What is IBS?
Causes, Diagnosis, Triggers, Treatments & Coping  

What is IBS? 

Irritable Bowel Syndrome:
Causes, Diagnosis, Triggers, Treatments & Coping 

By Trish Whetstone
Instagram: @feelgoodgutgirl 

Many of us are not strangers to digestive upset — including bloating after a large meal, indigestion upon eating fried foods, or the occasional bout of bathroom trips after indulging in particularly spicy food. So it's no surprise that digestive aids such as acid reducers often lead over-the-counter drug sales in the United States. But the question stands - what is Irritable Bowel Syndrome (IBS) anyway? It is one of the most common disorders of the gastrointestinal (GI) tract afffecting at least 10%-15% of the world's population.1

What is Irritable Bowel Syndrome?

As the name denotes, IBS is considered a syndrome, which differs from an Irritable Bowel Disease such as Chrohn's or Ulcerative Colitis. A disease can be distinguished from other conditions because of its particular collection of signs and symptoms, and unique pattern of onset, process, and treatment.2 

A syndrome is also categorized by a particular set of signs and symptoms. Still, the variance among those with this condition is more significant, as one person may have a different collection of symptoms than another person. Additionally, the exact etiology or cause of syndromes are less understood, and treatment and management options vary significantly in effectiveness from person to person.2

IBS can generally be defined as the recurrence of abnormal bowel patterns, abdominal pain, gas, and/or bloating.

Furthermore, IBS cases are categorized into four sub-types: 

  • IBS-D in which diarrhea is the primary concern 
  • IBS-C in which constipation is the primary concern 
  • IBS-M "mixed" in which an individual experiences a mix of bowel movements ranging from diarrhea to constipation, potentially even within a single day
  • IBS-U "unclassified" in which an individual may experience a combination of bowel patterns, or the primary concern is bloating, gas, and abdominal pain3

Causes of IBS

The cause of IBS is continually under examination. Still, experts agree that IBS development is not from a single cause but a collection of biopsychosocial internal factors and external factors. These include:

  • Infection
  • Antibiotics
  • Bacterial Overgrowth
  • Psychological Factors
  • Lifestyle Factors 


In about 10% of IBS cases, the syndrome appears after bouts of diarrhea due to food poisoning or a "stomach bug."4

This is due to the introduction of specific invaders that influence the delicate balance of the gut microbiome. 

The gut microbiome is a collection of microbes, including bacteria, viruses, and fungi, that live in balance within the ecosystem of the colon (the gut).

"Bad" microbes may affect the function of the "good" microbes that live in harmony within the body and contribute significantly to effective digestion and immune function. More on this soon!


Antibiotics work by killing off bacteria and are thus used to combat bacterial infections. The caveat is that antibiotics typically kill off the entire colony of bacteria within the gut, even when the condition is not localized within the gut, such as with a case of strep throat.5

Therefore, even the helpful bacteria within the colon need to recolonize after antibiotic use.

A tremendous body of research points to antibiotic use and microbiome disruption as a causal factor in IBS development. In one study, subjects given antibiotics were more than three times more likely to report persistent bowel symptoms even four months later than a control group.6

Bacterial Overgrowth

Gut dysbiosis is defined as a reduction of microbial diversity, the loss of beneficial bacteria, and the increase of potentially pathogenic (harmful) bacteria within the gut.7

Subsequently, the disruption of bacterial homeostasis (balance) with the gut plays a role in developing IBS. A huge one. It is estimated that upwards of 78% of IBS cases result from Small Intestinal Bacterial Overgrowth (SIBO).8

SIBO develops when certain bacteria customarily found within the large intestine migrate to and grow within the small intestine. Many of the symptoms associated with SIBO mirror IBS, so SIBO may be an underlying cause of these GI disruptions.8

Psychological Factors

Those who suffer from IBS often recognize that stress and mental or emotional strain contribute to "flare-ups" or increased IBS symptoms. These issues can involve the Gut-Brain Axis and the Autonomic Nervous System.

The gut and the brain are connected via the vagus nerve. This connection is responsible for the bidirectional transmission of neurotransmitters and hormones between the gut and the brain. Rodent studies show that emotions and mental stress transmit signals through the vagus nerve and thus play a role in stomach aches and pains.

