The blog is written by author Dr Eirini Dimidi RD, Department of Nutritional Sciences, King’s College London, and is published by Proceedings of the Nutrition Society.

The blog post relates to a paper published in Proceedings of the Nutrition Society – Dietary management of chronic constipation: a review of evidence-based strategies and clinical guidelines.

Chronic constipation is a common condition that affects wellbeing and quality of life for millions of people worldwide. Dietary advice is often the first thing people are encouraged to try, yet there is still confusion about what actually works.

Research over the past two decades has explored a wide range of foods, drinks and supplements for constipation. These include fruits, high mineral water, fibre, probiotics, magnesium-containing supplements. However, dietary advice in clinical guidelines has not always kept pace with this growing body of evidence.

Kiwifruit, prunes and rye bread have all been tested in clinical trials and shown to improve aspects of constipation, such as stool frequency or ease of bowel movements. Kiwifruit is particularly notable because it has been shown to be as -or even more- effective than a commonly used fibre supplement for constipation, while also being better tolerated by people who experience bloating or abdominal pain.

Several supplements have also been investigated. Psyllium fibre supplements improve constipation symptoms, while magnesium oxide supplements may help draw water into the bowel, making stools easier to pass. Certain probiotic strains have also been shown to improve symptoms, although their effects depend very much on the exact strain used. This helps explain why some probiotics may be beneficial, while others have no effect.

Despite this evidence, many dietary strategies with good supporting evidence are mentioned only briefly, or not at all, in clinical guidelines published worldwide. At the same time, some broadly recommended approaches, such as increasing overall dietary fibre intake, lack sufficient evidence from trials. Only recently, in 2025, were the first comprehensive dietary guidelines for the management of chronic constipation published, providing detailed recommendations that reflect the available research evidence.

An important finding is that constipation does not affect everyone in the same way. Some people struggle mainly with needing to strain a lot to pass a bowel movement, while others are more affected by infrequent bowel movements, abdominal discomfort or a feeling of not having completely emptied their bowels. Different dietary approaches improve different symptoms, which means a personalised and symptom-specific approach is often needed.

Diet has a meaningful role to play in managing constipation, but understanding which dietary options work, how they work, and for whom is key to making that advice useful. Ensuring that this evidence is accurately and clearly reflected in clinical guidelines is essential for translating research into effective dietary advice in practice.