Best Foods to Relieve Constipation: Top 10

The best foods to relieve constipation, led by kiwifruit, prunes and psyllium, add fibre, water or natural sorbitol that softens stools and speeds transit.

Constipation is one of the most common digestive complaints on the planet. A 2025 guideline from the British Dietetic Association estimates that chronic constipation affects about one in ten people worldwide, and the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) puts the figure at roughly 16 in every 100 American adults, rising to 33 in 100 among adults aged 60 and over. Most episodes are mild and short-lived, yet they can make daily life miserable, and many people reach for laxatives before trying the kitchen.

For years, the standard advice was simply to eat more fibre and drink more water. That advice is still broadly sensible, but research published in the last decade has sharpened the picture considerably. Some foods now have randomised controlled trials behind them, with measured doses and measured results, while other popular choices turn out to rest mostly on tradition. This guide, current as of October 2026, ranks ten foods and drinks by the strength of the evidence that they help, explains how each one works, and gives practical serving sizes drawn from clinical trials and from the USDA FoodData Central nutrient database.

A quick note before the list: this article is general information, not medical advice. Constipation that is new, severe, persistent or accompanied by warning signs such as blood in the stool or unexplained weight loss needs a proper assessment by a doctor. The warning signs are listed in full near the end of the article.

How We Chose These Foods

Plenty of lists of constipation remedies exist, and many repeat each other without checking whether the claims hold up. For this ranking, every food had to clear a few hurdles.

• Human evidence: priority went to foods tested in randomised controlled trials of people with constipation, ideally summarised in systematic reviews or clinical guidelines.
• A plausible mechanism: the food needs a known way of working, such as adding bulk, holding water in the stool or delivering a poorly absorbed sugar that draws fluid into the bowel.
• Practicality: the effective amount has to be something a person can realistically eat every day without special equipment.
• Safety: the food should be safe for most adults when introduced gradually, with clear cautions noted where they apply.

The main reference point was the 2025 British Dietetic Association (BDA) guideline on diet for chronic constipation in adults, led by Eirini Dimidi of King's College London. Its authors ran four systematic reviews covering 75 randomised trials, then used the GRADE method and a Delphi survey of experts to produce 59 recommendation statements. Where the guideline was silent, the ranking leaned on individual trials indexed in PubMed and on advice from the NIDDK, the NHS and the Cleveland Clinic.

The order runs from the strongest evidence to the weakest. Foods near the bottom are not useless; they simply have fewer trials behind them, or their benefit comes mainly from their contribution to overall fibre and fluid intake rather than from a specific tested effect. Fibre figures are given per 100 grams and per typical serving, taken from the Standard Reference Legacy dataset in USDA FoodData Central.

At a Glance

1. Kiwifruit

Green kiwifruit sits at the top of this list because it combines good trial evidence with high acceptability. People tend to enjoy eating it, and in head-to-head studies it caused fewer side effects than other fibre-based options. The BDA guideline recommends that adults with chronic constipation try two to three kiwifruit a day for at least four weeks.

Why It Helps

Kiwifruit contains a moderate amount of fibre, about 3 grams per 100 grams according to USDA data, so two fruits deliver only around 4 grams. That modest number hides an important property: kiwifruit fibre holds a large amount of water. A 2018 review in the European Journal of Nutrition attributed the fruit's effect on bowel habits to this water retention capacity, to favourable changes in the gut's microbial community and to actinidin, a natural enzyme that helps break down protein in the stomach and small intestine.

The fruit itself is about 83 percent water. Together these traits soften stool and appear to shorten the time it takes to pass through the colon, without the large fibre load that sometimes leaves people bloated.

What the Research Says

The most cited trial is a 2023 international study published in the American Journal of Gastroenterology. Researchers in New Zealand, Japan and Italy enrolled 184 people, including healthy volunteers, patients with functional constipation and patients with constipation-predominant irritable bowel syndrome (IBS-C). Each person ate two green kiwifruit a day for four weeks and took 7.5 grams of psyllium a day for another four weeks, in random order, with a washout period between.

