What you think is going on in your head may be caused in part by what’s happening in your gut.
A growing body of research shows the gut affects bodily functions far beyond digestion. Studies have shown intriguing links from the gut’s health to bone formation, learning and memory and even conditions including Parkinson’s disease. Recent research found disruptions to the stomach or intestinal bacteria can prompt depression and anxiety—at least in lab rats.
Better understanding the communication between the gut and the brain could help reveal the causes of and treatments for a range of ailments, and provide diagnostic clues for doctors.
The gut—considered as a single digestive organ that includes the esophagus, stomach and intestines—has its own nervous system that allows it to operate independently from the brain.
This enteric nervous system is known among researchers as the “gut brain.” It controls organs including the pancreas and gall bladder via nerve connections. Hormones and neurotransmitters generated in the gut interact with organs such as the lungs and heart.
Like the brain and spinal cord, the gut is filled with nerve cells. The small intestine alone has 100 million neurons, roughly equal to the amount found in the spinal cord, says Michael Gershon, a professor at Columbia University.
The vagus nerve, which stretches down from the brainstem, is the main conduit between the brain and gut. But the gut doesn’t just take orders from the brain.
“The brain is a CEO that doesn’t like to micromanage,” says Dr. Gershon. The brain receives much more information from the gut than it sends down, he adds.
Many people with psychiatric and brain conditions also report gastrointestinal issues. New research indicates problems in the gut may cause problems in the brain, just as a mental ailment, such as anxiety, can upset the stomach.
Stanford’s Dr. Pasricha and colleagues examined this question in the lab by irritating the stomachs of newborn rats. By the time the animals were eight to 10 weeks old, the physical disturbance had healed, but these animals displayed more depressed and anxious behaviors, such as giving up more quickly in a swimming task, than rats whose stomachs weren’t irritated.
Compared to controls, the rats also showed increased sensitivity to stress and produced more of a stress hormone, in a study published in May in a Public Library of Science journal, PLoS One.
Other work, such as that of researchers from McMaster University in Hamilton, Ontario, demonstrated that bacteria in the gut—known as gut flora—play a role in how the body responds to stress. The exact mechanism is unknown, but certain bacteria are thought to facilitate important interactions between the gut and the brain.
Electrically stimulating the vagus nerve has been shown to reduce the symptoms of epilepsy and depression. (One treatment approved by the Food and Drug Administration, made by Cyberonics Inc., is already on the market.)
Exactly why such stimulation works isn’t known, experts say, but a similar procedure has been shown in animal studies to help improve learning and memory.
Earlier this month, researchers made a small step toward understanding a gastrointestinal ailment that typically affects children with autism.
In a study of 23 autistic children and nine typically developing kids, a bacterium unique to the intestines of those with autism called Sutterella was discovered.
The results, published online in the journal mBio by researchers at Columbia’s school of public health, need to be studied further, but suggest Sutterella may be important in understanding the link between autism and digestive ailments, the authors wrote.
Dr. Gershon, professor of pathology and cell biology at Columbia, has been studying how the gut controls its behavior and that of other organs by investigating the neurotransmitter serotonin.
Low serotonin levels in the brain are known to affect mood and sleep. Several common antidepressants work by raising levels of serotonin in the brain.
Yet about 95% of the serotonin in the body is made in the gut, not in the brain, says Dr. Gershon. Serotonin and other neurotransmitters produced by gut neurons help the digestive track push food through the gut.
Work by Dr. Gershon and others has shown that serotonin is necessary for the repair of cells in the liver and lungs, and plays a role in normal heart development and bone-mass accumulation.
Studying the neurons in the gut also may also help shed light on Parkinson’s disease. Some of the damage the disease causes to brain neurons that make the neurotransmitter dopamine also occur in the gut neurons, researchers say.
Researchers are now studying whether gut neurons, which can be sampled through a routine colonoscopy, may help clinicians diagnose and track the disease without invasive brain biopsies, says Pascal Derkinderen, a professor of neurology at Inserm, France’s national institute of health.
“The mind has great influence over the body, and maladies often have their origin there.” — Moliere
What were Dean Ornish, Mehmet Oz, Dan Brown, the Dalai Lama, and I all doing in Woodstock, New York, last week?
