Kiwifruit, Probiotics May Aid Chronic Constipation, New Guidelines Say

• The British Dietetic Association has released dietary guidelines for chronic constipation.
• These guidelines discuss specific foods, supplements, and drinks that may provide relief.
• Dietitians say other lifestyle choices, such as exercise and stress management, may also help.
• If constipation persists or is accompanied by other symptoms, it’s important to see a doctor.

This condition can disrupt daily life with symptoms like infrequent bowel movements, hard stools, and abdominal discomfort.

While many people turn to dietary changes for relief, past medical guidelines have mostly focused on general advice to eat more fiber or drink enough water, offering little detail on what actually works.

Now, for the first time, the British Dietetic Association (BDA) has developed comprehensive, evidence-based dietary guidelines for adults with chronic constipation, drawing on results from 75 clinical trials. The guidelines were published on October 13 in the Journal of Human Nutrition and Dietetics.

These recommendations identify specific foods, supplements, and drinks that can improve symptoms — and reveal which popular remedies may not help at all.

To create the new guidelines, the BDA convened a Guideline Steering Committee of seven experts in nutrition, dietetics, gastroenterology, and gut physiology.

Their goal was to review the totality of scientific evidence on diet-based approaches for chronic idiopathic constipation in otherwise healthy adults.

Secondary constipation — that’s caused by another condition or medications — was not the focus, though the researchers say the findings may be cautiously applied in those cases.

The team conducted four systematic reviews and meta-analyses, each targeting a different category of dietary intervention:

Only randomized controlled trials (RCTs) were included for supplements, to ensure high-quality evidence.

Other types of intervention trials were also reviewed for foods and drinks, but guideline statements were only made when at least two RCTs supported the finding.

The researchers searched electronic databases between February 2022 and July 2023.

Two reviewers independently screened studies, extracted data, and assessed risk of bias, resolving any differences with additional team members.

Additionally, wherever possible, they pooled results in meta-analyses.

Effect sizes were reported as either risk ratios for binary outcomes (such as the number of people who improved) or mean differences for continuous measures (such as bowel movements per week).

The committee used the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach to rate the quality of evidence — from high to very low — and to determine whether each recommendation should be “strong” or “qualified.”

A strong recommendation meant the intervention was likely to benefit most people with chronic constipation; a qualified recommendation meant benefits might depend more on individual circumstances.

Statements were finalized through a modified Delphi consensus process, requiring at least 85% agreement among committee members.

The guidelines include 59 dietary recommendation statements — 27 strong and 32 qualified — across supplements, foods, and drinks.

Evidence quality was often limited: 66% of statements were based on low-quality evidence, 20% on very low, and only 14% on moderate-quality studies.

Psyllium stood out as the most consistently effective fiber supplement, increasing the number of people who experienced relief, boosting stool frequency, and softening stool consistency.

Some other fibers, like polydextrose or inulin mixtures, did not improve treatment response.

Fiber supplements could increase flatulence, but generally didn’t worsen bloating or abdominal pain.

Overall, probiotics slightly increased the chance of symptom improvement and raised stool frequency, although effects varied widely by strain.

Bifidobacterium lactis increased stool frequency but not consistency, while multi-strain probiotics slightly softened stools.

Few strains showed consistent benefits for global symptoms, and no single strain could be recommended across all outcomes.

Side effects were generally mild and similar to placebo.

Supplements combining probiotics and prebiotics did not improve stool frequency, stool consistency, or global symptoms, based on the small number of available trials.

Magnesium oxide improved both overall constipation symptoms and quality of life, with moderate-quality evidence.

Senna, despite its popularity, showed no consistent benefit for treatment response or stool frequency when results from two trials were combined.

Kiwifruit improved certain symptoms, such as reducing abdominal pain and the sensation of incomplete evacuation, and may be preferred over psyllium for people prone to bloating or gas.

Rye bread increased bowel movements but also slightly worsened overall gastrointestinal symptom scores compared to white bread, though the effect was small and might not matter to all patients.

High mineral–content water — particularly those rich in magnesium and sulfate — was more effective than low-mineral water at helping people achieve softer stools or more frequent bowel movements.

However, it did not improve overall symptoms, abdominal pain, or quality of life compared to low-mineral water.

The mineral content in the studies was far higher than typical U.S. tap water.

Perhaps surprisingly, the researchers found only one RCT examining a high-fiber diet as a whole, and no qualifying evidence for other dietary patterns like the Mediterranean diet. As a result, no recommendations could be made for whole-diet approaches.

Diana Guevara, MPH, RD, a registered dietitian with the Nourish Program at the UTHealth Houston School of Public Health, said that, to support healthy digestion, you should eat a varied, balanced diet containing both prebiotic and probiotic foods. Guevara wasn’t involved in the new guidelines.

“Hydration is also important in supporting healthy digestion because it is used in many processes when your body is breaking down food, and it can also help soften the stool,” Guevara said.

Kristine Dilley, RDN, CSOWM, LD, a registered dietitian nutritionist at The Ohio State University Wexner Medical Center, additionally noted the benefits of taking your time with your meals. Dilley wasn’t involved in the new guidelines.

“Mindful eating that focuses on slowing down and chewing your food well also helps support digestion,” she said.

Dilley said it’s also important to get adequate sleep.

Of course, there are certain situations when diet and lifestyle changes just aren’t enough, and you need to seek professional evaluation to ensure that there isn’t a deeper concern that needs to be addressed.

“Regular medical attention should be pursued for chronic constipation symptoms that last longer than three weeks,” said Dilley.

You would also want to visit a doctor if you have symptoms such as:

• passing stool two or fewer times per week
• unusual changes in the shape, color, or smell of stools
• frequent stomach discomfort or bloating
• unplanned or unexplained weight loss

Dilley advised seeking emergency care if your constipation is accompanied by:

• vomiting
• severe and constant abdominal pain
• sudden or severe abdominal distention (bloating)
• blood in the stool
• fever

By combining evidence-based dietary strategies with healthy lifestyle habits, most people with chronic constipation can find meaningful relief. However, don’t hesitate to seek professional care if needed.