Kiwifruit produced an increase of about 1.5 complete spontaneous bowel movements per week in people with functional constipation and about 1.7 in those with IBS-C, a change the authors described as clinically relevant. Gastrointestinal comfort also improved, and no significant adverse events were reported.

A US trial by Samuel Chey and colleagues, published in 2021, compared two green kiwifruit a day with 100 grams of prunes and 12 grams of psyllium in 79 patients with chronic constipation over four weeks. All three options increased complete bowel movements. Kiwifruit had the fewest adverse events and the lowest dissatisfaction, and it was the only group to report a significant improvement in bloating.

When the BDA pooled the evidence, kiwifruit and psyllium were similar in the share of people who responded and in stool consistency, while kiwifruit gave a slightly higher stool frequency of about 0.36 extra complete bowel movements per week. The guideline suggests kiwifruit may be the better choice for people who find that psyllium makes them bloated. It is worth knowing that several kiwifruit studies were part-funded by the fruit industry, which the published papers disclose.

How to Eat It

The simplest approach is two fruits a day, eaten at any time. The skin is edible and contains extra fibre, but the BDA notes that skinless kiwifruit can also be recommended, which is useful because many people dislike the fuzzy texture. Cut the fruit in half and scoop out the flesh with a spoon, slice it into breakfast cereal or yogurt, or blend it into a smoothie with a little water.

Give it time. Trials ran for four weeks, and the benefit builds over days rather than hours.

Cautions

Kiwifruit is a recognised food allergen, especially for people with latex allergy or birch pollen allergy, who may notice itching or swelling in the mouth. Anyone with a known allergy should avoid it. The fruit is acidic and can irritate mouth ulcers.

Key Figures

• Dose in guidance: 2 to 3 green kiwifruit a day for at least 4 weeks
• Fibre: about 3.0 g per 100 g, or roughly 4.1 g in two medium fruits (about 138 g)
• Water content: about 83 g per 100 g
• Trial effect (2023): about 1.5 more complete bowel movements per week in functional constipation
• Trial size (2023): 184 participants across three countries

2. Prunes

Prunes, the dried form of certain plum varieties, have been a folk remedy for constipation for generations, and the science largely supports the tradition. The BDA guideline recommends eight to ten prunes a day, which is about 80 to 100 grams.

Why It Helps

Prunes work in more than one way. They are rich in fibre, with USDA data listing about 7.1 grams per 100 grams, and a 2019 laboratory analysis by researchers at King's College London found even higher totals, from 8.4 to 12.0 grams per 100 grams depending on the country of origin.

They also contain a large amount of sorbitol, a sugar alcohol the small intestine absorbs poorly. Unabsorbed sorbitol pulls water into the bowel and is fermented by gut bacteria, both of which soften stool. The same King's College analysis measured 11.2 to 15.5 grams of sorbitol per 100 grams across samples, and an earlier review in Critical Reviews in Food Science and Nutrition listed about 14.7 grams. Prunes are also a source of phenolic compounds such as chlorogenic acid, which may contribute to the effect.

Prune juice is a different product. According to the same review, the juice contains no fibre but keeps some sorbitol, at around 6.1 grams per 100 grams, so it may still help some people, though it delivers less of the whole-fruit benefit.

What the Research Says

A crossover trial published in 2011 in Alimentary Pharmacology and Therapeutics compared 50 grams of prunes twice daily with 11 grams of psyllium twice daily in 40 people with constipation, with three weeks on each. Both regimens provided about 6 grams of fibre a day. Prunes did better than psyllium for the number of complete spontaneous bowel movements and for stool consistency.

A 2019 trial in Clinical Nutrition looked at 120 healthy adults with low fibre intake and infrequent stools who ate either 80 or 120 grams of prunes a day, or drank water only, for four weeks. Stool weight rose by about 22 and 33 grams a day in the two prune groups, and stool frequency also increased compared with the control group. People in the prune groups reported more flatulence.