Additionally, IBS sufferers have been shown to have decreased vagus nerve tone and function, which may play a protective role in digestive health. Stress hormones like cortisol can also negatively influence the gut flora and contribute to dysbiosis.9

The Autonomic Nervous System has a direct impact on digestion as well, with the activation of two opposing responses: 

Sympathetic Nervous System

Parasympathetic Nervous System 

  • The Stress Response 
  • Fight, Flight or Freeze
  • Breathing becomes shallow 
  • Blood rushes away from gut to appendages (to mobilize the body for action) 
  • Digestion shuts down
  • The Relaxation Response
  • Rest & Digest 
  • Breathing returns to normal 
  • Digestion is optimized 
  • Healing processes 

Persistent activation of the Sympathetic Nervous System shuts down the digestive process, and causes disruptions in motility. Motility refers to the movement of food throughout the entire digestive tract.10

Disruptions in motility can cause irregularities in bowel movements (such as increased constipation and diarrhea) as well as gas, bloating and abdominal pain. 

Lifestyle Factors

It's no surprise that diet plays a role in the onset of IBS. Poor nutrition is linked to gut dysbiosis and the promotion of an inflammatory environment within the gut. A lifelong diet of highly processed food promotes less biodiversity within the gut than a whole foods diet. Other lifestyle habits contributing to IBS include physical inactivity, sleep disturbances, irregular eating patterns, or poor meal timing.11

Diagnosing IBS

Approaches to diagnosing vary by practitioners, as there is no one specific diagnostic test for IBS yet. Some may suggest diet and lifestyle change first, saving more extensive testing for symptoms. At the same time, other practitioners may begin by ruling out other gastrointestinal disorders. 

The Bristol Stool Chart is a tool used to measure the time food travels throughout the digestive tract before leaving the body as waste. It also shows the size and shape of stools associated with constipation and diarrhea, which can help identify the type of IBS.12

  • Stool types 1 and 2 denote constipation
  • Stool types 5, 6, & 7 denote diarrhea
  • Stool types 3 and 4 show optimal bowel movements

It is essential to seek medical testing if you experience any of the following alongside typical IBS symptoms13

  • Concerning weight loss
  • Blood in stool or rectum
  • Fever
  • Recurrent vomiting or nausea
  • Excessive abdominal pain
  • Persistent diarrhea, especially in the middle of the night
  • Anemia or low iron

These signs may be an indication of another serious medical condition. Potential tests to identify other conditions and rule out IBS include:

Diagnostic Procedures

-> To detect Irritable Bowel Diseases such as Chrohn's or Ulcerative Colitis, or polyps on the intestines 

-> This testing may consist of a Colonoscopy, X-Ray, CT Scan, or upper endoscopy 

Laboratory Tests

Breath tests can detect:

-> Lactose intolerance, a condition in which the body cannot digest lactose, the sugar in dairy products
-> Bacterial overgrowth in the small intestine (SIBO)

Blood work can test for autoimmune conditions such as Celiac Disease (a condition in which the body's immune cells attack the intestines upon ingestion of gluten) and Thyroid diseases, which can contribute to GI disruptions

Stool testing:

examines bacterial or parasitic infections or conditions of the liver13

Often an individual may receive an IBS diagnosis based on their symptoms of general GI upset. Upon further testing, they may find that SIBO, lactose intolerance, Celiacs, or other conditions were present. However, it is essential to note that comorbidity is common with digestive disorders, meaning an individual may be diagnosed with IBS and SIBO, or IBS and lactose intolerance.

Everything considered, IBS is the general label given to ongoing GI disruptions, whether or not another condition is present. If an underlying condition is addressed and properly managed, an individual will likely no longer receive an IBS diagnosis.

In some perspectives, IBS is seen as a chronic condition or essentially something an individual will have to deal with throughout life. However, other schools of thought argue that properly healing gut disruptions can alleviate IBS entirely. So let's dive deeper into the ways IBS is treated and managed to learn more.

Managing and Treating IBS

Much like the diagnosis of this syndrome — the management and treatment of IBS differs across disciplines. Most experts agree there is no "cure" for IBS, and treatment focuses on managing and preventing symptoms so the individual can live as comfortably as possible. However, other experts argue that successfully treating an underlying condition like SIBO results in total remission of IBS symptoms.

Most conditions of the GI tract, including Celiacs, SIBO, and lactose intolerance, require lifestyle modifications. Seeking help from the following professionals may be part of an individual's treatment plan: Registered Dietician, Functional Medicine Practitioner, Certified Nutritionist, Naturopath, Certified Health or Life Coach, Certified Therapist or Counselor.

Avoiding Triggers

One way to successfully manage IBS is to avoid triggers that cause a "flare-up" or onset of symptoms. Triggers vary significantly among individuals based on their biology and lifestyle. 

