The autonomic nervous system, which controls and influences how our internal organs function, is comprised of two parts; the sympathetic nervous system, or “fight or flight” response, which prepares our body for action in response to stress, and the parasympathetic nervous system, or “rest and digest” response, which controls homeostasis and promotes relaxation and repair. Human bodies have evolved to use the sympathetic response when we are faced with imminent danger, such as a predator chasing us, but in modern times this state occurs more often due to everyday life stress such as rushing to work, overthinking, experiencing fear or anxiety, or feeling overwhelmed or pressured. At these times our heart rate increases, lungs dilate, pupils dilate, muscles contract, saliva is reduced, secretions and peristalsis of the stomach stop, and more glucose is converted for energy. With the lack of saliva, enzymes and secretions, as well as peristalsis, it is difficult for digestion to function optimally. Conversely, the parasympathetic response increases saliva and digestive enzymes, reduces heart rate, lungs constrict, muscles relax, pupils constrict, and urinary output increases. Activating the parasympathetic nervous system prior to and during eating is crucial to the activation of the cephalic phase of digestion.
The cephalic phase is a primary stage of digestion involving the sight, smell, taste, texture, and even thought of food, which stimulates the secretion of acids and enzymes. These chemicals are necessary for the digestion and absorption of nutrients. When you imagine enjoying your favorite meal, or you smell an enticing scent, you may feel your mouth salivate or your stomach rumble. This is your body preparing itself for digestion. In order to fully engage the cephalic phase, we need to be aware of ourselves before, during, and after eating. This process relies on attention and consciousness of our senses. Eating on the run, eating in front of the television, laptop or smartphone, eating too quickly, and not taking the time to taste and enjoy the meal are all things that can hinder digestion - or promote a sympathetic nervous system response.
Not only does our level of stress alter the function of our digestive system, but also can our state of mind and emotions toward how food looks to us and how we relate with it. There are many studies conducted which support how our sensory perceptions of food, as well as our opinions or emotions toward eating it, directly affect how well it is digested, including the bio-accessibility of its energy and nutrients.
In one study test subjects were all given the same 380-calorie milkshake but half the group were advised they were consuming a 620 calorie shake, while the other half understood they were enjoying a 140 calorie shake. The hormone ghrelin (an enzyme produced by stomach lining cells that makes us feel hungry) was measured at different points throughout the experiment. The end result revealed that those who thought they were consuming more calories had a steeper decline of ghrelin, therefore felt more satiated, and those who thought they were consuming a low calorie shake had a relatively flat ghrelin response. This experiment shows that satiety is consistent with what one believes they are consuming, rather than the actual nutritional content. The milkshake experiment is just one way we can see the impact thoughts and beliefs have on the functioning of the digestive system.
Preparing the body for digestion begins at the anticipation of food. Russian scientist and Nobel Prize winner, Ivan Pavlov, proved with his studies that not only can the sight of food stimulate salivary and gastric secretions, but the anticipation of eating does as well. This means directing your thoughts and awareness toward mealtime before beginning consumption will assist in overall digestion. When it comes to the visual sensory perception of food affecting the cephalic phase, Paul Pitchford, author of Healing with Whole Foods, explains the importance of food preparation and presentation; “Awareness of presentation transforms the meal… the meal will be more appreciated and therefore eaten more consciously, which translates physically into improved assimilation”. Meals should look and taste appealing. The food should act as an invitation and create a blissful and positive experience. This is important in activating the parasympathetic nervous system, an essential part of proper digestion.
To learn more about Mindful Eating, read the many other posts within the Mindful Practice category.