IBS and Diverticular Disease: Symptoms, Differences and Fibre Guidance

Irritable bowel syndrome (IBS) and diverticular disease are two common gut conditions in Australia. Many people have both at the same time, which can make symptoms feel confusing. This guide explains each condition in simple language and helps you understand how they overlap.

What is IBS?

IBS is a functional gut condition. This means the gut looks normal on scans, but the way it moves and responds is more sensitive. IBS can cause bloating, cramping, constipation, diarrhoea or a mix of both. Stress, hormones, certain foods and gut sensitivity can all play a role.

Common IBS symptoms:

• bloating

• cramping

• constipation

• diarrhoea

• urgency

• gas

• gut pain that improves after a bowel movement

What is Diverticular Disease?

Diverticulosis and diverticulitis both fall  under the umbrella terms of diverticular disease. Diverticular disease happens when small pockets form in the wall of the bowel, this is called diverticulosis. Many people never notice them. Symptoms usually appear when the pockets become irritated or inflamed, which is called diverticulitis.

Diverticulitis is the more serious form, where the pockets become infected. This is often very painful and needs medical care.

Common diverticular disease symptoms:

• lower left abdominal pain

• changes in bowel habits

• bloating

• tenderness in the lower tummy

• flare‑ups that feel sharp or achy

How IBS and Diverticular Disease Are Different

IBS affects gut function and diverticular disease affects the gut structure.

IBS causes sensitivity and changes in gut movement, where as diverticular disease causes pockets that can become irritated or inflamed.

IBS symptoms often come and go and diverticular symptoms often flare in one area of the bowel.

Can IBS and Diverticular Disease Co‑Exist?

Many people have both IBS and diverticular disease. IBS can make the bowel more sensitive, which can make diverticular symptoms feel stronger. Diverticular disease can change bowel habits, which can trigger IBS symptoms. This overlap is common in people who have had gut symptoms for many years.

The Low FODMAP Diet Is Not Forever

The low FODMAP diet can help IBS symptoms but it is not meant to be long term. The low FODMAP diet is a short, structured phase of eating used to identify triggers. Most people can return to a more flexible, higher fibre diet once they know what works for them.

High Fibre and low FODMAP Options When You Are Not in a Diverticulitis Flare

Once diverticulitis symptoms settle, you can slowly increase fibre and then aim for steady fibre intake.

Great options include:

• oats

• chia seeds

• psyllium (if tolerated)

• wholegrain bread

• brown rice

• quinoa

• lentils and chickpeas in small amounts

• cooked veggies

• fruit with skin if tolerated

  
  

These foods support bowel health and may help prevent diverticular flare‑ups.

When to See a Dietitian

Our dietitians can help you:

• understand IBS triggers

• manage diverticular flare‑ups

• Support reintroduction of fibre after a diverticulitis flare

• build a high fibre diet that suits your gut

• use the low FODMAP diet temporarily and safely

• reduce bloating and constipation

• support long‑term gut health

• Clarify what a high fibre diet looks like for you, without including your high FODMAP triggers

At Sage Dietitians, we are based in Chelsea Heights, Melbourne and we support people across all of Australia through online and telehealth consults. 

You can book an appointment here or get in touch here to schedule a free discovery call if you’re unsure about how we can help.