Is there a connection between post traumatic stress and digestion? In order to answer this question, let’s look at the nervous system and how it operates, the symptoms of Post Traumatic Stress Disorder (PTSD), and how digestion works. Read on to learn more, and to find out how the healing process takes place.

The Vagus Nerve and Nervous System Arousal

There are two main states of nervous system arousal: 1) parasympathetic and 2) sympathetic. Parasympathetic nervous system arousal is responsible for “rest and digest.” Sympathetic nervous system arousal is responsible for “fight or flight.”

The field of neuroscience has shown that nervous system arousal is regulated by the vagus nerve, also called the Xth cranial nerve. The vagus nerve is basically the parasympathetic nervous system. It innervates the face, heart and gut, and under stress-free conditions, it keeps us relaxed but alert. It helps our face relax when we see another friendly face. It keeps our heartbeat within a resting rate, and keeps our gut working to digest.

However, when our brain’s alarm system, the amygdala, recognizes danger, muscular tension clamps down on the vagus nerve and changes occur in the face, heart, and gut. Pupils dilate to see more movement, and ears perk up to hear even the subtlest sounds. Heartbeat increases to pump blood into our limbs for faster flight or stronger fight. Blood pumps out of our gut to bias our energy toward movement and away from digestive processes. We may even involuntarily eliminate waste or urine in an attempt to get rid of anything that will slow us down.

When we experience an event that we can neither fight nor flee from, our nervous system kicks into a dual arousal of both sympathetic and parasympathetic nervous system arousal for a freeze response. We simultaneously feel like we are going to die if we move or don’t move. This is where trauma happens. If we cannot process the movements and arousal through our nervous systems, the trauma becomes PTSD.

Post Traumatic Stress Disorder

According to the DSM, there are five major factors that indicate someone is suffering with Post Traumatic Stress Disorder: A) a stressor, B) intrusion symptoms, C) avoidance, D) negative alterations in mood and cognitions and E) alterations in arousal and reactivity.

The stressor occurs when the person was exposed to one of the following: death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence. This stressor was either through direct exposure, witnessing the event happening to someone else, or indirectly through hearing about it from a 3rd party source. It can also happen from repeated indirect exposure for first responders to trauma, such as medical and health professionals, and may be referred to as compassion fatigue.

Intrusion symptoms occur when the traumatic event is consistently re-experienced in one of the following ways: 1) recurrent, involuntary, and intrusive memories, 2) traumatic nightmares, 3) dissociation reactions such as flashbacks, 4) intense or prolonged distress after exposure to traumatic reminders, and 5) marked physiologic reactivity after exposure to trauma-related stimuli.

Avoidance involves avoiding either internal thoughts and feelings related to the traumatic event, or external stimuli that remind the person of the trauma. These can include people, places, activities, or times of year.

When examining negative alterations in mood and cognitions, two of the following seven are present in cases of PTSD: 1) the inability to recall key features of the event (not due to other factors such as head injury or substances), 2) persistent and distorted negative beliefs and expectations about oneself and the world, 3) persistent distorted blame of self or others for causing the trauma, 4) persistent trauma-related emotions such as terror, horror, anger, guilt or shame, 5) markedly diminished interest in pre-traumatic significant activities, 6) feeling alienated from others, and 7) persistent inability to experience positive emotions.

In negative alterations in arousal and reactivity, people dealing with PTSD will exhibit two of the following six symptoms: 1) irritable or aggressive behavior, 2) self-destructive or reckless behavior, 3) hypervigilance, 4) exaggerated startle response, 5) problems in concentration, and 6) sleep disturbance.

Post Traumatic Stress and Digestion

So, how do post traumatic stress and digestion link? When we have unresolved trauma from abuse of any kind, war, or natural disasters, our nervous systems stay in a chronic state of sympathetic nervous system arousal. In sympathetic nervous system arousal, we are hypervigilant and the blood stays in our limbs rather than our bellies for digestion. Our bodies emotionally and physiologically haven’t gotten the memo that we’ve survived the traumatic events, and are still responding as though they were in the trauma.