The BDA's pooled analysis found no clear difference between prunes and psyllium for stool consistency or straining, which places them in the same broad league as one of the best-studied fibre supplements.

How to Eat It

Start with three or four prunes a day and build up over a week or two to the full eight to ten. They can be eaten as a snack, chopped into porridge, simmered with a little water into a soft compote, or blended into a smoothie. Soaking dried prunes overnight makes them plumper and easier to chew.

Cautions

The sorbitol that makes prunes effective can also cause wind, bloating or loose stools, especially if the dose is increased too quickly. People who follow a low-FODMAP diet for irritable bowel syndrome may find prunes troublesome, because sorbitol is one of the polyols that diet limits.

Key Figures

• Dose in guidance: 8 to 10 prunes a day (about 80 to 100 g)
• Fibre: about 7.1 g per 100 g (USDA); 8.4 to 12.0 g per 100 g in a 2019 analysis
• Sorbitol: about 11 to 15 g per 100 g
• One prune weighs about 9.5 g, so ten prunes give roughly 6.7 g fibre
• 2011 crossover trial: 40 participants, prunes beat psyllium on complete bowel movements

3. Psyllium Husk

Psyllium is not a whole food in the usual sense; it is the outer husk of seeds from the Plantago ovata plant, sold as a powder or flakes. It earns a place here because it is the most thoroughly studied fibre for constipation and is easy to add to food or water. In the BDA guideline, psyllium received a strong recommendation, the highest grade given to any fibre product.

Why It Helps

Psyllium is rich in soluble, gel-forming fibre. When it meets water it swells into a thick gel that holds water in the stool, making it softer, bulkier and easier to pass.

What the Research Says

A 2022 systematic review and meta-analysis by Anne van der Schoot and colleagues, published in the American Journal of Clinical Nutrition, pooled 16 randomised trials with 1,251 participants. Fibre supplements of all kinds helped 66 percent of people respond compared with 41 percent on a control, and psyllium was one of the types that showed a clear benefit. The effect was strongest at doses above 10 grams a day taken for at least four weeks.

Based on this work, the BDA guideline recommends fibre supplements at doses above 10 grams a day for at least four weeks, increased gradually and taken with extra fluid. As covered above, kiwifruit and prunes performed similarly to psyllium in head-to-head trials, which gives people a choice of food-based or supplement-based approaches.

Psyllium also has a heart-health role. US federal regulations allow a health claim for foods that provide at least 7 grams a day of soluble fibre from psyllium husk, as part of a diet low in saturated fat and cholesterol, for reduced risk of heart disease.

How to Eat It

Begin with a small amount, such as one teaspoon a day, and increase slowly over one to two weeks. Stir it into a full glass of water or juice and drink it straight away before it thickens. It can also be mixed into porridge, yogurt or soups, or added to bread and muffin dough.

Cautions

Psyllium must be taken with enough liquid, because without it there is a risk of choking or of the fibre forming a blockage. People with difficulty swallowing, or a history of bowel narrowing, should speak to a doctor first. Fibre supplements can affect how some medicines are absorbed, so ask a pharmacist about timing doses. Flatulence and bloating are the most common side effects, and they usually ease as the body adapts.

Key Figures

• Effective dose: more than 10 g of fibre supplement a day for at least 4 weeks
• 2022 meta-analysis: 16 RCTs, 1,251 participants
• Response rate: 66 percent with fibre supplements versus 41 percent with control
• Heart-health claim threshold in US rules: 7 g soluble fibre from psyllium a day
• BDA grade: strong recommendation

4. Rye Bread and Whole Grains

Whole grains are the backbone of a high-fibre diet, and dark rye bread is the grain product with the most direct trial evidence for constipation. The BDA guideline recommends rye bread at six to eight slices a day for at least three weeks, while noting frankly that this amount may be unrealistic for many people.

Why It Helps

Wholegrain rye is rich in cereal fibre that adds bulk to stool and feeds gut bacteria. USDA data give rye bread about 5.8 grams of fibre per 100 grams, roughly 1.9 grams per 32-gram slice, compared with much lower values for refined white bread.