Finding Food Triggers Through Elimination Diets

Food triggers differ for each individual and can be identified most accurately through an elimination diet. This is a period of a few weeks or months in which an individual will restrict certain foods, take note of any improvement of symptoms, and then reintroduce these foods back into the diet, detecting any persistent reactions.

Current research shows that elimination diets are a better option than allergy or food sensitivity tests which may yield inaccurate results at this time.1

Some common elimination diets may include the restriction of:

  • FODMAPs, are short-chain carbohydrates not fully digested or absorbed by the intestines. This acronym stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols —components found in primarily various carb and sugar-based foods including wheat, lactose, legumes, and certain fruits and vegetables. A low FODMAP diet has been shown to reduce IBS symptoms in up to 75% of individuals who follow this plan.14 
  • Dairy and gluten are two of the most common individual food triggers, even in those who do not have a milk allergy or Celiac disease. Temporary elimination and reintroduction of different gluten and dairy foods can also help determine an individual's tolerance for these foods. 
  • High-gas and high sugar foods and drinks like carbonated beverages, alcohol, processed foods, and fried foods are also common triggers of IBS. 
  • Caffeine is a stimulant drug and diuretic, which can aggravate bowel patterns and promote diarrhea. 

It is important to note that food sensitivities or intolerances are distinct from allergies. The food needs to be avoided entirely. Depending on the severity of symptoms, an individual with a food sensitivity may or may not need to restrict certain foods altogether. In many cases, a person will need to be mindful of the portions of the foods they consume. In other words, food sensitivities or intolerances (which often cause GI reactions to foods) exist on a spectrum. For example, some people who are lactose intolerant have symptoms from any dairy product in any quantity. Others find they can tolerate certain low lactose cheeses to a certain degree before experiencing any symptoms. 

Finding Lifestyle Triggers

Along with diet, other lifestyle factors can cause IBS flares, including13

  • Periods of high stress
  • Lack of sleep
  • The menstrual period in women (potentially due to hormonal changes) 
  • Physical inactivity
  • Inadequate hydration

Promoting a healthy gut 

While actively avoiding triggers, it is also vital for IBS sufferers to regularly practice nutrition and lifestyle habits that nourish the digestive system. 

Prioritizing Balanced Nutrition

A diet consisting of primarily minimally processed whole foods high in fiber and containing prebiotics can help promote healthy bacteria within the gut. In addition, probiotic-rich foods such as fermented foods can help enrich the gut microbiome.

The addition of anti-inflammatory foods such as olive oil, nuts, seeds, and a variety of fresh or frozen produce can have additional benefits. Colorful plant-based foods contain polyphenols and phytochemicals that soothe inflammation within the gut lining. Green teas and herbal teas like ginger, peppermint, fennel, and turmeric soothe an upset stomach and help alleviate bloating and gas.

Prebiotic Foods

Probiotic Foods

Anti-Inflammatory Foods

  • Apples
  • Bananas
  • Chicory Root
  • Garlic 
  • Onions
  • Asparagus
  • Oats
  • Lentils 
  • Artichokes
  • Yogurt
  • Kefir
  • Pickled Foods
  • Fermented Foods
  • Miso
  • Kombucha
  • Sauerkraut
  • Tempeh
  • Soft Cheeses
  • Sourdough Bread
  • Berries
  • Leafy Greens 
  • Teas
  • Spices such as cinnamon & turmeric 
  • Sweet Potatoes
  • Dark Chocolate
  • Avocados

Ultimately nutrition for a healthy gut in IBS sufferers will be individual. It is helpful to work with a trusted support or accountability coach to work through periods of trial and error until finding the optimal way of eating that yields the best results. Some whole foods can aggravate an inflamed gut, so slowly reintroducing a greater variety of foods over time is recommended.

Some prebiotic and probiotic foods may cause gas and bloating in IBS sufferers and may need to be limited while following specific diets, such as the low-FODMAP diet. Therefore, supplementing with well-researched nutrition products, such as prebiotic supplements, can be hugely beneficial (more on this soon!).

Prioritizing Stress Management and Prevention

Habits that prioritize restful sleep, regular exercise, and mindfulness all contribute to lower stress levels and normal gut motility, resulting in fewer incidences of IBS flare-ups.

Sleep, exercise, and proper hydration also help to manage hormonal levels of glucose and insulin (responsible for blood sugar), ghrelin and leptin (responsible for hunger and fullness), and cortisol and melatonin (responsible for restful sleep and proper healing). In addition, hormonal regulation impacts digestive acids, muscle contractions within the intestines, and gut flora.

