But what's the big deal?
It's just your gut, right?
Actually, the gut is a lot more important than you think it is, in that yes, it functions to help us digest what we consume, but more extraordinarily, it participates in a mutual interaction with our sympathetic/parasympathetic nervous system as well as our brain that can affect not only the way that we digest (or rather the quality of our digestion), but also the way we feel physically, mentally, and emotionally.
It's pretty cool. But how does it work?
The mechanisms of the gut can be altered by the brain, and the brain can also be altered by the mechanisms of the gut.
Let's start with the influence of the brain on gut health. When we are in a high-stress state, we are said to be in sympathetic mode, meaning our bodily functions perform in such a way as to allow us to most effectively respond to the stressor. This includes dilation of the pupils, constriction of the blood vessels, increase in heart rate, decreased production of digestive fluids, and decreased gut activity. This means that if you're in a high-stress state for prolonged periods of time, your gut will not be functioning optimally since your body is trying to "perform", or feels that it is in the flight-or-fight response 24/7, and by inhibiting gut activity, your body can respond to the stressor more effectively. No wonder so many Americans have digestive issues, given the high-stress state in which we are constantly living, with everything from work to school to obligations. The American hustle culture is the gut microbiome's worst nightmare!
In contrast, if we are in a low-stress state, we are in parasympathetic mode, which causes the pupils to constrict, the blood vessels to dilate, the heart rate to increase, digestive fluid production to increase, and gut activity to increase. This is why it's so, so, so important to figure out ways to manage your stress daily so that you can be kind to yourself and to your gut, because digestive issues are serious business.
So now you see how the brain can influence the gut, but how can the gut influence the brain?
Aside from the fact that your mood tends to be better when your digestive system is on point and worse when it's less than optimal, healthy bacteria in the gut has been proven to alter one’s mood, and a gut bacteria imbalance has even been linked to conditions such as anxiety, depression, Alzheimer's, and Parkinson's. The gut has its own communicative system called the enteric nervous system (ENS), which consists of about 100 million nerves lining the gut. I guess that's why the phrases "you've got guts" and "you've got a lot of nerve" are so interchangeable! The gut communicates to the brain via the vagus nerve, which is one of the major nerves bringing information to the brain from all over the body. So basically, the gut and the brain are true homies, so closely linked that they influence each other in profound ways. This has been shown in various studies in which the bacteria found in anxious animals' guts have been replaced with calmer animals' bacteria and vice versa, producing an exchange in anxiety levels between the two that corresponds with the type of bacteria found in the gut (good bacteria balance = good mood, dysbiosis = not so good mood).
I don't know about you, but a smoothly running digestive system and a happy brain sounds like a pretty freakin' nice existence to me, so gut health has really become a priority for me. Stay tuned for part two. Next week, I'll teach you how to improve your gut health, and how I've improved mine.
The sources below will show you more about why the gut is a much more vital part of your health than you think.
San Diego State University, Foods and Nutrition Major. Freshman.