Other whole grains, such as oats, wholewheat bread and pasta, brown rice and barley, work in a similar way and form part of the general advice from the NIDDK and the NHS. Dry rolled oats provide about 10 grams of fibre per 100 grams.

What the Research Says

A 2010 Finnish trial published in the Journal of Nutrition gave 51 adults with constipation whole-grain rye bread (at least 240 grams a day) or white wheat bread for three weeks. Rye bread shortened intestinal transit time by 23 percent, increased the number of bowel movements by about 1.4 a week and made stools softer and easier to pass. The same study found that adding a probiotic did not improve results.

When the BDA pooled two trials of rye bread, which together included 48 people, stool frequency increased by about 0.43 bowel movements a week compared with white bread. Overall symptom scores, however, were slightly worse, possibly because of the extra gas produced when bacteria ferment rye fibre.

How to Eat It

Swap white bread for dark wholegrain rye or wholewheat bread, and switch breakfast cereals to oats, bran flakes or muesli without added sugar. Choose wholewheat pasta and brown rice where possible.

Cautions

People with coeliac disease cannot eat rye, wheat or barley, which all contain gluten. Those with irritable bowel syndrome may find that rye and wheat, which contain fructans, increase bloating. A sudden jump in cereal fibre can cause wind and cramping, so build up slowly over a few weeks.

Key Figures

• Dose in guidance: 6 to 8 slices of rye bread a day for at least 3 weeks
• 2010 trial: 51 adults, transit time 23 percent shorter with rye bread
• Rye bread fibre: about 5.8 g per 100 g, roughly 1.9 g per slice
• Dry oats fibre: about 10.1 g per 100 g
• Pooled BDA analysis: about 0.43 extra bowel movements per week versus white bread

5. Flaxseed and Chia

Small seeds can carry a surprising amount of fibre. Flaxseed, also called linseed, and chia both contain mucilage, a gel-forming fibre that behaves somewhat like psyllium when it meets water. The NHS lists linseed as a simple addition to cereals for people trying to ease constipation.

For a wider look at seeds and their nutrition, see Finepedia's guide to the most nutritious seeds for your diet.

Why It Helps

According to USDA data, flaxseed contains about 27 grams of fibre per 100 grams and chia about 34 grams. Both are rich in a mix of soluble and insoluble fibre. The soluble part forms a gel that softens stool, while the insoluble part adds bulk. They are also good sources of magnesium, with roughly 390 milligrams per 100 grams in flaxseed and 335 milligrams in chia, though a typical serving supplies only a fraction of that.

Ground flaxseed is easier to digest than whole seeds, which can pass through the gut without being broken open.

What the Research Says

Flaxseed has a small but growing body of trials. A 2019 study in Clinical Nutrition ESPEN gave 77 constipated patients with type 2 diabetes cookies containing 10 grams of flaxseed, 10 grams of psyllium or neither, twice a day for 12 weeks. Both fibre groups improved more than the placebo group, and flaxseed produced the larger improvement in constipation symptoms. An earlier trial from the same research group, published in 2018, reported similar findings in 53 patients.

Chia seeds are widely promoted for digestion, and reviews describe how their fibre provides bulk to stool. However, controlled trials specifically testing chia in people with constipation are scarce, so its place here relies mainly on its high fibre content rather than on proven effects.

How to Eat It

Stir one to two tablespoons of ground flaxseed into porridge, yogurt, smoothies or soups. A tablespoon of ground flaxseed weighs about 7 grams and supplies around 1.9 grams of fibre. Chia seeds can be sprinkled on food or soaked in milk or water for about 15 minutes to make a pudding; an ounce (about 28 grams) provides close to 10 grams of fibre.

Cautions

Because these seeds absorb water, they should be eaten with plenty of fluid. Start with small amounts to avoid gas and bloating.

