Statistics reveal that an estimated 5 to 10% of the worldwide population has irritable bowel syndrome (IBS). It affects people of all ages, even children. Although irritable bowel syndrome doesn’t cause structural damage it can have an impact—ranging from mild inconvenience to severe debilitation—affecting a person’s quality of life. This is why it’s important to understand what causes irritable bowel syndrome and how you can manage it.

There are many triggers of IBS symptoms, including certain foods and aspects of one’s diet. One of the IBS management options includes diet manipulation with the assistance of a trained healthcare professional, such as a dietitian. One common diet manipulation strategy that has evidence help manage the symptoms of IBS is the low FODMAP diet.

So, what is irritable bowel syndrome and its symptoms, and how can a low FODMAP diet help? Read the article to find out more about what causes irritable bowel syndrome.

Irritable Bowel Syndrome

Irritable bowel syndrome is a disorder that affects the gastrointestinal tract. It is characterized by abdominal pain or discomfort and altered bowel habits (constipation or diarrhea, or both). Previously referred to as a functional gastrointestinal disorder, IBS is now described as a disorder of brain gut interaction, meaning that there is a disruption in communication between the brain and the gastrointestinal system.

Studies found that more women than men are prone to having IBS, and their symptoms often initially occur in early adulthood. Although this disorder is not directly associated with mortality and increased risk of gastrointestinal malignancies, IBS can result in significant disability, reduced quality of life, and impaired productivity at work.

What Causes Irritable Bowel Syndrome?

The exact cause of IBS is unknown. This disorder is associated with how the gut, brain, and nervous system function and interact, which causes changes in regular bowel movements.

Although stress doesn’t cause IBS, because of the connection between the brain and gut, stress can trigger or worsen symptoms. Other factors that can trigger IBS include routine changes, infection, medication, emotional stress, toileting behaviors, eating habits and food intolerance.

low fodmap diet for IBS
Symptoms of Irritable Bowel Syndrome

Symptoms of irritable bowel syndrome vary from one person to another. Some people manage their symptoms by altering their lifestyles and managing their diets. Additional management strategies include medication and psychological therapies, such as gut-directed hypnotherapy.

The following symptoms characterize irritable bowel syndrome:

  • Abdominal pain or cramping
  • Bloating
  • Diarrhea, constipation or both
  • Excessive flatulence (gas or wind)

Symptoms of IBS can adversely affect your life, so you should seek medical advice if you suspect that you have it.  The symptoms of IBS can mimic those of many other conditions, so it is important to seek medical advice to undergo testing to rule out other illnesses, such as diverticulitis, coeliac disease, or inflammatory bowel disease.

Categories of Irritable Bowel Syndrome

IBS is subdivided into four categories:

  1. Constipation-predominant (IBS-C) – Occurs when over 25% of bowel movements involve constipation
  2. Diarrhea predominant (IBS-D) Occurs when over 25% of bowel movements involve diarrhea
  3. Mixed subtype (IBS-M) – Occurs when over 25% of bowel movements involve both constipation and diarrhea
  4. Unclassified subtype (IBS-U) – Occurs when bowel movements cannot be accurately categorized into constipation or diarrhea (I.e. mostly ‘normal’ bowel movements)

Those with IBS with alternating symptoms should avoid self-treating to avoid exacerbating their symptoms. A healthcare professional will tailor an individual treatment regimen for people with IBS to relieve symptoms because different medications work for each category.

What Are FODMAPs?

Although some people have no adverse reaction to eating FODMAPs, some people with a highly sensitive gut experience cramping, bloating, gas, or diarrhea within the hours following consumption. What does FODMAP stand for?

FODMAP refers to fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Researchers discovered that FODMAPs are a group of short-chain carbohydrates (sugars) that are poorly absorbed in the small intestine. As a result, they cannot be digested completely, which results in progression to the large intestine, where the bacteria present ferment them, releasing gas. This can trigger excess wind, bloating and pain or discomfort. Some FODMAPs are also osmotic, meaning they pull water into the bowels, which can trigger looser stools.

Studies have shown that eating less of these carbohydrates may decrease the symptoms of irritable bowel syndrome. This is known as the low FODMAP diet.

What Is the Low FODMAP Diet?

The low FODMAP diet is a 3 -phase diet that has evidence to help up to 86% of people with IBS manage their symptoms. The diet is only designed to be implemented by a trained health professional, such as a dietitian, experienced in IBS management.

The 3 phases of the diet include:

Phase 1: Elimination Phase. This phase involves reducing intake of high FODMAP foods to identify if symptoms improve. This phase typically lasts 2-6 weeks.

Phase 2: Reintroduction Phase. If significant symptom improvement is felt following phase 1, progression to phase 2 occurs. This phase involves structured reintroduction of FODMAP subgroups through food challenges to identify which FODMAP groups are well tolerated and which groups are poorly tolerated. This phase usually takes 2-3 months.

Phase 3: Personalization/Maintenance Phase. This phase involves limiting poorly tolerated FODMAP subgroups as identified in phase 2 and reintroduction of well tolerated FODMAPs back into the diet. This phase is lifelong and is designed to maximize dietary variety whilst minimizing IBS symptoms.

  1. High FODMAP foods

Common high FODMAP foods that are limited during phase 1 include:

  • Some vegetables (e.g., cauliflower, garlic, onion, green peas, most mushrooms, asparagus)
  • Some fruits (e.g., apples, mangoes, dried fruit, peaches, pears)
  • Lactose-rich dairy products (e.g., cow’s milk, , yogurt, soft cheeses, ice cream)
  • Wheat products (e.g., bread, pasta, cereals)
  • Legumes (e.g., beans, chickpeas), silken tofu and some nuts
  • Low FODMAP foods

Low FODMAP foods that can be enjoyed on the diet include:

  • Low lactose dairy products and alternatives (e.g., lactose-free milk, lactose-free yogurt, almond milk, rice milk, and hard cheeses, such as feta and brie)
  • Vegetables (e.g., green beans, carrot, broccoli heads, cucumber, lettuce, potato, zucchini)
  • Fruits (e.g., firm bananas, rock melon, pineapple, passionfruit, kiwi, oranges, lemon, lime, and strawberries)
  • Many protein sources (e.g., eggs, firm tofu, poultry, seafood, and plain cooked meats)
  • Many nuts/seeds (e.g., peanuts, pumpkin seeds, walnuts, almonds)

We recommend using the FODMAP Friendly App (Free to download) to identify suitable low FODMAP portion sizes.

People with IBS and IBS-type symptoms who think they may benefit from a low FODMAP diet should always consult a Registered FODMAP dietitian. They will support you to follow the diet correctly and ensure you are not at risk of nutrient deficiencies. Furthermore, they will help you to reintroduce certain foods into your regular diet so that you can determine which foods trigger your personal symptoms.

Are you a health professional or student aiming to become a dietitian, nutritionist, general practitioner, gastroenterologist, pharmacist or psychologist? Do you want to know more about IBS and the low FODMAP diet to help patients with digestive health issues?

Our first course through FODMAP Institute – IBS Management: The Low FODMAP Diet– is an online course that you can take to upskill in this area. The course is presented by global expert Gastroenterologists and Dietitians and takes approximately 10-12 hours to complete. It is self-paced and offers 12.25 CEUs.

Do you have further questions? Call us on +61398457155 or drop us an email at