Constipation is common, and can happen for a number of reason - like changes in your normal routine - like travel or illness, low fluid, and fibre intake, and low physical activity can all affect bowel function.
Certain medications may also contribute, including iron supplements, some pain medications, diuretics, and medications used to manage heart conditions, allergies or mental health. If you think a medication is affecting your bowels, speak with your GP or pharmacist rather than stopping it yourself.
How do you know you’re constipated?
Constipation is not only about how often you go to the toilet, but also about the consistency. Common signs include:
- Passing hard or lumpy stools (a 1 or 2 on the Bristol Stool Chart)
- Straining to open your bowels
- Feeling as though your bowels have not emptied completely
- Feeling as though there is a blockage
- Needing to change your position on the toilet to pass a bowel motion
- Having fewer than three bowel motions per week
If you regularly experience two or more of these symptoms for at least three months, speak with your GP. They can help identify whether you have chronic constipation and check for any underlying causes
What can you try?
New evidence-based guidelines from the British Dietetic Association have identified several specific foods and supplements that may help adults with chronic constipation.
You do not need to try everything at once - choose one option that suits your symptoms and preferences, and trial it consistently. Starting several strategies together may increase bloating or diarrhoea and makes it difficult to know what has helped.
You may find it helpful to keep a written record of your bowel frequency, stool consistency, straining and any other variables like stress, activity, or food intake. If one strategy does not provide a meaningful improvement after an appropriate trial, you can consider another option or seek individual advice.
1. Kiwifruit
Try eating two to three kiwifruit each day for at least four weeks.
Research suggests that kiwifruit can improve bowel frequency and may work as well as psyllium for providing overall constipation relief. It may also cause less bloating, abdominal pain and wind, making it a good first option for people with sensitive bowels. Kiwifruit can increase the amount of water held within the bowel and add bulk to stools, helping them become softer and easier to pass.
Enjoy them on their own, or with Greek yogurt and granola, in a parfait, or on top of overnight oats.
3. Psyllium
Psyllium has the clearest evidence of the dietary strategies currently available. It absorbs water and forms a soft gel within the bowel, helping to soften stools and make them easier to pass.
Research suggests that psyllium can increase bowel frequency, improve stool consistency and reduce straining. Although the overall quality of the research is considered low, it is still strongly recommended because the benefits appear meaningful and it is generally affordable, accessible and safe when used correctly.
The guidelines suggest that more than 10 g per day may provide the greatest benefit. Start with a smaller amount and gradually increase it over several weeks, following the product instructions. Trial it consistently for at least four weeks.
Psyllium should always be taken with additional fluid. Some people experience bloating or wind when they first begin taking it, particularly if the dose is increased too quickly.
You can add psyllium to drinks, smoothies, or bircher muesli.
3. Prunes
The guidelines suggest trying eight to ten prunes each day. However, the evidence for prunes is less certain than the evidence for psyllium or kiwifruit.
Prunes contain fibre and sorbitol, a naturally occurring carbohydrate that draws water into the bowel.
Prunes may still be a convenient food-based option if you enjoy them. Begin with a smaller amount and gradually increase towards eight to ten per day if tolerated, as they can cause wind, bloating or loose stools.
Try them as a snack like Clare's Muesli Chews, mixed through yoghurt or added to a fruit crumble.
4. Fluids
Drinking enough fluid remains important, particularly when increasing fibre or using psyllium. However, drinking additional plain water does not necessarily relieve chronic constipation if you are already adequately hydrated.
Some research has found that drinking 500 mL to 1.5 L of magnesium and sulfate-rich water each day for two to six weeks may increase the likelihood of experiencing an overall improvement. However, it did not consistently increase bowel frequency or improve other constipation symptoms.
The evidence is still limited, and there is no standard definition of how much mineral content a water needs to have to produce this effect.
What about a high-fibre diet?
Wholegrains, legumes, fruit, vegetables, nuts and seeds remain important parts of a balanced diet and support long-term gut and overall health.
However, there is currently not enough research to conclude that general advice to “eat more fibre” will treat chronic constipation on its own. Fibre isn't unhelpful, however specific strategies such as psyllium and kiwifruit have been studied more carefully and currently have clearer evidence.
Different fibres also behave differently within the bowel. Rapidly increasing fibre can worsen bloating, discomfort or constipation for some people, particularly if fluid intake is inadequate.
So, where should you start?
Choose one option that feels realistic and trial it consistently:
- Kiwifruit may be a good first choice if you prefer food-based strategies or are prone to bloating.
- Psyllium may be helpful if hard stools, infrequent bowel motions or straining are your main concerns.
- Prunes may be worth trying if you enjoy them, although the evidence is less certain.
- High-mineral-content water is an optional alternative and is not necessary alongside the other strategies.
When should you seek medical advice?
Speak with your GP if constipation is persistent, represents a new or unexplained change, or does not improve with simple strategies.
Seek prompt medical attention if constipation occurs alongside:
- Severe or worsening abdominal pain
- Vomiting or a swollen abdomen
- An inability to pass stools or wind
- Blood in your stool
- Unexplained weight loss
- Fever or significant illness
Want to dive deeper into the research? Listen to the Nutrition Science Bites episode with Professor Clare Collins and Professor Kevin Whelan from King's College London and discover the evidence behind how certain foods can help prevent and relieve constipation.
Kevin is a Principle Investigator leading a translational research program exploring the interaction between diet and the gut microbiome in health and disease.
