British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults

British Dietetic Association (BDA) · 2025 · United Kingdom

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Authors: Eirini Dimidi, Alice van der Schoot, Kevin Barrett et al.
Title: British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults
Journal: Journal of Human Nutrition and Dietetics, 2025
DOI: 10.1111/jhn.70133
Licence: CC BY 4.0
Changes: Verbatim excerpts; formatting adapted

Full text retrieved 2026-10-27 from Europe PMC · PMC12517116

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Recommendations

Verbatim, with grade of recommendation or strength of consensus where given.

Results

1. Specific types of fibre supplements increase the number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias, inconsistency, and imprecision. Upgraded for dose‐response effect.
1.1. Psyllium supplements increase the number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias, imprecision.
1.2. Polydextrose, mixtures of inulin and other fibres, and galacto‐oligosaccharide supplements do not impact the number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Polydextrose: Downgraded due to imprecision. Mixtures of inulin and other fibres: Downgraded due to high risk of bias, inconsistency, and imprecision. Galacto‐oligosaccharides: Downgraded due to imprecision.
2. Specific types of fibre supplements increase stool frequency and soften stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Stool frequency: Downgraded due to high risk of bias and inconsistency. Upgrade due to dose response effect. Stool consistency: Downgraded due to high risk of bias, imprecision, possible publication bias. Upgraded due to dose–response effect.
2.1. Psyllium supplements increase stool frequency and soften stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Stool frequency: Downgraded due to high risk of bias and imprecision. Upgraded due to large magnitude of effect. Stool consistency: Downgraded due to high risk of bias and imprecision.
2.2. Inulin‐type fructan supplements do not impact stool frequency in constipation, but soften stool consistency.Quality of evidence: Low; Reason for quality of evidence grade: Stool frequency and inconsistency: Downgraded due to high risk of bias and imprecision.
2.3. Mixtures of inulin and other fibre supplements do not impact stool frequency in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Downgraded due to high risk of bias, inconsistency, and imprecision.
2.4. Polydextrose and galacto‐oligosaccharide supplements do not impact stool frequency or stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Polydextrose: Stool frequency and consistency: downgraded due to imprecision. Galacto‐oligosaccharides: Stool frequency and consistency: downgraded due to inconsistency and imprecision.
3. Overall, fibre supplements do not impact global symptoms of constipation, but specific types of fibre supplements improve specific symptoms of constipation.Quality of evidence: Low; Reason for quality of evidence grade: Global symptoms: Downgraded due to high risk of bias. Straining (severity): Downgraded due to high risk of bias and imprecision. Upgraded for dose response effect. Incomplete evacuation (severity): Downgraded due to high risk of bias and imprecision.
3.1. Psyllium supplements reduce the severity of straining in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
3.2. Polydextrose supplements do not impact global symptoms or specific symptoms of constipation.Quality of evidence: Low; Reason for quality of evidence grade: Global symptoms and straining (severity): Downgraded due to imprecision.
3.3. Galacto‐oligosaccharide supplements do not impact global symptoms of constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to imprecision.
4. Specific types of fibre supplements increase the severity of flatulence in constipation, but not bloating or abdominal pain/discomfort.Quality of evidence: Low; Reason for quality of evidence grade: Flatulence, bloating, abdominal pain/discomfort: Downgraded due to high risk of bias and imprecision.
4.1. Inulin‐type fructan supplements increase the severity of flatulence in constipation, but not bloating.Quality of evidence: Low; Reason for quality of evidence grade: Flatulence and bloating: Downgraded due to high risk of bias and imprecision.
5. Polydextrose supplements do not impact global or specific components of quality of life in constipation.Quality of evidence: Moderate; Reason for quality of evidence grade: All downgraded for imprecision.
6. Probiotics overall may increase the number of people with constipation who have a clinical benefit, though it is unclear which species or strains are effective.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
6.1. Multi‐strain probiotic supplements, Bifidobacterium lactis supplements, and Bacillus coagulans supplements do not impact the number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Multi‐strain probiotics and B. lactis: Downgraded due to high risk of bias and imprecision. B. coagulans: Downgraded for imprecision.
7. Probiotics overall, and some specific species, increase stool frequency, but do not impact stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Stool frequency: Downgraded due to high risk of bias and inconsistency. Stool consistency: Downgraded due to high risk of bias and potential publication bias.
