What is the difference between IBD and IBS?


What is the difference between IBD and IBS?

If you’re not sure about the different between Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD), you’re not alone. Both are chronic conditions and both affect the gastrointestinal tract (GI). They even sound similar. However, they are two quite distinct conditions that have different treatment pathways. To get best symptom relief and the best health outcomes, it’s important to get an accurate diagnosis.

This article will cover:

  • What is IBS
  • How is IBS diagnosed
  • How IBS is treated
  • What is IBD
  • How is IBD diagnosed
  • How IBD is treated

What is IBS?

IBS is what we call a functional condition. This means that someone is living with a group symptoms that have no apparent cause. In IBS the body and the gut by all means look healthy with no identifiable damage, inflammation or injury. While the cause of IBS is unknown, we know several factors that appear to exacerbate symptoms including food, hormones, the gut brain axis and the sensitivity of the nerves in and around the gut.

Approx. 15% of Australians suffer with  IBS. Unpleasant symptoms affect the lower GI tract only and include bloating, abdominal pain, excessive gas and altered bowel movements (constipation or diarrhoea or alternating between the two). To fit the IBS diagnosis, these symptoms must be occurring regularly and have been happening for some time. Although IBS is not dangerous and doesn’t damage the body anyway, symptoms can be erratic, debilitating and significantly impair quality of life.

How is IBS diagnosed?

IBS is most commonly diagnosed between 25-45 years and twice as often in women than men. Although there is currently no gene linked to IBS, it does tend to cluster in families. To be diagnosed with IBS is really a two-step process:

  1. The first step is to discuss your symptoms with your doctor. They may order blood tests, including a blood test for coeliac disease, and investigate any “red flag” symptoms. Red Flag symptoms may include unexplained weight loss, symptoms starting when you are over 50 years, blood in the stool or a family history of IBD or other bowel diseases. If you have any of these symptoms, your doctor will likely refer you to a gastroenterologist for further investigations and possibly a gastroscopy or colonoscopy.
  1. If blood tests and other investigations come back clear and a reason cannot be identified for your symptoms, the next step is to compare your symptoms to the ROME IV criteria. If you fit with ROME IV criteria, then you can be officially diagnosed with IBS. You can read more about IBS diagnosis and ROME IV criteria here.

How IBS is treated?

Given that does not have one identifiable cause, there is no cure for IBS at this time. IBS treatment is focused on minimising symptoms and maximising quality of life. Over the past 20 years knowledge around IBS and how to manage it has increased significantly. At this time, approx. 75% of people with IBS are able to achieve a substantial relief of symptoms and get back to enjoying life.

In our experience as IBS specialist dietitians, the people who get best results use a combination of:

  • Diet, including identification of food triggers and individual thresholds. Despite what google says, there are no tests that can be reliably used to identify food triggers. The only way to identify a food trigger is through an elimination and reintroduction process. The low FODMAP diet is the most well-known and well researched process to do this. At Everyday Nutrition, all our dietitians are Monash FODMAP trained. In addition we are also trained in other less well known approaches for IBS including natural food chemicals, histamines and the Failsafe diet.
  • Empirical treatments. These are strategies that are directly aimed at specific symptoms. For example the addition of a fibre supplement to address constipation or diarrhoea.
  • Gut directed hypnotherapy is also well evidenced for addressing the miscommunication between the gut brain axis. In fact, research shows that it is as effective as changing your diet. This is a great option for those who are not suited to an elimination diet e.g. people with a history of an eating disorder, pregnant women or people who are unable to change their diet at this time.

What is IBD?

Unlike IBS, IBD is an autoimmune condition which causes inflammation and damage the GI tract with serious consequences. There are two main types of IBD, Crohn’s disease and Ulcerative Colitis. People with IBD tend to have a fairly prescriptive set of symptoms.

Crohn’s disease can affect any part of the GI tract with lesions occurring anywhere from mouth to anus. Symptoms can include mouth ulcers, pain, loss of appetite, fever, diarrhoea, blood in the stool or perianal fistula causing pain or leakage near the anus. Crohn’s disease commonly affects the small intestine and interferes with absorption of nutrients, resulting in weight loss and nutrient deficiencies.

