information from the gut.

What information is your gut reporting on that’s so vital?

sensors in your gut inform the enteric nervous system about everything it needs to know in order to generate the most ap...

Twenty-four hours a day, seven days a week, our GI tract, enteric nervous system, and brain are in constant communication.

recent research has shown that some of the same mechanisms and molecules that are involved in the taste experience are not limited to your mouth, but are also distributed throughout our gastrointestinal tract.

this is the case for the

bitter and swe...

recep...

these receptor molecules are located on sensory nerve endings and on the hormone-containing transducer cells in the gut wall

(such as the serotonin-containing cells

which puts them in a perfect location to participate in the ...

these plant-derived substances link us and our gut-brain axis closely to the diversity of plants around

us.

Some receptors, like those that sense for sweet food, play an important role in the way we metabolize our food. When our sweet receptors sense glucose (created when carbohydrates are digested) or artificial sweeteners, they stimulate the absorption of glucose into the bloodstream, and the release of insulin from the pancreas.

bitter taste receptors

may respond to metabolites produced by intestinal microbiota, and that alterations in these receptors as a consequence of high fat intake and fat-related changes in gut microbiota

In addition to the gut-brain communication channel involving the endocrine cells, there is another system involving our

gut-based immune system and the inflammatory molecules these immune cells produce, the so called cytokines.

Peyer’s patches,

is becoming clear that our gut is designed to do far more than just absorb nutrients.

Serotonin is the ultimate gut-brain signaling molecule. Serotonin-containing cells are intricately connected to both our little brain in the gut and to our big brain.

This gut-based serotonin-signaling system plays a key role in linking events in the gut related to food, intestinal microbes, and certain medications to the activity of our digestive system, and to the way we feel.

serotonin-containing nerves in the gut play a key role in regulating the peristaltic reflex, while clusters of nerve cells in the brain send their signals to most regions of the brain, exerting an influence over a wide range of vital functions, including appetite, pain sensitivity, and mood.

a constant stream of low-level, serotonin-related gut signals are being sent to our brain’s emotional centers, in response to intestinal contents rubbing against the serotonin-packed cells,

Even if these serotonin-encoded signals don’t enter our conscious awareness, this low-level serotonin release could affect our background emotions and influence how we feel, exerting a positive “tone” on our mood—which in turn could explain why so many people experience a sense of contentment and well-being around the ingestion of an enjoyable meal.

gut’s sophisticated surveillance system can actually analyze food’s nutritional content and, at the same time, extract the information needed for its optimal digestion.

gut’s intricate sensory system begins extracting this information the second the food enters our mouth—when

when taste receptors on our tongue and enteric nerves in our esophagus begin transmitting information about what we’re ingesting—and continues doing so until the food ends up in our colon.

signaling molecules called “gut hormones” or “gut peptides,”

evolved from simple on-off switches to a complex universal biological language that the trillions of microbes in our intestines use to communicate with our digestive system and even our brain.