Key Figures

• Flaxseed fibre: about 27.3 g per 100 g, or roughly 1.9 g per tablespoon ground
• Chia fibre: about 34.4 g per 100 g, or roughly 9.8 g per ounce
• 2019 trial: 77 patients, 10 g flaxseed twice daily for 12 weeks
• Magnesium: about 392 mg per 100 g in flaxseed, 335 mg in chia
• Best form of flax: ground, not whole

6. Beans, Lentils and Chickpeas

Pulses are some of the most fibre-dense foods in any kitchen, and they are cheap, filling and versatile. Both the NIDDK and the NHS include legumes such as lentils, black beans, kidney beans and chickpeas among the best sources of fibre for people with constipation.

Why It Helps

A single cup of cooked lentils (about 198 grams) supplies around 15.6 grams of fibre according to USDA data, and a cup of cooked chickpeas (about 164 grams) supplies about 12.5 grams. Cooked black beans contain roughly 8.7 grams per 100 grams. That means one generous serving can cover half or more of the daily fibre target for many adults.

What the Research Says

There are few trials testing pulses alone in people with constipation. Their recommendation rests on their contribution to fibre intake. The NIDDK advises adults to aim for 22 to 34 grams of fibre a day, depending on age and sex, and most people fall well short of that. Pulses are one of the easiest ways to close the gap.

It is worth noting that the BDA guideline made no recommendation for a general high-fibre diet, because trials testing whole-diet changes were lacking. That does not mean fibre is unhelpful. It means the most convincing evidence comes from specific foods and supplements rather than from broad diet advice, and pulses are best seen as a practical source of the fibre that other trials show to be useful.

How to Eat It

Add a handful of cooked lentils to soups and stews, toss chickpeas into salads, or replace part of the meat in chilli or curry with beans. Hummus on wholegrain toast makes an easy snack.

Cautions

Beans are famous for causing wind. Starting with small portions, increasing them slowly, and rinsing canned beans can reduce this. Soaking and thoroughly cooking dried beans is essential, because raw or undercooked red kidney beans contain a natural toxin, phytohaemagglutinin, that can cause severe vomiting and diarrhoea. People with IBS may need to limit pulses, which are high in fermentable carbohydrates.

Key Figures

• Cooked lentils: about 7.9 g fibre per 100 g, or roughly 15.6 g per cup
• Cooked chickpeas: about 7.6 g fibre per 100 g, or roughly 12.5 g per cup
• Cooked black beans: about 8.7 g fibre per 100 g
• Adult fibre target (NIDDK): 22 to 34 g a day
• Main side effect: flatulence, usually easing with regular intake

7. Pears and Apples

Pears and apples are everyday fruits with a double action on the bowel: fibre in the flesh and skin, plus naturally occurring sugars that the gut struggles to absorb. The NHS lists apples among the fruits that contain sorbitol, and both the NIDDK and the NHS recommend apples eaten with the skin as a good source of fibre.

Why It Helps

A medium pear of about 178 grams provides around 5.5 grams of fibre according to USDA data, and a medium apple with its skin, about 182 grams, provides around 4.4 grams. Much of the fibre in apples is pectin, a soluble fibre that the van der Schoot meta-analysis also found to be effective in supplement form.

Pears in particular are rich in sorbitol and fructose. A 2015 systematic review of pears and health reported a typical content of about 4.5 percent fructose and 2.5 percent sorbitol. Because pears and apples contain more fructose than glucose, some of that fructose is poorly absorbed, and together with sorbitol it draws water into the bowel.

What the Research Says

The evidence for pears and apples is largely indirect. The 2015 pear review noted that no human studies had directly tested pears for constipation. The American Academy of Pediatrics, in a 2017 policy statement on fruit juice, observed that the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition suggests using the sorbitol in prune, pear and apple juices to help increase stool frequency and water content in constipated infants.

The BDA guideline also pointed out that earlier guidelines had recommended sorbitol-containing fruits without robust evidence. The sensible conclusion is that pears and apples are healthy, fibre-rich fruits that may help, but they have not been tested as rigorously as kiwifruit or prunes.