7.1. Multi‐strain probiotic supplements do not impact stool frequency in constipation, but soften stool consistency.Quality of evidence: Low; Reason for quality of evidence grade: Stool frequency: Downgraded due to high risk of bias. Stool consistency: Downgraded due to high risk of bias and imprecision.
7.2. Bifidobacterium lactis supplements increase stool frequency in constipation, but do not impact stool consistency.Quality of evidence: Moderate; Reason for quality of evidence grade: Stool frequency and consistency: Downgraded due to high risk of bias.
7.3. Bacillus coagulans Unique IS2 supplements do not impact stool frequency or stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Stool frequency and consistency: Downgraded due to inconsistency and imprecision.
7.4. Lactobacillus casei Shirota supplements do not impact stool frequency or stool consistency in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Stool frequency and consistency: Downgraded due to high risk of bias, inconsistency and imprecision.
8. Probiotics overall improve global symptoms of constipation, but not the majority of individual symptoms, though it is unclear which species or strains are effective.Quality of evidence: Very low; Reason for quality of evidence grade: Global: Downgraded due to high risk of bias and inconsistency. Straining (severity): Downgraded due to high risk of bias. Incomplete evacuation (severity): Downgraded due to high risk of bias. Upgraded due to large magnitude of effect. Straining, manual manoeuvres, anorectal obstruction (frequency): Downgraded due to high risk of bias and imprecision. Incomplete evacuation (frequency): Downgraded due to high risk of bias, inconsistency and imprecision. Manual manoeuvres (frequency): Downgraded due to high risk of bias and imprecision.
8.1. Multi‐strain probiotic supplements do not impact global symptoms of constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
8.2. Bifidobacterium lactis supplements do not impact global symptoms or specific symptoms of constipation.Quality of evidence: Low; Reason for quality of evidence grade: Global: Downgraded due to imprecision. Straining (severity): Downgraded due to imprecision. Incomplete evacuation (severity): Downgraded due to high risk of bias and imprecision.
8.3. B. coagulans Unique IS2 supplements improve specific symptoms of constipation.Quality of evidence: Low; Reason for quality of evidence grade: Incomplete evacuation, defecation pain (frequency): Downgraded due to inconsistency and imprecision.
8.4. Lactobacillus casei Shirota supplements do not impact global symptoms of constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Downgraded due to high risk of bias, inconsistency, and imprecision.
9. Probiotics overall reduce the severity of flatulence in constipation, but do not impact abdominal pain/discomfort or bloating, though it is unclear which species or strains are effective.Quality of evidence: Low; Reason for quality of evidence grade: Flatulence: Downgraded due to high risk of bias and imprecision. Abdominal pain/discomfort: Downgraded due to high risk of bias. Bloating: Downgraded due to high risk of bias and inconsistency.
9.1. Multi‐strain probiotic supplements do not impact the severity of flatulence, abdominal pain/discomfort or bloating in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Flatulence: Downgraded due to high risk of bias and imprecision. Abdominal pain/discomfort: Downgraded due to high risk of bias and imprecision. Bloating: Downgraded due to high risk of bias, inconsistency, and imprecision.
9.2. Bifidobacterium lactis supplements do not impact the severity of abdominal pain or bloating in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Abdominal pain: Downgraded due to imprecision. Bloating: Downgraded due to high risk of bias, inconsistency, and imprecision.
9.3. Bacillus coagulans Unique IS‐2 supplements decrease frequency of abdominal pain in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to inconsistency and imprecision.
9.4. Lactobacillus casei Shirota supplements do not impact the severity of bloating in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
10. Probiotics overall do not impact global or specific components of quality of life in constipation.Quality of evidence: Low; Reason for quality of evidence grade: All downgraded due to high risk of bias and imprecision.
10.1. Multi‐strain probiotic supplements do not impact global quality of life in constipation, but improve specific components of quality of life.Quality of evidence: Low; Reason for quality of evidence grade: All downgraded due to high risk of bias and imprecision.
10.2. Bifidobacterium lactis supplements do not impact global or specific components of quality of life in constipation.Quality of evidence: Moderate; Reason for quality of evidence grade: All downgraded due to imprecision.
11. Synbiotics do not impact stool frequency or stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to inconsistency and imprecision.
12. Synbiotics do not impact global symptoms of constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Downgraded due to high risk of bias, inconsistency, and imprecision.