We — along with an assortment of Tibetan monks and doctors, Buddhist scholars, meditation researchers, and prize-winning biomedical scientists in the field of aging, the immune system, stem cells, genetics, brain aging, stress physiology, and more from MIT, Yale, Harvard, Columbia, Duke, and UCSF — were all part of a special conference at the Menla Center.
The subject of this conference: Longevity and Tibetan medicine.
If that seems intriguing, it was!
The goal of the conference might sound complex — but it was quite simple.
We were there to investigate the relationship between the science of longevity and wellness and the ancient Indo-Tibetan practices of meditation and training the mind.
The point wasn’t to learn how to treat disease, but to learn what we know about regeneration of the body, protection from illness, and optimization of our function and wellbeing.
The convergence of “post-modern biology” — the new science of “systems” thinking and medicine — and the ancient wisdom and practices of Tibetan medicine and Buddhism was startling.
So what did we talk about?
Well, for one thing, we explored the relationship between the nervous system and health and aging, and the connection between the immune system and health.
As you get older, your immune system produces more inflammatory molecules, and your nervous system turns on the stress response, promoting system breakdown and aging.
That’s not just talk. It’s backed by scientific studies.
For example, Kevin Tracey, the director of the Feinstein Institute for Medical Research, discovered how the brain controls the immune system through a direct nerve-based connection.
He describes this as the inflammatory reflex (i). Simply put, it is the way the immune system responds to the mind.
Let me explain.
You immune system is controlled by a nerve call the vagus nerve.
But this isn’t just any nerve.
It is the most important nerve coming from the brain and travels to all the major organs.
And you can activate this nerve — through relaxation, meditation, and other ancient practices.
What’s the benefit of that?
Well, by activating the vagus nerve, you can control your immune cells, reduce inflammation, and even prevent disease and aging!
It’s true. By creating positive brain states — as meditation masters have done for centuries — you can switch on the vagus nerve and control inflammation.
You can actually control your gene function by this method. Activate the vagus nerve, and you can switch on the genes that help control inflammation.
And, as you know from my books Ultraprevention and UltraMetabolism, inflammation is one of the central factors of disease and aging.
But that’s not all we learned at the conference.
Even more fascinating was the discovery that our bodies can regenerate at any age.
Diane Krause, MD, PhD, from Yale University discovered that our own innate adult stem cells (cells that can turn into any cell in the body from our bone marrow) could be transformed into liver, bowel, lung, and skin cells. (ii)
This is a phenomenal breakthrough.
It means that we have the power to create new cells and renew our own organs and tissues at any age.
And how are these stem cells controlled?
You guessed it: the vagus nerve.
So relaxation — a state of calm, peace, and stillness — can activate the vagus nerve.
And the vagus nerve, in turn, activates your stem cells to regenerate and renew your tissues and organs.
Scientists have even shown how meditation makes the brain bigger and better.
They’ve mapped out the brain function of “professional meditators” by bringing Tibetan lamas trained in concentration and mental control into the laboratory.
The result? They found higher levels of gamma brain waves and thicker brain cortexes (the areas associated with higher brain function) in meditators. (iii)
Relaxation can have other powerful effects on our biology.
In biology, being a complex system that can adapt to its environment and that is resilient and flexible is critical to health.
The same is true for us.
The more complex and resilient we are, the healthier we are.
Take, for example, our heartbeat.
Its complexity is called heart rate variability (HRV) or beat-to-beat variability. The more complex your HRV, the healthier you are. The least complex heart rate is the worst — a flat line.
So what does this have to do with relaxation?
The HRV is also controlled by the vagus nerve.
As you can see, turning on the relaxation response and activating that vagus nerve is critical to health.
Let me review what we learned at the conference.
By learning to create positive brain states through deep relaxation or meditation, you can:
* Reduce inflammation
* Help regenerate your organs and cells by activating stem cells
* Increase your heart rate variability
* Thicken your brain (which normally shrinks with aging).
* Boost immune function
* Modulate your nervous system
* Reduce depression and stress
* Enhance performance
* Improve your quality of life
Not bad for just learning to chill out!
Think you’re too stressed out to relax?
