It sometimes seems as if our gut has a mind of its own, and some would argue that’s because it does! For example, do you ever wonder what the culprit of your comfort food cravings is? Well, if you thought it was your brain, you were close—it’s actually your “second brain,” also known as the gut, or more formally, the enteric nervous system (ENS). The enteric nervous system is a complex network of nerves responsible for regulating digestion. To better understand your cravings and how to stave them off, you’ll have to get to know the “second brain” in your belly.
The enteric nervous system is a subdivision of the peripheral nervous system (PNS), and consists of about 500 million neurons (nerve cells) embedded in the lining of the gastrointestinal tract, starting at the esophagus and continuing all the way down to the anus. To put it in perspective, the enteric nervous system has five times as many neurons as the spinal cord!
Initially, experts thought the enteric nervous system solely took orders from the brain through nerves like the vagus nerve. For that reason, it used to be considered part of the autonomic nervous system. However, studies have found that even if the vagus nerve is severed, the enteric nervous system continues to function. In fact, the primary role of the vagus nerve is to send signals from the gut to the brain, not the other way around. This independence and complexity not only caused scientists to make the enteric nervous system a category all its own, but it also sparked an entire new field of research called neurogastroenterology.
The enteric nervous system’s responsibilities are many, but in the simplest terms, it regulates movement patterns along the gastrointestinal tract and maintains the biochemical environment necessary for digestion. More specifically, it controls gastric acid secretion, regulates blood flow and fluid movement, controls the pH, and interacts with the immune and endocrine systems. It sends information via the vagus nerve to the brain on the status of the digestive process.
Stress, Emotions and the ENS
The enteric nervous system has a significant influence over your emotions. For example, when you are stressed, the body’s natural sympathetic response causes blood flow to divert away from the gut, which can cause the sensation of “butterflies in your stomach.” You may not be conscious of why you’re nervous, but you have that “gut feeling” that tells you things just aren’t right. This gut reaction is picked up by the vagus nerve as a signal, which is passed along to the brain where the feeling is interpreted. Though decision-making is ultimately completed in the brain, the feelings in the gut may have a say over whether or not you ride that roller coaster or go on that second date.
Additionally, stress triggers an increased production of ghrelin. On the up side, ghrelin helps to ease anxiety and depression. However, it also is responsible for making you hungry. More specifically, ghrelin causes a craving for fatty foods. Ghrelin also stimulates the release of dopamine in the brain. Dopamine release is typically considered a pleasure and reward response. Evolutionarily, this made sense since our early predecessors may not have known exactly when their next meal was coming or what it would consist of. They needed fatty foods to survive. However, nowadays we have an abundance of fatty foods at our disposal at any given time (not to mention a population of people experiencing high amounts of stress, anxiety and depression). The unfortunate result is overeating and obesity.
So if the connection between reward and eating fatty foods is so ingrained in our nature, how can we live healthy lives? The answer is both simple and complicated: decrease stress. If you are less stressed, your enteric nervous system will produce less ghrelin, which is important for your health and waistline.
Some sources of stress in the body include work, commutes, relationships, poor diet, lack of sleep, and general health issues. To cope effectively with stress, you must identify and address the major sources of stress specific to your life. Of course, some sources of stress are easier to address than others. So start with small changes, like taking five minutes a few times a day to just focus on your breath or indulge in a good book. Over time, begin to address each of your stressors. Practice meditation and restorative yoga to help the body release tension and ease the sympathetic nervous system response to stress (fight or flight). The more time you spend in a calm state of mind each day, the easier it will be to return to that calm state when you experience stress. Since there are so many different sources of stress to address and juggle, you may find it valuable to meet with a wellness coach to design a plan of action for ridding your life of unnecessary stress.
The nervous system as a whole is highly interconnected. Therefore, ailments that affect any part of the nervous system will likely also have a negative impact on the enteric nervous system. However, there are a few ailments that specifically affect the enteric nervous system: intestinal aganglionosis, hyperganglionosis, hypoganglionosis, Crohn’s disease, ulcerative colitis, IBS, Parkinson’s disease, and Hirschsprung disease.