How to Eat It

Eat the whole fruit with the skin on, since the skin contains a good share of the fibre. A pear or apple makes a portable snack, and both can be sliced into porridge, baked, or stewed. For infants, any use of fruit juice for constipation should be discussed with a paediatrician first, as juice is generally not recommended before 12 months of age.

Cautions

Sorbitol and excess fructose are FODMAPs, so people with irritable bowel syndrome or fructose malabsorption may experience bloating, gas or diarrhoea. Fruit juice lacks most of the fibre of whole fruit and is high in sugar, so whole fruit is the better everyday choice.

Key Figures

• Medium pear (178 g): about 5.5 g fibre
• Medium apple with skin (182 g): about 4.4 g fibre
• Pear composition: about 4.5 percent fructose and 2.5 percent sorbitol
• Pear water content: about 84 g per 100 g
• Direct human trials of pears for constipation: none identified in a 2015 review

8. Berries

Raspberries, blackberries and other berries are among the highest-fibre fresh fruits available. The NIDDK names berries specifically among the fruits that are good sources of fibre, and the Cleveland Clinic includes them in its list of high-fibre fruits for people with constipation.

Why It Helps

USDA data show raspberries contain about 6.5 grams of fibre per 100 grams, giving roughly 8 grams per cup, while blackberries provide about 5.3 grams per 100 grams, or roughly 7.6 grams per cup. Strawberries are lower, at about 2.0 grams per 100 grams, but are still a useful contribution. Much of the fibre comes from the tiny seeds, which are mostly insoluble and add bulk to stool.

Berries are also high in water, and the NHS lists raspberries and strawberries among the fruits that contain sorbitol.

What the Research Says

There are no large trials testing berries alone as a treatment for constipation. Their value lies in their high fibre-to-calorie ratio, which makes them an easy way to raise overall fibre intake toward the 22 to 34 grams a day the NIDDK recommends for adults.

How to Eat It

Add a cup of fresh or frozen berries to breakfast cereal, porridge or yogurt, blend them into smoothies, or eat them as a snack. Frozen berries are usually cheaper than fresh, keep for months, and retain their fibre.

Cautions

Berries are generally well tolerated. People who have been told to avoid seeds because of past diverticulitis should follow their own doctor's advice. Wash fresh berries before eating them. Some people find that large servings of strawberries or raspberries cause wind because of their sorbitol content.

Key Figures

• Raspberries: about 6.5 g fibre per 100 g, roughly 8.0 g per cup (123 g)
• Blackberries: about 5.3 g fibre per 100 g, roughly 7.6 g per cup (144 g)
• Strawberries: about 2.0 g fibre per 100 g
• Main fibre source: the seeds, which are largely insoluble
• Typical serving: 1 cup, fresh or frozen

9. Leafy Greens and Vegetables

Vegetables are a cornerstone of any diet that keeps the bowel healthy. The NIDDK lists carrots, broccoli, green peas and collard greens among good fibre sources, and the NHS advises people with constipation to eat more fruit and vegetables generally.

For older adults, who are more prone to constipation, Finepedia's list of healthy foods for senior citizens covers several of these vegetables in more detail.

Why It Helps

Leafy greens and other vegetables combine fibre with a high water content. USDA data put raw spinach at about 2.2 grams of fibre per 100 grams, raw kale at about 4.1 grams and raw broccoli at about 2.6 grams. A cup of chopped raw broccoli (about 91 grams) supplies roughly 2.4 grams of fibre, while a cup of raw spinach (about 30 grams) supplies only around 0.7 grams, because the leaves are so light.

Cooking greens shrinks their volume, so a cooked portion packs in more fibre than the same cup of raw leaves.

What the Research Says

Trials testing specific vegetables against constipation are rare. As with pulses and berries, the case for vegetables rests on their role in reaching a healthy fibre intake. A plate that is half vegetables, as many dietary guidelines advise, makes it much easier to hit the 22 to 34 grams a day suggested for adults.

How to Eat It

Aim to fill half your plate with vegetables at main meals. Add a handful of spinach to omelettes, curries or pasta sauces, roast broccoli and carrots, and include peas or sweet potatoes as side dishes. Soups and stews are an easy way to eat several vegetables at once.