Magnesium oxide supplements

13. Magnesium oxide supplements increase the number of people with constipation who have a clinical benefit.Quality of evidence: Moderate; Reason for quality of evidence grade: Downgraded due to imprecision.
14. Magnesium oxide supplements increase stool frequency and soften stool consistency in constipation.Quality of evidence: Moderate; Reason for quality of evidence grade: All downgraded due to imprecision.
15. Magnesium oxide supplements improve global symptoms, as well as the severity of straining and the sense of incomplete evacuation in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Global symptoms and incomplete evacuation: Downgraded due to imprecision. Straining: Downgraded due to inconsistency and imprecision.
16. Magnesium oxide supplements reduce the severity of bloating and abdominal discomfort in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Bloating: Downgraded due to imprecision. Abdominal discomfort: Downgraded due to inconsistency and imprecision.
17. Magnesium oxide supplements improve global and specific components of quality of life in constipation.Quality of evidence: Moderate; Reason for quality of evidence grade: All downgraded due to imprecision.
18. Senna supplements do not impact number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to inconsistency and imprecision.
19. Senna supplements do not impact stool frequency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to inconsistency and imprecision.
20. Kiwifruit supplements do not impact stool frequency or stool consistency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: All downgraded due to inconsistency and imprecision.
21. Kiwifruit supplements improve specific symptoms of constipation only.Quality of evidence: Very low; Reason for quality of evidence grade: All downgraded due to high risk of bias, inconsistency, and imprecision.
22. Kiwifruit supplements reduce the frequency of abdominal pain in constipation, but not flatulence or bloating.Quality of evidence: Very low; Reason for quality of evidence grade: Abdominal pain and bloating: Downgraded due to high risk of bias and imprecision. Flatulence: Downgraded due to high risk of bias, inconsistency, and imprecision.

Kiwifruits and prunes

23. There is no difference between kiwifruit and psyllium in the number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
24. Kiwifruit is more effective at increasing stool frequency, but not improving stool consistency, compared with psyllium, in constipation.Quality of evidence: Low; Reason for quality of evidence grade: All downgraded due to high risk of bias and imprecision.
25. There is no difference between prunes and psyllium on stool consistency in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
26. There is no difference between kiwifruits and psyllium on frequency of straining in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Downgraded due to high risk of bias, inconsistency, and imprecision.
27. There is no difference between prunes and psyllium on severity of straining in constipation.Quality of evidence: Very low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
28. Rye bread is more effective than white bread at increasing stool frequency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
29. Rye bread worsens global symptoms of constipation compared to white bread.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
30. High mineral‐content water is more effective than low mineral‐content water at increasing the number of people with constipation who have a clinical benefit.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.
31. There is no difference between high mineral‐content water compared to low mineral‐content water on stool frequency in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and inconsistency.
32. There is no difference between high mineral‐content water and low mineral‐content water on global symptoms of constipation.Quality of evidence: Moderate; Reason for quality of evidence grade: Downgraded due to imprecision.
33. There is no difference between high mineral‐content water and low mineral‐content water on the severity of abdominal pain in constipation.Quality of evidence: Moderate; Reason for quality of evidence grade: Downgraded due to high risk of bias.
34. There is no difference between high mineral‐content water and low mineral‐content water on global quality of life in constipation.Quality of evidence: Low; Reason for quality of evidence grade: Downgraded due to high risk of bias and imprecision.

