Condition Overview
Irritable Bowel Syndrome (IBS)
IBS: Overview, Symptoms, Treatments Diet & More
Do you have IBS? Let’s talk about gas, bloating, stomach distension, diarrhea and constipation. If you suffer from one or more of these symptoms periodically or on a chronic basis then you may have Irritable Bowel Syndrome (IBS). Welcome to the club. You are not alone. Up to 23% of the world’s population has IBS. It’s the number one diagnosed condition by gastroenterologists.
What is Irritable Bowel Syndrome?
Irritable Bowel Syndrome affects the small intestine and the large intestine (colon) in terms of digestive muscle movement and sensitivity to food, gas, and stools. IBS is a type of condition called a “functional gut disorder”, which means the digestive organs look normal to a doctor but the nerves and muscles are not functioning properly.
What are Symptoms of IBS?
- Upper abdominal pain and discomfort (dyspepsia)
- Gas, gas pains, bloating, and stomach distension
- Sense of early fullness after eating
- Nausea
- Diarrhea, constipation or incomplete emptying of the bowels (or a mix of these)
- Generally, relief is felt after a bowel movement
- Fatigue is a common non-digestive symptom
You may suffer from one or more of these symptoms on a periodic or chronic basis. You may feel fantastic one day and then feel poorly the next. Your symptoms may change over time. Keep in mind that everyone experiences IBS differently. This makes it difficult to diagnose and hard to treat.
Symptoms such as blood in the stool, fever, and unintended weight loss are not symptoms associated with IBS and should be addressed with a physician.
How is IBS Diagnosed?
IBS is a symptom-based condition. Because symptoms of IBS are also symptoms of other gastrointestinal conditions, your physician may rule out other possible medical conditions such as Celiac disease, inflammatory bowel disease (IBD), endometriosis, cancer, food intolerances, and food allergies, to name a few. Your doctor may utilize a blood test, stool test, x-ray and colonoscopy to rule out other conditions.
The criteria for diagnosing IBS per the American College of Gastroenterology include abdominal pain or discomfort in association with altered bowel movements over the course of 3 months.
There are three types of IBS:
- IBS – D, which the predominant symptom is diarrhea
- IBS – C, which the predominant symptom is constipation
- IBS – M, which the predominant symptoms are mixed diarrhea and constipation
If you have IBS-D or IBS-M and have had gastroenteritis from food poisoning or traveler’s diarrhea in the past, this may be the cause of your IBS. A new blood test may be able to help your doctor more confidently diagnose you with IBS and rule out Celiac disease or IBD. Ask your doctor about IBS Detex from Quest Diagnostics or IBSChek from Commonwealth Diagnostics International.
What Causes IBS?
The cause of IBS is not completely understood. Possible causes include genetics, prior gastrointestinal infection or injury to the digestive track. Factors influencing IBS may include:
- Altered motility – This describes abnormal slowing down or speeding up of the muscular contractions in the digestive tract.
- Visceral hypersensitivity – When we eat, our stomach naturally distends as it fills with food and beverage. In some with IBS, stomach distension can register in the brain as pain.
- Post-infection reactivity –A bout of traveler’s diarrhea, food poisoning or the flu, can cause short-term or long-term alterations in how the digestive system functions. This is known as post-infectious IBS.
- Brain-gut communication – The brain and gut communicate via the vagus nerve and alterations in hormones, neurotransmitters and gut bacteria can disrupt the vital messages.
- Changes to gut bacteria – Our digestive tract is home to trillions of friendly bacteria. They play a big role in digestion as well as with immune, hormone and brain function.
- Bacterial overgrowth – Studies have shown that up to 78% of those with IBS could have SIBO or Small Intestinal Bacteria Overgrowth. Many of the symptoms of SIBO are the same as IBS so you may want to be tested and treated, if necessary. Read more about SIBO.
- Food allergies and sensitivities – The top food allergens that account for 90% of all food allergies include dairy, eggs, fish/shellfish, tree nuts/peanuts, wheat and soy. Examples of food sensitivities include non-celiac gluten-sensitivity, histamine intolerance, nightshade intolerance, etc.
- Carbohydrate malabsorption – Most people with IBS respond well to a Low-FODMAP Diet, which limits fermentable carbohydrates. Lactose and fructose intolerances are common.
- Abnormal serotonin regulation – Serotonin is a neurotransmitter that is commonly known as our body’s mood stabilizer. It is mostly found in the gut and has a role in digestion, sleep and mental health. Studies show that those with IBS-C have low levels of serotonin while those with IBS-D have high levels.
IBS & Other Conditions
Those with IBS may have other chronic conditions such as:
- Acid reflux or GERD
- Fibromyalgia
- Headaches
- Backaches
- Mental health disorders like anxiety and depression
What Triggers IBS Symptoms?
Food is one of the main triggers via food sensitivities, food intolerances or visceral hypersensitivity. Other triggers may include:
- Big meals
- Meals high in fat
- Caffeine
- Alcohol
- Coffee
- Stress
- Gastrointestinal infections
- Menstrual cycle – hormonal changes can affect digestive function
How Is IBS Treated?
