While it may seem like common knowledge that the brain controls all of our body’s voluntary and involuntary actions, there is something to be said for the messages our body-more specifically our gut can provide our brain. Familiar turns of phrases such as “go with your gut” or “gut-wrenching” sensations have integrated into many areas of the cultural zeitgeist. Still, these phrases’ foundational message comes from a solid biological basis. Here we will examine some of the significant ways our “second brain” impacts our digestive physiology and its relationship to our mental health. 

Some of the most common symptoms of anxiety, depression, and chronic stress are “low appetite and weight loss or overeating and weight gain” and present as “digestive disorders…for which no other cause can be diagnosed.” These symptoms can progress into stomach aches, IBS, and acid reflux. In short, whether it be short or long-term stress or mild to severe anxiety and depression, it is evident that there is a significant physiological impact our mental health can have on our digestive system. 

This is because our gastrointestinal system can also be referred to as our “second brain.” The term “second brain” is composed of our enteric nervous system (ENS), central nervous system (CNS), autonomic nervous system (ANS), and the hypothalamic pituitary adrenal (HPA) axis. Our gastrointestinal area connects with information from our brain to the peripheral systems and vice versa. Specifically, the ENS is comprised of “two thin layers of more than 100 million nerve cells lining your gastrointestinal tract from [the] esophagus to rectum.” From here, the ENS controls systems to digestion, from enzyme release to breaking down foods to assist the absorption of nutrients in the bloodstream.4 It is noted that “changes in gastrointestinal transit can have profound effects on the delivery of important nutrients, mainly prebiotics and dietary fibers, to the enteric microbiota”,3 which in turn can affect the brain’s overall functioning.

In how this relates to mental health, it is found that not only do the messages from our brain and CNS transfer to our digestive system, but our “second brain” transmits messages to the brain on its own. From here, it has been suggested that not only can mental health symptoms such as anxiety, stress, and depression contribute to gastrointestinal distress, but this distress could not only be the product but the cause of mental health issues. There is evidence that the micro bacteria present in the gut “interact with [the] CNS by regulating brain chemistry and influencing neuro-endocrine systems associated with stress response, anxiety and memory function.” 3 While this barely scratches the surface of the microbiological system in play and how it relates to our brain and brain functioning, it can serve as another way to broaden our perspective on mental health and its significant impact on our body.

So, what does this mean for our mental health, and how do we manage the symptoms? As said best by Nina Gupta, M.D. from the University of Chicago medicine: 

“People experiencing chronic stress may also eat more or eat unhealthy foods with a higher amount of natural and artificial sugar that is poorly digested and causes GI distress. People may also smoke and drink more alcohol or caffeine than normal, which can cause symptoms.” 2

Many studies correlate the nutritional contents of our food and how it impacts our body’s overall functioning and subsequent mental health changes. However, this is not to say we should follow the latest diet fad, cut entire food groups out, or only eat the highest-quality, organic, “clean” foods. The body has many systems in place, including our liver, kidneys, and digestive system, to keep our body “detoxed” and running as smoothly as possible with most of what we eat. This post serves as a way to create a greater awareness of how we nourish our bodies and improve our relationship with ourselves. We encourage you to seek the guidance of your primary care physician or dietitian with what nutritional parameters to follow or what diet would work best for you. 

As the holidays come around, New Year’s resolutions start developing, and the subsequent toll travel and family can have on our mental health, there can be an additional stressor as to what we consume during this time. It is essential to remember that our body’s systems are in constant contact and will be the first to let you know if your diet is contributing to any additional physiological issues. In the meantime, eat what leaves you feeling balanced and see if there are subsequent increases in your mood and mental well-being by eating what makes you feel “happy.” Further information can be found in the sources below and by reaching out to your doctor, nutritionist, and other medical professionals.