Stress Series Part 1 of 3 – WORDS JESSICA SCOTT YOUNG | NUTRITIONIST
When the body is under stress, whether it be short-term acute stress (e.g. being cut off in traffic) or prolonged periods of chronic stress (e.g work stress, poor sleep, viral illness, unhealthy lifestyle habits etc), it triggers a complex physiological response that can impact various bodily systems, including digestion.
A number of things happen physiologically to the body and digestion when under stress:
- Activation of the stress response – when you encounter a stressful situation, your body’s sympathetic nervous system (aka “fight or flight” response) is activated. This is controlled by the release of stress hormones, primarily cortisol and adrenaline, from the adrenal glands, and was designed to keep us safe from real physical danger. Back in caveman days, the sympathetic nervous system was activated so we could run away from a tiger. Our modern day lives mean the body is inundated with external stressors like stressful emails, long work hours, being cut off in traffic, so the body can’t differentiate between the stress of a bad email or being chased by a tiger!
- Increased heart rate and blood pressure – stress hormones cause your heart rate and blood pressure to rise, redirecting blood flow away from non-essential functions, such as digestion, and toward vital organs and muscles. Because when you are being chased by a tiger, you don’t need to digest your scrambled eggs, you need all your energy redistributed to your limbs so you can run away to safety!
- Decreased blood flow to gastrointestinal tract – as blood is redirected to support immediate physical responses to stress, it’s diverted away from the digestive organs, including the stomach and intestines. This can lead to a slowdown in the digestive process as digestive enzymes are inhibited and stomach acid is lowered
- Changes in appetite – stress can influence your appetite in different ways. Some people may experience a loss of appetite, while others may turn to comfort or stress-eating, often opting for high-sugar and high-fat foods.
- Impaired nutrient absorption – a reduction in blood flow to the intestines can affect nutrient absorption, potentially leading to nutrient deficiencies over time. Think low iron, low B12, low zinc.
- Altered gut bacteria – stress can impact the balance of beneficial and harmful bacteria in the gut. An imbalance in the gut microbiota can contribute to digestive issues and influence overall health.
- Increased gut permeability – chronic stress can weaken the protective barrier of the gut lining, making it more permeable. This condition, often referred to as “leaky gut,” can allow undigested food particles and toxins to enter the bloodstream, potentially triggering inflammation and immune responses. When under stress, we may be more reactive to foods that we used to be able to tolerate, because of this increase in intestinal permeability
- Increased visceral hypersensitivity – as the digestive process is disrupted, it can lead to symptoms such as bloating, gas, constipation, or diarrhea, especially in individuals with conditions like irritable bowel syndrome (IBS). Stress acts as a trigger of pain sensation, heightening visceral hypersensitivity and increasing overall digestive discomfort
- Impaired vagus nerve activity – the vagus nerve is the longest nerve in the body, connecting the brain and the abdomen via the gut-brain axis. It sends signals from the digestive system and organs to the brain and vice versa. The vagus nerve is the primary component of the parasympathetic nervous system, responsible for regulating a wide range of vital physiological functions. These functions encompass mood control, immune modulation, digestion, and heart rate regulation.