A gastroenterologist explains the connection between the gastrointestinal tract and the brain, and how diet and nutrition can be linked to mental well-being.
There is a powerful connection between our gut and our brain that is known as the “gut-brain axis.”
The gut, or the gastrointestinal (GI) tract, is constantly sending signals to the brain, telling us if we’re hungry, full, or time to use the bathroom. The axis runs the other way too: our mental health or emotional state can lead to physical sensations in the gut.
“For some people, their gut feels worse when they’ve got more going on, when they’re not sleeping enough, or when they’re preoccupied with various stressors,” says Dr. Benjamin Lebwohl, a gastroenterologist at NewYork-Presbyterian Columbia University Irving Medical Center.
“The gut is sometimes called ‘the brain in the bowel,” says Dr. Lebwohl. “This reflects the finding that we have a tremendous amount of neural activity originating from the gut.” Health Matters spoke to Dr. Lebwohl to learn more about the gut-brain axis and the gut’s role in our mental health.
Dr. Benjamin Lebwohl
What is the gut-brain axis?
The gut-brain axis is the universal phenomenon of a connection between the workings of the gut and the doings of our consciousness and our awareness.
We all have a gut-brain axis. Once food hits the stomach and before it heads out as a bowel movement — anywhere in between is the gut, or the gastrointestinal (GI) tract. The gut is also home to neurons that send messages to the nervous system. So there is this strong, two-way crosstalk that everyone has.
When the gut sends a message saying it’s time for you to go to the bathroom — that is your gut-brain access at work. In other situations, something makes us anxious or stressed, and we experience nausea or queasiness. In still other situations, environmental cues will affect our gut health. For some people, when they travel far from their home might not have a bowel movement for a few days because their gut is basically going on strike.
Is the gut-brain axis a relatively new discovery?
The notion that the gut has its own nervous system has been around for decades. A lot of this work was pioneered Dr. Michael Gershon, a professor of pathology and cell biology at NewYork-Presbyterian/Columbia, who wrote a book called The Second Brain, referring to our guts.
For example, after we eat, and as the particles go through us, we’re not feeling every single one of those contractions as food is broken down. Sometimes we might feel cramps or we might hear a stomach growling, but we generally don’t feel this activity that is actually happening all the time. The gut has its own nervous system and it’s always at work.
What are signs of a healthy gut?
A main sign of a healthy gut is when you’re not thinking about it too much. The gut sends progress reports to the conscious brain: for example, go to the toilet now, or there may be some gas coming, or that last meal that you ate wasn’t quite right.
These progress reports, while necessary, are not always welcome. So in many cases, no news is good news. A sign of a problem is when we get lots of progress reports, whether that’s discomfort, pain or bloating; the need to go to the toilet excessively; or feeling constipated.
While it’s important to be in touch with your body, there is such a thing as too much information. After you have a large meal, you’d love your gut to take care of it without giving too much feedback on how it went.
How are gut health and mental health connected?
The gut contains serotonin, which is a neurotransmitter chemical that affects one’s mood. Antidepressants often act on receptors for serotonin, and increasingly it is seen to be beneficial for mood. It turns out there’s a lot more serotonin in our gut than in our brain. So that in part explains this sort of emotional connection we might have with our gastrointestinal tract and why it’s important to maintain a healthy gut.
Having gastrointestinal problems can also take a toll on mental health in many ways. There is a broad array of GI conditions, from acid reflux and heartburn to irritable bowel syndrome, to conditions like Crohn’s disease and celiac disease.
When the gut malfunctions, it can result in a very unhappy host. You feel pain, cramping and the need to go to the bathroom, and those feelings can interfere with your quality of life and ability to function. Going out to eat, or on a date, can be stigmatizing and embarrassing for someone with a GI condition. Traveling and eating out can cause anxiety because, unlike a home-cooked meal, you’re not sure if an ingredient in the food may cause a flare up. Some people prefer to avoid social interaction, and that runs the risk of closing off aspects of life that are really important to us and our mental health.
What foods are best for a healthy gut?
It’s really important to have adequate dietary fiber. A sign of inadequate dietary fiber is when the bowl movement frequency slows. For dietary fiber, choose whole grains as opposed to refined grains — brown rice over white rice and, and whole wheat bread over white bread.
We believe that whole grains are good for the gut for a number of reasons. They take longer to digest (as compared to refined grains) and so they keep you feeling full for longer, instead of having you feel hungry again an hour after you eat. They also act as a nutrient source for the healthy bacteria that live in our gut, and we believe that having a diverse community of healthy bacteria keeps the gut functioning well.
There are other foods that can be helpful for the gut depending on the circumstance. For example, kiwi can be very effective for managing constipation.
Do you recommend taking probiotics for gut health?
There are still more questions than answers about the effectiveness of probiotics and how they should be used. Most probiotics are regulated by the Food and Drug Administration (FDA) as dietary supplements, which has a much looser regulatory standard. That said, they’re very popular, and the majority of people who take them don’t report side effects. A natural way to incorporate the theoretical benefit of probiotics is to consume yogurt regularly.
What are some other ways people can strengthen their gut health?
The most important thing anyone can do is be up to date with their screenings. In the GI world, that’s colorectal cancer screening, Everyone, even if they feel perfectly well, should have a colonoscopy typically starting at age 45, and sometimes earlier, depending on whether there is a family history of colorectal cancer.
It’s important to underscore that colon cancer is common – 5% of us will get it in our lifetime, and the most common symptom of early colon cancer is no symptom. That’s where screening comes in.
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