Cautions

People taking the blood thinner warfarin should keep their intake of vitamin K-rich greens such as kale and spinach steady from day to day, rather than suddenly increasing it, and should talk to their doctor before making big changes. Large amounts of raw cruciferous vegetables such as broccoli and cabbage can cause gas in some people.

Key Figures

• Raw kale: about 4.1 g fibre per 100 g
• Raw broccoli: about 2.6 g fibre per 100 g, roughly 2.4 g per chopped cup
• Raw spinach: about 2.2 g fibre per 100 g, roughly 0.7 g per cup
• Plate guide: about half the plate as vegetables at main meals
• NIDDK examples: carrots, broccoli, green peas, collard greens

10. Mineral-Rich Water and Fluids

Water is not a food, but no list about constipation is complete without it. Fibre needs fluid to work: without enough water, extra fibre can make stools harder rather than softer. The NIDDK, the NHS and the Cleveland Clinic all advise drinking plenty of liquids, especially when increasing fibre.

Why It Helps

The colon's main job is to absorb water from digested food. As the Cleveland Clinic explains, when waste moves slowly, the colon removes too much water and the stool becomes hard and dry. Adequate fluid helps keep stool soft and lets fibre swell properly.

Some natural mineral waters contain high levels of magnesium and sulfate, which have an osmotic laxative effect, drawing water into the bowel. In the trials reviewed by the BDA, the waters contained 105 to 1,000 milligrams of magnesium and 1,530 to 2,000 milligrams of sulfate per litre. For comparison, UK tap water typically contains only about 0.6 to 32 milligrams of magnesium per litre.

What the Research Says

A 1998 Italian trial gave 117 adults with chronic functional constipation a diet providing about 25 grams of fibre a day for two months. One group drank as much as they liked, while the other was asked to drink 2 litres of mineral water a day. Both groups improved, but the group drinking more water had a significantly greater increase in stool frequency and a larger drop in laxative use. The authors concluded that raising fluid intake to 1.5 to 2 litres a day enhanced the effect of fibre.

For high-mineral water specifically, the BDA pooled three trials with 539 participants and found that 47 percent more people responded to treatment compared with low-mineral water, although stool frequency itself did not differ. The guideline suggests 0.5 to 1.5 litres a day for two to six weeks.

How to Eat It

Keep a glass or bottle of water within reach through the day, and drink more in hot weather or when exercising. If you want to try a high-mineral water, check the label for the magnesium and sulfate content; there is no need to choose a particular brand.

Warm drinks in the morning can also help some people. Finepedia's article on the health benefits of coffee covers the research on coffee and the gut.

Cautions

People with heart failure, kidney disease or other conditions that require fluid restriction must follow their doctor's advice on how much to drink. High-magnesium water may not suit people with kidney problems. Alcohol can worsen dehydration, which is why the NHS advises cutting back on it during constipation.

Key Figures

• High-mineral water dose in guidance: 0.5 to 1.5 L a day for 2 to 6 weeks
• Pooled BDA analysis: 3 RCTs, 539 participants, 47 percent higher response rate
• Magnesium in studied waters: 105 to 1,000 mg per litre
• Magnesium in UK tap water: about 0.6 to 32 mg per litre
• 1998 trial: 2 L of mineral water a day boosted the effect of a 25 g fibre diet

Fibre per Serving Compared

The table below compares the fibre in typical servings of the foods on this list. All values come from the Standard Reference Legacy dataset in USDA FoodData Central and are rounded to one decimal place. Actual values vary by variety, ripeness and preparation.

What About Probiotics and Fermented Foods?

Yogurt, kefir and other fermented foods are often suggested for constipation. The evidence is less clear than for the foods above. The BDA guideline reviewed 30 probiotic trials with 2,804 participants and concluded that probiotics may help overall, but it was not possible to say which specific strains work. Several common types, including multistrain products and Bifidobacterium lactis, showed no effect on the share of people who responded.

