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Cortisol and the gut: Stress hormones and their influence on IBS

Cortisol and the gut Stress hormones and their influence on IBS

The topic of gut health is in the spotlight right now, and rightly so due to its relationship with many aspects of health from immunity to hormones. Increased attention is now on how we can best support the health of our gastrointestinal tract. 

This article is going to delve into the relationship between cortisol and the gut; address some common queries and provide you with practical tips you can keep in your toolbox, to support optimal gut function.

  • Unveiling cortisol: definition, role and impact of dysregulation
  • The gut-brain connection
  • Stress and gut function: what is the link between stress and gut health?
  • Understanding Irritable Bowel Syndrome (IBS)
  • Hormonal influences on gut health: can IBS affect female hormones?
  • What life stages can impact gut health?
  • What are simple steps you can take to support IBS?

Unveiling cortisol

Cortisol is a hormone produced by the adrenal glands (little hat shaped endocrine glands that perch on top of the kidneys).

When an individual experiences any type of stress, whether it's physical, emotional, or psychological, the brain signals for the release of cortisol from the adrenals.

Cortisol often gets a bad reputation being known as the ‘stress hormone’. In reality, cortisol is imperative for survival, and involved in various physiological processes including:
-metabolism regulation
-immune response
-inflammation modulation
-body’s response to stress.

While cortisol is essential for survival, dysregulation of cortisol levels is where problems can have detrimental effects on health and well-being.

In this day and age, chronically elevated cortisol is a common problem for individuals. Classic symptoms include:
weight gain, digestive disturbances, feeling tired but wired, irregular cycles, difficulty conceiving, low immunity, emotional dysregulation, along with poor memory and concentration.

The gut-brain connection

The brain and the gut have bi-directional relationship with a constant stream of dialog, through what is known as the gut-brain-axis. The gut-brain axis involves communication between the central, autonomic, and enteric nervous system, linking emotional and cognitive centers of the brain with intestinal function.

The enteric nervous system is known as the ‘second brain’ and is composed of over 100 million neurons lining the gastrointestinal tract – from the oesophagus to the internal anal sphincter and is responsible for powering up the digestive tract.

Any sort of stress can result in:
-Decreased gut motility
-Reduced blood flow to the gastrointestinal tract
-Alterations in gastrointestinal secretions

Perhaps like many, you have experienced firsthand, gut-related symptoms during times where negative emotions and stress levels were running high. From ‘butterflies’ in your tummy, to constipation or even diarrhea, these sensations and symptoms demonstrate the communication between the brain and the gut. 

What is the link between stress and gut health?

- Stress can affect gut function via alterations in the gut microbiome. Both acute and chronic stressors (which could vary from road rage to intense emotional stress), can shift the gut bacteria and rapidly affect the composition of our microbiome.

Studies have shown that during intense periods of studying, stressed university students led to a decrease in the good gut bacteria, associated with health-promoting effects; thus leaving the students vulnerable to not only digestive symptoms, but also decreased immune protection (as around 70% of immune cells reside in the gut).

Our microbiome is vital in supporting a healthy digestive system

When good bacteria becomes too low, and pathogenic species become too high, the environment becomes known as dysbiotic (essentially unfavourably imbalanced), which can result in gut-related symptoms such as bloating due to overgrowth of certain bacteria.

- Stress can also increase gut permeability, also known as ‘leaky gut’.
Our gut lining is designed to be tightly packed, but stress can allow those tight junctions to break apart, allowing unwanted bacteria to penetrate into the circulation, resulting in an inflammatory response.More and more exposure to bacterial overgrowth in the gut can trigger more leakiness in the lining and result in a vicious cycle.

- Another way that stress can affect gut function is by switching on ‘fight or flight’ mode, sending digestion to the bottom of the body’s’ priority pile.
When the brain identifies a stress, whether it be an irritating work colleague or having to run from a tiger, it has the same response which is to prioritise survival function and direct blood flow to the organs needed for survival. During ‘fight or flight’ mode, the brake pedals for gut function are pushed, resulting in slowing down of the muscles in the gut, reduced digestive secretions and overall reduced digestive function. This can consequently mean the body is producing less digestive enzymes and stomach acid, needed to break down food and absorb key nutrients; resulting in unpleasant symptoms like bloating, indigestion and hard-to-pass stools.

Understanding Irritable Bowel Syndrome (IBS)

IBS is a common gastrointestinal diagnosis characterised by symptoms such as abdominal pain, bloating, and altered bowel habits that can significantly affect quality of life.
It can involve impaired gut motility, a disruption in the gut-brain-axis, a dysbiotic microbiome and visceral sensitivity. IBS presents differently in people due to varying types: IBS-C (IBS with constipation), IBS-D (IBS with diarrhea), IBS-M (IBS with both constipation and diarrhea).
While the exact cause of IBS remains unclear, various factors, including stress, diet, the microbiome, and gut-brain interactions, are believed to contribute to its development and exacerbation. 

Can IBS affect female hormones?

