The idea that the brain is separate from the rest of the body is a tempting one. It seems to sit all alone in its ivory tower known as the skull, separate from all that it controls. But new medical research shows that the brain not only signals to the other organs, it can in fact be controlled by other organs.
Look who’s talking now
The most notable of these is the gut, also known as the gastrointestinal or digestive tract. One of the newer fields in medicine, neurogastroenterology, focuses on the many interactions between the brain and the gut. This field looks at how the brain and gut talk to and influence one another. Problems in the gut can actually signal the brain and cause changes in sensory perception, mood, and thinking, while a stressed-out brain can cause difficulty with digestion.
So which of these comes first? Scientists aren’t sure yet, but a study from 2017 may offer some clues. UCLA researchers found that the bacteria that live in the gut, known as your microbiota, may help determine the size of brain regions involved in sensation. The study showed that differences in the bacteria that live in the gut correlate with the size of the sensory processing region of the brain in patients with irritable bowel syndrome (IBS). The study also found that the patients with IBS were more likely to have a history of childhood emotional trauma. It is possible that what happens early in life may change a person’s gut bacteria, which may then affect the size of certain brain regions.
Breaking it down
The gut contains nerve cells called neurons, just like the brain, so some medications targeted at the brain also affect the gut. Serotonin and GABA, two of the molecules used in the brain to signal happiness and calmness, are also produced in the gut. This is one reason why patients with IBS are sometimes prescribed antidepressants for their intestines.
“It’s important to recognize that many times when there’s inflammation in other areas of the body, it could be coming from the digestive system,” says Institute of Functional Medicine (IFM) educator Elizabeth Boham, MD, MS, RD. “All of the systems of the body are intertwined.”
Gut health is mental health
Since it seems that what happens in the gut may not stay in the gut, researchers are looking into the ways that supporting gut health may improve mental health. For instance, consuming fermented foods (like kimchi and sauerkraut) that contain beneficial bacteria known as probiotics may protect against social anxiety. There is also compelling evidence that such probiotics can alleviate depressive symptoms. Given their exceptional status, probiotics that affect the brain even have a special name: psychobiotics.
Caution is needed however. While some types of probiotics seem to help with anxiety and depression, other studies have found that different probiotics with other species of bacteria may make depression and anxiety worse. As of now, probiotics for depression and anxiety remain understudied, and not all studies find positive results. Still, the research is very promising.In the meantime, healthy eating may be good for both gut and brain — eating plenty of fiber, fruits, fermented foods, and vegetables is the safest way to improve your gut health and maybe your brain health too.