Phases of Digestion – Part 1 of the 5

Without exaggeration, improving my patient’s digestion is one of the cornerstones of helping them regain or maintain their health. As a biological system, digestion interacts with every aspect of human physiology, and without proper digestive function, no system in the body operates optimally. Throughout this five-part series, we will explore DIGESTION—moving systematically from beginning to end, literally. Each part will delve into essential organs and functions: the stomach, small intestine, liver, gallbladder, and colon. However, we cannot jump into anatomy and mechanics without first addressing the most critical influence on digestion—our mental state. This initial part explores the profound link between stress and digestion, unraveling how our thoughts, feelings, and reactions profoundly affect how we break down and absorb nutrients.

The most crucial component affecting digestion occurs long before food hits our lips. This may sound surprising, but digestion does not simply start in the mouth; it begins in the brain, with our mental and emotional state. Before, during, and after meals, our state of mind directly influences the effectiveness of digestion. A tense or distracted mental state—feeling stressed, anxious, or hurried—throws our digestive system into disarray. It suppresses enzymatic activity, decreases nutrient absorption, and slows motility, creating a cascading chain of disruptions in how the body processes food. Think of digestion as a relay race: if the brain signals chaos, the handoff to subsequent organs (like the stomach, intestines, and liver) happens with fumbled precision, compromising everything down the line.

We often ignore that digestion is an integrated partnership between two components of our nervous system: the sympathetic nervous system (FIGHT-FLIGHT mode) and the parasympathetic nervous system (REST-DIGEST mode). Let’s explore these more deeply.

Stress Affects Digestion – The Parasympathetic and Sympathetic Nervous Systems

Sympathetic Nervous System

The sympathetic nervous system, often called the “fight-or-flight” system, prepares the body to face perceived threats. In times of stress—like narrowly escaping an accident, tackling a tight deadline, or coping with anger—this system kicks into high gear, prioritizing resources for immediate survival. Blood flow is diverted from organs that aren’t needed in these scenarios (like the gut) and directed to the muscles, heart, and lungs to help you “escape.” Stress hormones like epinephrine (adrenaline) and cortisol are released, accelerating the heart rate, tensing the muscles, and temporarily shutting down digestive functions. Under these conditions, every primary digestive function is suppressed:

  • Saliva and digestive enzymes decrease, impairing the initial breakdown of food in the mouth and stomach.
  • Stomach acid production slows, affecting protein digestion and causing bloating, heartburn, nutrient malabsorption, and possibly SIBO.
  • Bile secretion and intestinal motility are reduced, which leads to the sluggish movement of food through the GI tract and contributes to constipation or bloating.
  • Blood flow to the digestive organs decreases, limiting their ability to extract and absorb nutrients.
  • The gut immune system becomes compromised, weakening defenses against pathogens and inflammation.

For many individuals, the consequences of eating while in a fight-or-flight mode can manifest as gastritis, constipation, diarrhea, acid reflux, food intolerances, and even immune-related food sensitivities. Chronic stress affects digestion, wearing down the protective mucus barrier of the stomach, increasing susceptibility to ulcers and irritation of the intestinal lining. This is how, on a physiological level, stress affects digestion and ultimately harms overall health.

To better illustrate, let’s examine common scenarios where we eat under sympathetic dominance:

  • Eating while driving, especially in traffic, amplifies physical tension and mental distraction. Adding a phone call or heated discussion further heightens stress, virtually shutting digestion off.
  • Rushing while eating—whether scarfing food at your desk or cramming a meal in 10 minutes—prevents proper mastication (chewing), leading to inefficient digestion later.
  • Standing or multitasking while eating splits focus, robbing the digestive system of needed calm and resources.
  • Even activities perceived as relaxing, like watching an intense television show, stimulate stress responses through heightened arousal, impacting digestion.

Parasympathetic Nervous System

Thankfully, the body comes equipped with a biological antidote: the parasympathetic nervous system or REST-DIGEST mode. Unlike its “fight-or-flight” counterpart, the parasympathetic system activates during calm, safe conditions. When engaged, this part of the nervous system allows:

  • Blood flow concentrates around the stomach, intestines, and liver, providing the energy needed for thorough food processing.
  • Increased secretion of saliva, gastric acid, bile, and digestive enzymes ensures that carbohydrates, proteins, and fats are adequately broken down and nutrients are absorbed.
  • Smooth muscle contraction in the intestines moves food efficiently through the GI tract.
  • Immune and microbial function in the gut to flourish, helping maintain intestinal health and balance.

Imagine your body as a carefully orchestrated symphony, where each digestive organ plays its part in perfect timing. For this symphony to work, we must grant it the calm and focus provided by rest and mindfulness during meals.

mindfulness-and-stress-free-eating-benefits-the-rest-and-digest-nervous-system

To activate the rest-digest state, mindfulness practices offer simple yet profound strategies. Consider the following guidelines:

  • Eat in a soothing environment—free from loud noises, flashing screens, or hurried distractions. Whether dining at home or elsewhere, carve out a calm and quiet space to sit and enjoy your meal.
  • Show gratitude before you eat. Expressing thanks, either silently or aloud, cultivates presence and signals the brain to enter a parasympathetic state. Reflect on how this food will nourish each cell in your body.
  • Chew slowly and thoroughly. Chewing prepares food mechanically and signals the production of saliva and digestive enzymes, laying the groundwork for the stomach and intestines to do their job effectively.
  • Focus on taste and experience. Engage your senses—notice flavors, textures, and aromas. Avoid mindless consumption. Mindfulness eating enhances satisfaction and triggers appropriate satiety signals.
  • Rest after eating to allow the body to redirect energy toward digestion. Even 10–20 minutes of gentle stillness can significantly improve absorption and assimilation.
  • Avoid eating immediately before or after workouts, as the body diverts energy toward muscle recovery during exercise, undermining digestion. Similarly, exercising right after a meal impedes digestive blood flow and may cause discomfort or bloating.

To summarize, stress affects digestion! Effectual digestion is not difficult to achieve but requires intentional effort. When we consistently provide the body with the calm, focused conditions it needs to function in parasympathetic mode, we set the stage for vibrant health, longevity, and abundant energy. Many gastrointestinal issues resolve naturally when the system is given time, space, and attention to heal. Remember, eating in calm mindfulness isn’t just about digestion—it’s a conscious investment in long-term well-being. By taking the time to eat correctly now, we allow our bodies to thrive for years to come.