IBS can have an impact on female hormones via both an altered microbiome and if there is slowed transit time (aka constipation).
-Disruptions in the gut microbiome, can impact the estrobolome's* ability to metabolise oestrogen, potentially leading to levels rising. Higher levels of oestrogen can be associated with symptoms such as more painful and heavy periods, water retention and sore breasts.
-Chronic constipation will have a similar effect, whereby oestrogen has limited capacity to be eliminated (via bowel movements) and thus has the potential to be recirculated in the body, disrupting the balance of oestrogen and progesterone, and likely manifesting as ‘oestrogen dominant’ symptoms. 

*The estrobolome refers to the collection of gut bacteria that play a crucial role in maintaining oestrogen balance in the body.

Can your menstrual cycle affect IBS symptoms?

During the latter half of your cycle, post ovulation, progesterone comes into full swing and can slow down muscular contractions, including those found in the gut.
For those already experiencing constipation, this can exacerbate symptoms of slowed transit time during the last 2 weeks of a menstrual cycle. 

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What life stages can impact gut health?

High levels of progesterone during pregnancy can also slow down bowel movements and contribute to bloating and constipation. Daily movement, stress management, hydration and fibre are all key pillars to focus on to minimise effects.

During the menopause, digestive symptoms can certainly crop up. With increasing age, and lack of oestrogen, women may experience both a decline in stomach acid, bile and enzymes needed to break down and absorb foods; along with an increased need to support a healthy microbiome.
Bloating, excess flatulence and foul-smelling stools can signify a need to prioritise stomach acid production.
Eating bitter foods like rocket, watercress and chicory is a great way to support stomach acid in order to minimise symptoms. By rotating these foods, you also get to support the microbiome via diversity.

Simple steps you can take to support IBS

Figuring out the specific type of IBS is key to supporting symptoms. But for all types, management of stress, diet, eating habits and movement is key.

Stress management

This may be via exercise, meditation, spending more time in nature or time spent connecting with others.

  • Adopting a daily ritual that helps you unwind from the day such as 5 minutes of stretching, can be an invaluable tool to keep in your toolkit to help reduce IBS symptoms.
  • Don’t underestimate the power of a good nights’ sleep. Sleep deprivation can be a stressor on the body too. Sleep is important for rebooting the body overnight, as well as regulating cortisol. Keep your room cool and dark and minimise screen time 1 hour before bed.

Diet is crucial

  • If you are unaware of triggering foods, keep a food diary with a symptom tracker to help you assess what could be aggravating your stomach. Common triggers can include dairy, alcohol, and sugar.
  • Whilst fibre is most definitely important, too much can certainly be a problem for some. If you are new to fibre, go slow and ensure you are adequately hydrated.
  • For most individuals with a sensitive stomach, cooked foods are more preferrable than raw as the cooking process helps to breakdown the foods and make them more easily digestible. If you are having a flare up of symptoms, stick to well-cooked meals such as soups and stews that are much gentler on the gut.
  • Root vegetables are a great way to get fibre in and provide a source of carbohydrates too. Think of babies who are weaned onto foods – they start with whole food sources vs. processed counterparts. Instead of breads and pastas, opt for root vegetables like sweet potatoes, regular potatoes, butternut squash and parsnips. These alternatives are much more easily digestible and are going to provide lots of nutrients.
  • Avoid alcohol, high sugar foods and artificial sweeteners which can increase inflammation in the gut as well as impacting the microbiome.
  • Support the microbiome by diversifying foods that you eat. This can simply be alternating the herbs and spices you cook with on a weekly basis.


This is another pillar to focus on when experiencing digestive symptoms.
Stretching, walking and restorative types of exercise can help to stimulate sluggish bowels and help to reduce constipation and bloating.

Eating habits

Last but certainly not least, how, and when you eat can make a huge difference.
Eating mindfully and away from distractions can help reset the nervous system and get you into parasympathetic mode – the rest and digest mode.

You aren’t so much what you eat, you are in fact what you can absorb, and your absorption of nutrients depends on being in the rest and digest mode. Keep your screens away from the dining area and take a few deep breaths before you start to eat.

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Browning, K. N. & Travagli, R. A. (2014). ‘Central Nervous System Control of Gastrointestinal Motility and Secretion and Modulation of Gastrointestinal Functions’, Comprehensive Physiology, 4(4), Pp. 1339-1368.
Borghini, R. Donato, G. Alvaro, D. Et. Al. (2017). ‘New insights in IBS-like disorders: Pandora's box has been opened; a review’, Gastroenterology and Hepatology from Bed to Bench, 10(2), Pp. 78-89.
Madison, A. & Kiecolt-Glaser, J.K. (2019). ‘Stress, depression, diet, and the gut microbiota: human–bacteria interactions at the core of psychoneuroimmunology and nutrition’, Current Opinion in Behavioural Sciences, 8(28), pp. 105-100.

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Cara Shaw - Purition Ambassador

Written by Registered Women's Health Nutritional Therapist, Cara Shaw

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