Ulcerative colitis only affects the large intestine or colon. Symptoms include abdominal pain, diarrhoea with blood or puss, rectal pain, urgency, difficulty passing stool, weight loss or fatigue.

The exact cause of IBD is still not well understood. Genetics and family history appear to predispose an individual to IBD, while environmental and lifestyle factors like stress, diet smoking and alcohol, may also play a role.

Complications of IBD may include:

  • Reduced immunity
  • Increased risk of gastro-intestinal cancers
  • Skin, eye and joint inflammation
  • Damage to the bile duct
  • Blood clots
  • Severe dehydration
  • Bowel obstruction
  • Malnutrition
  • Fistula
  • Anal fissure
  • Perforated colon
  • Toxic megacolon
  • Adverse reactions to medications used to treat IBD
  • Fatigue
  • Fever

How is IBD diagnosed?

A gastroenterologist will diagnose or exclude IBD using a combination of clinical judgement and a variety lab tests including:

  • Blood tests to check for low iron, inflammatory markers or other signs of infection, bacteria or virus’s
  • Stool tests to check for blood, parasites or inflammatory markers
  • Endoscopy, colonoscopy, sigmoidoscopy, capsule endoscopy where either a camera inserted or a pill containing a camera is swallowed. This allows the doctor to see the inside or your GI tract and assess for damage.
  • Xray, CT or MRI images may be collected to identify and evaluate damage or rule out complications

How IBD is treated?

Treatment for IBD is usually a mix of diet, medication and in some cases surgery. Your doctor can discuss medical treatment and your dietitian can help you with the type of diet that is right for you and the stage of your IBD.

Medication is central to the management of IBD and may include anti inflammatories, immunosuppressants, biologic medications, antibiotics and steroids to reduce inflammation and damage. To manage symptoms, anti-diarrhoea medication and pain relief may be recommended.

Although diet is not the cause of IBD, it does play a critical role in managing it. Nutrient deficiencies such as low iron, folate, B12 and Vit D are common and need to be assessed and treated. In some cases supplements may be required.

During a “flare up” a short term low residue diet may be recommended. This is usually only a short term requirement and our dietitians can explain what the low residue diet entails and liaise with your specialist to determine when it is appropriate for you to return to normal diet.

When your IBD is in remission, most people can return to a normal diet. Unfortunately for some, despite their IBD being well managed, they still experience gastrointestinal symptoms. In this case, diets like the low FODMAP diet can be used to minimise these symptoms and improve quality of life.

More recently there has been some research into a diet for Crohn’s disease known as the Crohn’s Disease Exclusion Diet (CDED). This diet uses partial enteral nutrition and appears to help with achieving remission in people who have not responded to medications. This diet is complex and very restrictive.

Surgery may also be offered to treat IBD. In Ulcerative Colitis the colon can be removed which effectively cures the disease. In Crohn’s disease,  approximately 2/3 of people will require surgery. However, Crohn’s can reoccur in another part of the GI tract, so surgery does not cure the condition.

Inflammation No Yes
Structural change in the gut No Yes
Change in bowel habits Yes Yes
Abdominal pain, bloating Yes Yes
Prevalence 15% <1%
Surgery No Often
Fever, anaemia, Rectal bleeding, malnutrition No Yes
Complications No Yes
Physical disability No Sometimes
Impacts quality of life Sometimes Sometimes
Social inconvenience Sometimes Sometimes
Shortens life span No minimal
Diet intervention Can be of benefit Can be of benefit

Final Thoughts

IBD and IBS may sound the same, but they are two very different conditions. IBS is really a collection of gut symptoms without a clear cause. IBD, on the other hand is associated with inflammation and requires medical intervention to manage. It is important to see your doctor and a diagnosis so that you can receive appropriate treatment.

Diet does play a role in both IBD and IBS. At Everyday Nutrition our dietitians are trained and experienced in dietary intervention to help manage your condition and optimise your quality of life.



Leave a Reply

Your email address will not be published. Required fields are marked *


Meet Joanna


Joanna is a passionate advocate, communicator and educator in the fields of gut health, nutrition and wellness.