Diverticular disease: how fibre can support gut health

Diverticular disease is not a topic that commonly comes up around the dinner table, yet gut health has a major influence on overall wellbeing. It is also one of the most widespread conditions affecting the large intestine.

Diverticular disease, also called diverticulosis, occurs when small protrusions or pockets, known as diverticula, develop in the wall of the colon. This often happens because the muscle layer has weakened.

Although these pockets are generally harmless, they can sometimes become infected or inflamed. This is known as diverticulitis, a condition with a slightly different name.

Diverticular disease: prevalence and symptoms

By the age of 80, roughly 70% of people in Western countries will have developed diverticular disease.

It is also becoming more common among younger adults, potentially because many modern diets are low in fibre and high in processed foods. UK dietary surveys indicate that people currently eat only 60% of their recommended daily fibre intake.

It is not fully clear why some people develop diverticular disease while others do not. However, recognised contributing factors include the colon’s structure and movement, diet, fibre consumption, obesity, physical activity and genetics.

Most people with diverticular disease have no symptoms. Some, however, may experience pain or discomfort in the lower-left area of the abdomen, often more noticeable after eating, alongside bloating, diarrhoea or constipation.

Because these symptoms can resemble those of other digestive conditions, including irritable bowel syndrome (IBS), reaching a diagnosis can be more difficult.

Despite its prevalence, diverticular disease is frequently misunderstood. While many people remain symptom-free, others have persistent digestive discomfort.

Diverticulitis, which develops when diverticula in the colon are infected or inflamed, generally causes more serious symptoms. These include ongoing abdominal pain, a high temperature, nausea and, in some instances, altered bowel habits. Urgent medical attention is needed, as untreated diverticulitis may result in complications.

Fibre and diet advice for diverticular disease

Fortunately, modest dietary and lifestyle adjustments can have a substantial effect, while old advice is rapidly being replaced by recommendations based on evidence.

In the past, people with diverticular disease were advised to avoid nuts, seeds and popcorn because of concerns that these foods could become trapped in diverticula and trigger inflammation. That belief has now been disproved.

Current guidance from the National Institute for Health and Care Excellence states that there is no reason to avoid these foods unless a healthcare professional has specifically advised it.

A high-fibre diet can, however, be beneficial. Fibre makes stools softer and easier to pass, helping to lower pressure in the colon and prevent constipation, which is a recognised risk factor for diverticulitis.

Small, hard stools can become stuck in diverticula, raising the likelihood of inflammation or infection.

Alongside increasing fibre, drinking enough fluids and remaining physically active can support healthy digestion. Water enables fibre to work properly, while regular activity may promote normal bowel function and lower the risk of complications.

If food alone does not allow you to achieve fibre targets, a doctor or dietitian may advise fibre supplements or gentle laxatives.

Practical ways to increase fibre intake

Official UK guidance recommends that adults consume at least 30g of fibre daily. Straightforward ways to achieve this include beginning the day with a high-fibre breakfast cereal and adding fresh or dried fruit.

Choosing wholemeal or granary bread, wholewheat pasta or brown rice, and adding more lentils, chickpeas, beans and vegetables to meals may also help.

For instance, grated carrot, red lentils or kidney beans can be easily mixed into mince-based meals. Raw vegetables, such as peppers or carrots, also pair well with dips including hummus or guacamole.

It is best to raise fibre intake gradually. Increasing it too quickly may lead to bloating or wind, so allow your digestive system time to adjust.

Small, lasting changes to diet and lifestyle, such as eating more fibre, staying hydrated and keeping your body moving, can lower the risk of discomfort and complications.

With current medical guidance and a balanced nutritional approach, it is entirely possible to keep your gut content, healthy and working effectively for years ahead.

Sophie Davies, Lecturer in Nutrition & Dietetics, Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.

An earlier version of this article was published in June 2025.