In a healthy individual, stress can manifest as anxiety, irritation, panic attacks, sensitivity, pain, fatigue, anger, and impatience. When stress evolves long-term, chronic conditions evolve and can affect digestion and what nutrients that our gut absorbs. Constantly drawing on our health reserves, stress underscores and contributes to a range of modern illnesses.
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The outcome of pathological stress on an individual is determined by the:
– length, severity and type of stressor
– early life experiences
– chemical exposure, sunlight, connection to nature
Exposure to stress results in alterations of the brain-gut interactions ultimately leading to the development of a broad array of gastrointestinal symptoms such as bloating, gas, indigestion, diarrhoea and constipation and disorders including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), food intolerances, peptic ulcer and gastroesophageal reflux disease (GERD).
The major effects of stress and gut health include:
1) Alterations in gastrointestinal motility causing conditions such as small bowel bacterial overgrowth and constipation or diarrhoea. Motility is a term used to describe the contraction of the muscles that mix and propel contents in the gastrointestinal tract. This begins in the oesophagus (carries food to the stomach), stomach (mixes food with digestive enzymes and acids), small intestine (further digestion and absorbs nutrients), and colon (reabsorbs water and eliminates indigestible food residues).
2) Increase in visceral perception. Visceral hypersensitivity is currently the most widely accepted mechanism responsible for abdominal pain. There are several features which are unique to the perception of sensory stimuli arising from the gastrointestinal tract and which differ from those coming from the rest of the body.
Even though the events within the GI tract such as the composition of food, the concentration of acid, or the strength of contractions are continuously monitored by sensory nerve fibers, only a small fraction of this sensory information ever reaches consciousness. The only sensory signals felt are: the sensation of being “full” following a big meal so that we stop eating, the sensation of rectal fullness and urgency preceding a bowel movement, and the sensation of gas which will result in an attempt to expel the gas from the upper or lower GI tract. The brain has developed mechanisms, which prevent the conscious perception of all visceral information that is not essential for the individual to respond to. However, in patients with conditions such as IBS, this inhibitory mechanism appears to be compromised. In simple terms those that experience IBS may feel more symptoms in their gut than individuals without IBS.
3) Changes in gastrointestinal secretion such as acids, enzymes, bicarb and bile. These aid digestion.
4) Increase in intestinal permeability leading to “leaky gut”. Damage to the lining of the gastrointestinal tract (small and large intestine) is common in people with conditions such as food intolerances, IBS and Crohn’s disease. The lining is meant to be just porous enough to allow digested food material into the bloodstream and no more. An influx of unwanted material causes disease.
5) Negative effects on regenerative capacity of gastrointestinal mucosa and mucosal blood flow. The lining of the gut wall is often subjected to a wide variety of substances such as alcohol, caffeine, spices, medicines and environmental chemicals. These can cause inflammation in the gut.
6) Negative effects on intestinal microbiota. Good bugs provide a foundation for digestion and immunity and they help synthesize vitamins. They keep bad bugs at bay which can cause symptoms such as bloating, gas, loose bowels, fatigue and nutritional deficiency.
It seems clear as I read through studies and research on stress and gut that there is still a long way to go to understand the intricate connections between the digestive system and the brain.