Since IBS is not defined by one set of symptoms and triggers may differ for each person, there are a variety of treatments.
Dietary Recommendations – Food, meal size and meal frequency can affect IBS symptoms. The first stage of dietary changes often include the following recommendations:
- Regular meal times – Studies show that erratic meal times can affect motility and therefore cause symptoms. Eat three meals a day (and snack as needed) on a regular basis. Avoid skipping meals, which can lead to increased hunger and overeating.
- Avoid big meals – Large meals can lead to IBS symptoms including bloating, gas and abdominal pain.
- Limit alcohol – Alcohol is known as a gastric irritant. It can alter motility, affect nutrient absorption and potentially increase intestinal permeability (aka “leaky gut”).
- Limit caffeine – Caffeine can increase gastric acid levels and can have a laxative effect in certain people. Caffeine can be found in coffee, tea, energy drinks and dark chocolate.
- Watch for spicy foods – Spicy food may aggravate acid reflux for some people. A chemical compound in red peppers can increase motility.
- Assess fat intake – Some of those with IBS report increased symptoms with higher fat intake. Studies are not conclusive that fat can adversely affect IBS so an individual assessment may be necessary.
- Fiber – For some people with IBS, fiber can exacerbate symptoms of abdominal pain, bloating and belly distension. Studies have shown that flaxseeds can help with IBS-C. It’s not clear what the optimal level of fiber is and may require experimentation with gradually increasing fiber in the diet.
- Fluids – Your body and your digestive tract need fluid to function optimally. Water and non-caffeinated herbal teas are ideal options. Avoid carbonated beverages like beer, seltzer, and soda since they have been reported to cause IBS symptoms.
The Low-FODMAP Diet – Studies have shown that the low-FODMAP diet can improve symptoms in up to 2/3 of those with IBS. Many will see relief in about two weeks but for some, it may take up to four weeks. The low-FODMAP diet is a short-term elimination diet that limits fermentable carbohydrates. Foods are then reintroduced in a systemized manner in order to determine which carbohydrates trigger symptoms. This is a complex diet and it’s best to work with a nutritionist in order to ensure proper implementation and food challenges. Read more about the Low-FODMAP diet.
Mind-Body Therapies – Since stress often triggers IBS symptoms, cognitive behavioral therapy, hypnosis and relaxation techniques may be effective.
Exercise – Moving keeps your digestive tract moving! Studies have shown that low to moderate levels of exercise can reduce IBS symptoms, promote increased clearance of gas and improve constipation. Think brisk walking, hiking, bike riding, swimming, etc. Also, yoga has been shown to improve IBS symptoms by improving GI function and decreasing levels of stress. Keep in mind that vigorous exercise like running may worsen IBS symptoms.
Medication – Doctors may prescribe medications that help alleviate specific symptoms and/or medications that help regulate serotonin levels.
Probiotics –High quality scientific research of probiotic use for IBS found that probiotics can reduce abdominal pain and improve symptoms such as abdominal distention, bloating, flatulence, and altered bowel movements.
Our Functional Nutrition Approach to IBS
As you can see there are numerous dietary and lifestyle changes that can help improve IBS symptoms. The trick is to determine the right approach specifically for you. We work with clients to:
- Review your detailed health history to determine the potential root cause(s) and concurrent health conditions
- Help determine if you have the correct diagnosis or another condition with similar symptoms, like lactose intolerance, fructose intolerance, food sensitivities, Celiac disease, Crohn’s Disease or SIBO
- Understand symptoms and triggers
- Recommend a diet personalized to your tastes, sensitivities and lifestyle
- Address nutrient deficiencies, if necessary
- Advise on lifestyle changes and stress reduction techniques
- Reintroduce foods slowly and systematically to determine remaining food sensitivities and intolerances
- Support you every step of the way!
Call BS on IBS! Schedule Your Free Strategy Session
View References
Cozma-Petrut, A., Loghin, F., Miere, D., & Dumitrascu, D. (2017). Diet in irritable bowel syndrome: What to recommend, not what to forbid to patients! World Journal of Gastroenterology : WJG, 23(21), 3771–3783.
Didari, T., Mozaffari, S., Nikfar, S., & Abdollahi, M. (2015). Effectiveness of probiotics in irritable bowel syndrome: Updated systematic review with meta-analysis. World Journal of Gastroenterology : WJG, 21(10), 3072–3084 https://doi.org/10.3748/wjg.v21.i10.3072
Saha, L. (2014). Irritable bowel syndrome: Pathogenesis, diagnosis, treatment, and evidence-based medicine. World Journal of Gastroenterology : WJG, 20(22), 6759–6773. https://doi.org/10.3748/wjg.v20.i22.6759
University of Nebraska-Lincoln. Allergenic foods and their allergens. (2018). Retrieved from https://farrp.unl.edu/informallbig8
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Our clinical nutritionists take a functional medicine approach to digestive health so we learn the root cause of your symptoms for quick results & lasting relief.

Sara Kahn
MS, CNS, CDN

Stacy Roy
MS, BCHN, CNE
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