When our bodies are in post traumatic stress, they respond to anything as a threat, including food. When we eat under stress, we interrupt all the phases of digestion. There are four main phases of digestion: 1) cephalic, or head, 2) esophageal, 3) gastric, and 4) intestinal.

The cephalic phase of digestion is a preparation phase. We get our minds in a state of relaxation and readiness for our bodies to digest with saliva and enzymes. When we are hypervigilant, this phase is bypassed almost entirely. We remain in an activated, sympathetic state.

The second phase, esophageal, is affected by post traumatic stress because we are not chewing well. Our bodies are biased toward speed. We aren’t present with our food. Our throat may be tightened as part of our sympathetic arousal. This happens in trauma as a way to clamp down on any noises we may make that could give us away to the threat. Salivary and mucous productions are inhibited, making swallowing harder. This also affects the gastric phase.

The third or gastric phase is where our stomach acids break down food into a paste called chyme, making the nutrients ready for absorption. When stomach acid is too low because the body is in a chronic state of sympathetic nervous system arousal, the chyme will sit in the stomach until the pH balance is right for moving it to the small intestines. This affects transit time for digestion and causes food to sit in the stomach longer. It also interferes with the breakdown of proteins and allows for the growth of harmful bacteria.

When our smooth muscle is hypertonic (tight) or hypotonic (limp) from chronic states of sympathetic activation, it can disrupt the functioning of our pyloric and lower esophageal sphincters. These are the doorways to our stomach from the lower and upper portions, respectively. We can experience heartburn from stomach acids escaping a weakened lower esophageal sphincter and dumping syndrome from a weakened pyloric sphincter.

By the time the food enters our intestines for absorption in the fourth phase of digestion, our livers are busy trying to filter the higher levels of cortisol flowing in our systems, slowing our blood filtration and immunity. This affects our intestinal ability to absorb nutrients into our bloodstream. Because the macronutrients may not break down into small enough chains for our bodies to readily absorb, they may enter our bloodstreams and appear to be foreign invaders to our immune systems. Food sensitivities may then develop, taxing our digestive systems even more. When our guts are not eliminating properly and full of harmful bacteria, it increases mood disorders such as anxiety and depression.

There is a parallel process happening in our gut that mirrors the avoidance symptoms of PTSD. There is a “gut brain” that contains 90% of the neurotransmitters found in the head. As post traumatic stress causes avoidance of painful internal or external stimuli in our conscious lives, our guts are avoiding stimuli that look like threats in our unconscious lives.

Most health conditions can be linked to or supported by digestive function. All sorts of autoimmune disorders, such as Irritable Bowel Syndrome, Celiac disease, and thyroid conditions are affected by gut health. Mood disorders such as anxiety and depression can also be a product of an unhealthy gut microbiome.

As we discuss in the Institute for the Psychology of Eating’s approach to personal transformation, Dynamic Eating Psychology, one of the most important ways to support health is to get the gut functioning properly. In addition to probiotics and enzymes, learning to mindfully bring yourself out of sympathetic nervous system arousal and into parasympathetic is the most effective way to reverse the negative effects of post traumatic stress and improve digestion.

If you would like more information on how to work with post traumatic stress and digestion, please see our blog on Resourcing: The Antidote for PTSD.

I hope this is helpful!

Warm Regards,

The Institute for the Psychology of Eating
© Institute For The Psychology of Eating, All Rights Reserved, 2014


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About The Author
Emily Rosen

Emily Rosen is the Director of the Institute for the Psychology of Eating, where she oversees business development strategies, student affairs, marketing and public relations in addition to her role as Senior Teacher. With an extensive and varied background in nutritional science, counseling, natural foods, the culinary arts, conscious sex education, mind body practices, business management and marketing, Emily brings a unique skill-set to her role at the Institute. She has also been a long-term director and administrator for Weight Loss Camps and Programs serving teens and adults and has held the position of Executive Chef at various retreat centers. Her passion for health and transformation has provided her the opportunity to teach, counsel, manage, and be at the forefront of the new wave of professionals who are changing the way we understand the science and psychology of eating and sexuality. Emily is also co -founder of the Institute for Conscious Sexuality and Relationship.