A small Turkish pilot study published in 2014 gave 20 patients 500 millilitres of kefir a day for four weeks and reported more frequent, softer stools, but it had no control group, and the authors called for controlled trials. Fermented dairy can be part of a healthy diet, but it should not replace the better-tested options in this list.

Foods and Habits That Can Make It Worse

Some eating habits make constipation more likely. Diets low in fibre and high in refined, processed foods are a common culprit; Finepedia's guide to unhealthy foods to limit and better swaps covers many of these. The Cleveland Clinic notes that large amounts of milk and cheese may contribute in some people, and both it and the NHS mention that alcohol can worsen dehydration.

Medicines are another frequent cause. The NIDDK lists opioid painkillers, iron supplements and antacids containing aluminium or calcium among the medications that can cause constipation. Anyone who suspects a medicine is to blame should talk to their doctor or pharmacist rather than stopping it on their own.

When to See a Doctor

Diet changes help many people, but some symptoms need medical attention. According to the NIDDK, you should see a doctor right away if constipation comes with any of the following:

• Bleeding from the rectum or blood in the stool
• Constant pain in the abdomen
• Inability to pass gas
• Vomiting or fever
• Lower back pain
• Losing weight without trying

The NHS also advises seeing a GP if constipation is not improving with self-help, keeps coming back, or if you notice a sudden change in bowel habits or persistent tiredness. A family history of colon or rectal cancer is another reason to get checked. This article is for general information only and is not a substitute for professional medical advice.

Frequently Asked Questions

What is the fastest food to relieve constipation?

No food works within minutes. Prunes and kiwifruit tend to show effects within days, but trials measured benefits over three to four weeks. Prune juice and high-mineral water may act a little faster for some people. If you need quick relief, ask a pharmacist about suitable short-term laxatives and keep adding fibre gradually.

How many prunes should I eat a day for constipation?

The 2025 British Dietetic Association guideline suggests 8 to 10 prunes a day, roughly 80 to 100 grams. Start with three or four and increase over a week or two to limit wind and bloating. Drink plenty of water alongside, and reduce the amount if stools become too loose.

Is kiwifruit better than psyllium for constipation?

In trials, two kiwifruit a day performed about as well as psyllium, with slightly more frequent bowel movements and fewer side effects such as bloating. Psyllium has more studies and a strong guideline recommendation. Both are reasonable choices, and people who feel bloated on psyllium may prefer kiwifruit instead.

How much fibre do I need each day?

The NIDDK advises adults to aim for 22 to 34 grams of fibre a day, depending on age and sex, and children 14 to 31 grams. Many people eat far less. Raise intake gradually over several weeks, mixing fruit, vegetables, whole grains, pulses and seeds, and drink more fluid as you go.

Can drinking more water cure constipation?

Water alone rarely cures chronic constipation, but it helps fibre work. In a 1998 trial, people eating 25 grams of fibre daily improved more when they also drank 2 litres of water a day. High-mineral waters rich in magnesium and sulfate showed extra benefit in some trials. Follow medical advice if your fluids are restricted.

Are bananas good or bad for constipation?

Bananas contain a moderate amount of fibre and are generally fine to eat. Popular belief holds that unripe bananas can be binding, while ripe bananas are less likely to cause problems, but there is little strong trial evidence either way. If bananas seem to worsen your symptoms, swap them for kiwifruit, pears or berries.

Conclusion

The idea that diet can relieve constipation is not new, but the evidence behind it has become much more precise. As of October 2026, the best-supported choices are two to three kiwifruit a day, eight to ten prunes, or a psyllium supplement of more than 10 grams a day, each given at least three to four weeks to work. Rye bread, flaxseed and high-mineral water have smaller but real bodies of evidence, while beans, fruits, berries and vegetables help mainly by raising overall fibre intake toward the recommended 22 to 34 grams a day.

Whatever you choose, introduce it gradually, drink enough fluid and give it time. If constipation persists or comes with warning signs, see a doctor rather than relying on food alone.