Research Recommendations

Probiotic supplements: It is still unclear which strains of probiotics are effective in constipation. Further well‐designed RCTs examining the effect of appropriately characterised probiotic strains in chronic constipation are needed.
Synbiotic supplements: The evidence for synbiotic supplements in chronic constipation is sparse. Further RCTs examining different combinations of probiotic and prebiotic/fibre supplements in chronic constipation are needed.
Prunes: Evidence from a systematic review and meta‐analysis of RCTs suggests that prunes are not more effective than psyllium in improving constipation outcomes [14]. Psyllium is itself an effective treatment for chronic constipation. However, these studies did not follow a truly comparative evaluation design in that studies were not equivalence trials; hence, it is not possible to conclude that prunes are as effective as psyllium. Future studies are needed to establish the effectiveness of prunes in people with chronic constipation, either through a placebo‐controlled RCT or an appropriately designed equivalence RCT compared with psyllium or other effective interventions.
Fermented foods: There is increased interest in research into the use of fermented foods to improve chronic constipation. For example, a few small non‐randomised and uncontrolled trials on kefir have been undertaken, indicating potential beneficial effects on constipation [22, 23]. High‐quality RCTs are now required to establish the impact of fermented foods, such as kefir, in people with constipation.
Food products with inactivated bacteria: There is little research on the effect of food products with inactivated bacteria in chronic constipation. An RCT of pasteurised yoghurt with inactivated bacteria showed promising effects on the relief of constipation symptoms [24]. Future studies are needed to establish the effectiveness of food products with inactivated bacteria in people with constipation.
High fibre foods and diets: An increase in fibre intake is often recommended in the management of chronic constipation, alongside additional fluid intake [9, 25]. The vast majority of evidence is for fibre supplements, not high fibre foods or diets. There is promising evidence from single RCTs and uncontrolled trials of different high fibre foods in constipation (e.g., mango, figs, oat bran, high fibre cereal, and flaxseed flour [14]) that warrant adequately powered and appropriately controlled RCTs.
While some studies exist on high fibre foods in chronic constipation, there are currently no RCTs evaluating the effect of a high fibre diet from a range of foods in the diet in chronic constipation. Future RCTs are required to establish whether high fibre diets are effective in chronic constipation, and whether any beneficial effects might be enhanced with appropriate concurrent fluid intake.
Additional fluids: There is currently a lack of evidence to support that additional fluid consumption alone is beneficial in chronic constipation. Only one study of water supplementation (2 L/d) alongside a diet containing 25 g/d fibre has been performed and was effective in increasing stool frequency and decreasing laxative use in chronic constipation, compared to control [26]. Future RCTs are needed to establish whether increasing fluid intake beyond habitual levels is effective in chronic constipation.
Caffeine: No RCTs have been conducted on the effect of caffeine on chronic constipation, and future trials are needed to establish this.
Senna: Senna is a popular treatment in constipation, and its use has been recommended previously in guidelines [9]. Despite two placebo‐controlled RCTs individually demonstrating effectiveness of senna supplements on constipation outcomes, compared to placebo, when these were meta‐analysed together, the overall effect was no longer significant, albeit with significant heterogeneity [11]. The many remaining studies of senna include numerous uncontrolled trials. Future high‐quality placebo‐controlled RCTs are needed to establish the effectiveness of senna supplements in chronic constipation.
Vitamin C: Anecdotally, vitamin C has been hypothesised to improve symptoms of chronic constipation. This originates from the fact that a possible side effect of high doses of vitamin C is diarrhoea, and hence, it may have a laxative effect in people with constipation [27]. However, no RCTs investigating the effect of vitamin C in chronic constipation have been conducted. Thus, RCTs are needed to assess the impact of vitamin C in people with chronic constipation.
Trigger foods: Although several foods (e.g., rice, bananas) are widely perceived to worsen constipation symptoms [28], there is very limited research to support such claims. RCTs are needed to identify dietary components, food, diets and dietary behaviours that may trigger or worsen symptoms of constipation.

Abstract

Background: Current clinical guidelines for chronic constipation offer limited dietary recommendations. The aim of this project was to develop the first comprehensive evidence‐based dietary guidelines for the management of chronic constipation in adults.

Methods: Four systematic reviews and meta‐analyses were performed to identify eligible randomised controlled trials (RCTs). The findings generated from the meta‐analyses were then used to develop guideline statements using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach and a Delphi consensus survey among a multi‐disciplinary expert Guideline Steering Committee. Recommendation statements were produced for treatment response, stool output, gut symptoms, adverse events, and quality of life, and only based on the findings where ≥ 2 RCTs contributed to the meta‐analysis. The strength of recommendation was assessed using the GRADE approach. Consensus voting amongst the Guideline Steering Committee was performed using a modified Delphi survey approach.

Results: The four systematic reviews included a total of 75 RCTs. Fifty‐nine dietary recommendation statements were generated and accepted through the Delphi survey. For dietary supplements, 15 recommendation statements relate to fibre supplements, 20 relate to probiotics, 2 to synbiotics, 5 to magnesium oxide, 2 to senna, and 3 to kiwifruit supplements. For foods, three recommendation statements related to kiwifruits, two to prunes, and two to rye bread. For drinks, five recommendation statements related to high mineral‐containing water. No recommendations were made for whole diet approaches due to a lack of evidence. Twelve statements had a very low level of evidence, 39 had a low level of evidence, and 8 had moderate evidence. Twenty‐seven statements were strong recommendations, and 32 were qualified recommendations.

Conclusions: These are the first comprehensive evidence‐based dietary guidelines for the management of constipation based upon a robust systematic review and GRADE processes. Recommendations were made for dietary supplements, foods and drinks that have never been previously included in clinical guidelines, and can now be rapidly implemented into clinical practice, thereby improving clinical care and patient outcomes.

Contents of the original publication

The section headings of the original.

Introduction
Materials and Methods
Scope of the Dietary Guidelines
Systematic Reviews and Meta‐Analyses for Evidence Generation
Development of Recommendation Statements
GRADE
Delphi Consensus Survey
Guideline Endorsement
Results
Fibre Supplements
Probiotic Supplements
Synbiotic Supplements
Food Supplements
Magnesium Oxide Supplements
Senna Supplements
Kiwifruit Supplements
Foods and Drinks
Fruits
Rye Bread
High Mineral‐Content Water
Whole Diet Interventions
Research Recommendations
Discussion
Peer Review
Supporting information

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