Additional recommendations for managing IBS symptoms from a mental wellness lens include hypnotherapy and cognitive behavioral therapy.1

Medications and Supplements for IBS

Certain over-the-counter and prescription medications have shown effectiveness in the management of IBS symptoms. Individuals may seek guidance from their healthcare provider to find the proper medication for them, based on their IBS type (constipation vs. diarrhea-predominant). These medications work by either increasing fluid within the intestines or slowing down the motion within the GI tract. Pain medications may also be prescribed to ease severe cramping and painful bloating.1

Other individuals may opt to manage symptoms with supplementation. Research and recommendations on medication and supplementation vary greatly. Hence, it is essential to work alongside a practitioner when choosing suitable treatment options.11

Medications -> Antispasmodics are a class of drugs commonly prescribed that prevent muscle spasms within the intestines and subsequent pain and cramping. Interestingly, some of the highest quality evidence points towards the use of low-dose antidepressants to improve IBS symptoms, even over other medications directly combating constipation or diarrhea, such as long-term prescription-strength laxatives. SSRIs are another class of antidepressants showing some promise in managing IBS, further strengthening the case for mental health management, alongside digestive regulation.1

Supplements -> Supplementation shows promise in managing IBS symptoms and promoting a healthy gut lining and microbial ecosystem.15

Therefore, supplementation may aid in the healing of some of the underlying causes of IBS.

Some of the most promising supplementation options for IBS are detailed below:

Supplement Type

How it works

Fiber Supplements such as Psyllium

Add fluid & bulk to the stool to promote bowel movements with greater ease

Feed the “good” bacteria within the gutPromote the growth of beneficial probioticsHelp ward off infections and inflammation

Improve the diversity & colonization of beneficial bacteria within the gut microbiome

Digestive Enzymes such as Lactase enzymes

Aid in the digestion & breakdown of certain macronutrientsEx: Lactase breaks down the sugar lactose found in dairy products

Essential Oils such as Peppermint oil

Relieve nausea and pain associated with cramping, gas & bloating


IBS is a unique syndrome, so diagnosis and care should be individualized. Holistic approaches that consider nutritional, lifestyle, and supplemental interventions yield the most significant long-term success.

Although common, digestive and gut concerns do not need to be accepted as "normal." An unhealthy gut is not normal, and a healthy, properly functioning gut is possible! So be curious, listen to your body, and seek support. Here's to feeling good in your gut!


1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6507291/

2. https://healthcare.utah.edu/the-scope/shows.php?shows=0_398izmir

3. https://cara.care/digestive-disorders/ibs/ibs-diagnosis/

4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5283907/

5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120961/

6. https://pubmed.ncbi.nlm.nih.gov/11808932/

7. https://www.sciencedirect.com/science/article/pii/B9780323430449000194?via%3Dihub

8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5347643/

9. https://www.frontiersin.org/articles/10.3389/fnins.2018.00049/full

10. https://health.ucsd.edu/specialties/gastro/areas-expertise/motility-physiology/pages/default.aspx

11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4562783/

12. https://www.webmd.com/digestive-disorders/poop-chart-bristol-stool-scale

13. https://www.mayoclinic.org/diseases-conditions/irritable-bowel-syndrome/symptoms-causes/syc-20360016

14. https://www.monashfodmap.com/about-fodmap-and-ibs/

15. https://layerorigin.com/pages/what-is-hmo-2

Written by: Trish Whetstone — Certified Health, Life, Nutrition & Wellness Coach

Trish is a certified gut health coach for busy professionals with digestive concerns. She helps her clients manage stress, emotional eating & food sensitivities, by simplifying nutrition & lifestyle habits.

Trish received degrees in Psychology & Public Health from The State University of New York at Fredonia and worked in the non-profit sector as an Educator, Coordinator & Director.

After waking up too many times in her early twenties feeling like she got hit by a bus, Trish said "enough is enough". She healed her gut after years of struggling with IBS (irritable bowel syndrome) and became a Certified Health, Life, and Nutrition Coach to help others do the same.

Through her personal coaching business, Health Coaching by Trish, she helps busy professionals with nutrition, stress management, and lifestyle change, so they can feel good in their gut!

Website: www.healthcoachingbytrish.com

Contact: trishmwhetstone@gmail.com

Instagram: @feelgoodgutgirl

Facebook: Health Coaching by Trish 

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