Not so fast. We learned that it’s not always outside stressors that are the most important, but our responses to those stressors.
In fact, the Dalai Lama told a story of a Tibetan monk he met who had been in a Chinese gulag, where he was tortured, placed in solitary confinement, and prohibited from practicing his traditions for more than 20 years.
The Dalai Lama asked him what his greatest stress was.
The monk replied that it was his fear that he would lose compassion for his Chinese jailers!
I have met a number of these old monks, who spent the better part of their lives imprisoned and tortured. What is remarkable is that they didn’t suffer from post-traumatic stress syndrome — that they emerged intact, peaceful, happy, smiling, and giving back to the world.
Perhaps stress is more about the stories we tell ourselves about our lives.
On the other hand, the damaging effects of stress are clear.
As we learned at the conference, one of the leading theories of aging is that the protective ends of our DNA (called telomeres) shorten as we age.
Elizabeth Blackburn, PhD, who discovered telomeres, explained that, ultimately, they become so short that the end of our DNA unravels and we can no longer replicate our cells, so they die.
Remarkably, mental stress produces a more rapid shortening of the telomeres — and leads to faster aging.
What’s even more remarkable?
In a study of caregivers of sick patients, the health of the caregivers’ telomeres was determined by their attitude!
It sounds impossible, but it’s true.
The caregivers who felt the care to be a burden had shorter telomeres, while those who saw their work as an opportunity to be compassionate had no shortening. (iv)
In closing, the Dalai Lama said that the seat of compassion is actually biological and — necessary for survival.
Perhaps the development of compassion and wisdom in coping with unfavorable life conditions is the true key to longevity.
It just may be that working to understand our true nature through the cultivation of our minds and hearts with positive practices like meditation or similar techniques is critical to health and longevity.
The ways we can change our bodies through changing our minds is not longer a theory.
There is a new scientific language to understand how the qualities of the mind control the body through effects on the vagus nerve, immune cells, stem cells, telomeres, DNA, and more.
Remember, your body has all the resources and infinitely adaptable systems to self-regulate, repair, regenerate, and thrive.
You simply have to learn how to work with your body, rather than against it. Then you can have a healthy, thriving life — and live out your full lifespan, which can be as high as 120+ years!
So here are a few tips to activate your vagus nerve and prevent aging:
1) Learn to meditate.
Find a teacher or check out tapes or CDs [Practice the Éiriú Eolas Program!]
2) Stretch it out.
Try a yoga class in your area. Yoga can be a great way to release tension and deeply relax.
3) Get some energy.
Learn qi gong, a relaxing ancient system of energy treatment and balancing.
4) Get rubbed the right way.
Massage has been proven to boost immunity and relaxes the body deeply.
5) Make love.
The only way you can do it is if you are not stressed!
6) Get back to nature.
Climb a mountain and watch a sunrise, which will calm your nervous system.
7) Express yourself.
Write in your journal about your inner experience — this has been shown to boost immunity and reduce inflammation.
Now I’d like to hear from you…
Have you noticed how stress affects you?
Have you noticed people looking older after significant life stressors?
Have you noticed how people who seem to have a happy disposition or compassionate attitude toward life don’t seem to age as quickly as people who are angry and miserable?
Do you have any other suggestions for how to reduce stress, or better yet, how to better your manage your own response to stressful events?
To your good health,
Mark Hyman, MD
i Kevin J. Tracey, The inflammatory reflex, Nature 420, 853 – 859 (19 Dec 2002)
ii Krause DS. Plasticity of marrow-derived stem cells. Gene Ther. 2002 Jun;9(11):754-8. Review.
iii Lazar SW, Kerr CE, Wasserman RH, Gray JR, Greve DN, Treadway MT, McGarvey M, Quinn BT, Dusek JA, Benson H, Rauch SL, Moore CI, Fischl B. Meditation experience is associated with increased cortical thickness. Neuroreport. 2005 Nov 28;16(17):1893-7.
iv Epel ES, Blackburn EH, Lin J, Dhabhar FS, Adler NE, Morrow JD, Cawthon RM. Accelerated telomere shortening in response to life stress. Proc Natl Acad Sci U S A. 2004 Dec 7;101(49):17312-5. Epub 2004 Dec 1.