Gut-Brain Connection – Medical Update

By: Dr. Caroline Leaf
We all have to eat to live, as redundant as that statement may sound. Yet the act of eating is not just a biological function of survival. The consumption of food, as normal as it is, is in fact a highly emotional and metacognitive event. Indeed, this should come as no surprise to us: throughout human history, gathering around a table and eating food has been a way for us to celebrate or commemorate notable seasons, individuals and events. Meals are a focal point for social gatherings, and sharing food is a powerful medium of communication both in-between cultures and among different peoples. I certainly believe that the joy of preparing a meal and sharing it with people is incredibly powerful, and incredibly therapeutic. As my daughter likes to say, one seasoning every cook should use is the pleasure of a hearty gathering, which should be sprinkled generously on every plate. Who needs a handful of digestive supplements when you have good, real food and good, real company?

Yet, like all things, meals can have either positive or negative emotional “seasonings,” both of which affect the way our body digests food. Our gastrointestinal tract (GI tract) is very sensitive to our emotions, since it is connected to the brain’s hypothalamus, which controls both the feelings of satiety and hunger, and deals with our emotional state of mind. The mind and the gut are acutely interconnected, and thus happiness, joy, and pleasure, as well as anger, anxiety, sadness, and bitterness, for example, trigger a physical reaction in you digestive system. The large and small intestines are densely lined with neurons, neuropeptides and receptors (the “doorways” into cells), which are all rapidly exchanging information laden with emotional content. Indeed, we have all experienced this gurgling emotional activity in our guts, colloquially known as a being “sick to your stomach,” a “gut-feeling” or having “butterflies in your stomach.”

Unless we are aware of what our digestive system is telling us, we may fall into the trap of overeating. The pancreas releases at least 20 different emotionally-laden peptides, which regulate the assimilation and storage of nutrients, and carry information about satiety and hunger. Do not ignore the information these peptides provide. Just as eating when you are angry or trying to bury another unpleasant emotion will affect the way that the nutrients in your food are assimilated, eating when you are not hungry will upset your digestive system. Overeating will make the food you eat or drink less beneficial, since the emotions generated by toxic thinking interfere with the proper workings of your body. Eating when you are in a distressed emotional state, or not hungry, is essentially like adding every spice and herb in your cupboard to your meal. All these seasonings will destroy the balance of flavors among the meal’s components. Emotionally-driven food consumption literally adds a flood of chemical, emotional “seasonings” to your food: your digestive system, like your palate, will not know how to interpret such a conflicting range of signals.

When we react incorrectly to the events and circumstances of life, we actually move into toxic stress, or stages two and three of stress. Toxic stress keeps your “fight or flight” response activated, which inhibits gastrointestinal secretion and reduces blood flow to the gut, thereby decreasing metabolism and affecting your body’s ability to digest food. In fact, toxic thinking and emotions, which lead to toxic stress, can affect the movement and contractions of the GI tract, cause inflammation, make you more susceptible to infection, decrease nutrient absorption and enzymatic output, upset the regenerative capacity of gastrointestinal mucosa and mucosal blood flow, irritate intestinal microflora, cause your esophagus to go into spasms, give you indigestion and heartburn by increasing the acid in your stomach, make you feel nauseous, cause existing digestive issues such as stomach ulcers to worsen, and agitate your colon in a way that gives you diarrhea, constipation and/or extreme bloating. To say that you should not eat food when you are stressed, unhappy, angry or any other negative emotion is most certainly an understatement.


Yet thinking good thoughts cannot excuse an unhealthy diet. The digestive system itself is a rich source of neurotransmitters, which carry signals inside the brain and body. In fact, 95% of the serotonin and half the dopamine in the body are produced in the gut. Considering these neurotransmitters are famous for their mood-calming and reward effects respectively, we should be paying a lot more attention to what we are putting in our gut—what you eat affects the way these neurotransmitters function. Indeed, beneficial symbiotic gut bacteria produce benzodiazepine-like substances, which are naturally occurring anti-anxiety neurochemicals. A healthy gut promotes a calm, satisfied and happy mind.

For more on the history and research of the gut-brain connection, get the book, “Think and Eat Yourself Smart,” or the “63-days to Think and Eat Yourself Smart” online program.
By: Dr. Caroline Leaf