After conducting a comprehensive systematic review spanning 75 randomized controlled trials, the BDA compiled 59 dietary recommendation statements, including 27 positive recommendations.
Psyllium supplements, magnesium oxide supplements and certain probiotic strains were endorsed, alongside kiwifruits, rye bread and high-mineral content water. In contrast, previously recommended strategies such as senna supplements and high fiber diets were rejected due to a lack of evidence.
However, while Dr. Eirini Dimidi, who led the guidelines, said the guidance reveals some new, helpful strategies, gaps in the literature remain.
“Chronic constipation can have a huge impact on someone’s day-to-day life,” she said in a press statement. “Our research reveals some new dietary strategies that could indeed help patients. At the same time, we urgently need more high-quality trials to strengthen the evidence on what works and what doesn’t.”
How common is constipation?
Around one in 10 people suffer with chronic constipation, which is typically characterized by ‘unsatisfactory defecation’ that results from infrequent stools and/or difficult stool passage.
Chronic constipation can significantly impact quality of life and add financial strain on healthcare systems, yet nearly half of people with this condition are not satisfied with the current treatment options.
Until now, constipation guidelines almost exclusively focused on increasing fiber and fluid intake, something Dimidi et al. described as vague and limited.
“There is a lack of comprehensive dietary guidelines for the management of chronic constipation that represent the totality of the available evidence and provide practical recommendations for clinical practice,” they wrote in the Journal of Human Nutrition and Dietetics. “This interferes with the advice given by healthcare professionals, ultimately negatively impacting patients’ symptom management and overall satisfaction.”
To address this gap, the authors completed a systematic review of the literature and conducted a consensus process with the help of an expert guideline steering committee.
Now, the new guidelines offer recommendations for various dietary interventions that have not been included previously, moving beyond traditional high fiber messaging to provide practical, evidence-based recommendations on foods, drinks and dietary supplements.
Which supplements have the strongest scientific backing?
In terms of dietary supplements, three received positive recommendations. Magnesium oxide supplements were found to have the largest range of benefits, increasing stool frequency, softening stool consistency and reducing straining severity, bloating and abdominal discomfort.
These supplements, which were also found to improve various quality of life measures, are recommended at a dose of 0.5-1.5 grams per day for at least four weeks, with the dosage increased gradually in weekly increments if necessary.
Psyllium supplements were also backed by strong evidence for increasing stool frequency, softening stool consistency and reducing straining severity, but there was a lack of evidence to support any quality of life improvements.
Finally, probiotics received a positive recommendation overall. However, while some RCTs showed improvements with species and strains such as B. lactis and Bacillus coagulans, when the data was meta-analysed together, no single probiotic was found to be effective in increasing response to treatment.
The guidelines therefore do not recommend any specific probiotic species or strains. Instead, they suggest clinicians support patients who wish to try probiotics and advise them to try a probiotic brand of their choice for at least four weeks to assess for any changes.
While kiwifruits, rye bread and high-content mineral water also received positive recommendations, there was a lack of evidence to support synbiotics, kiwifruit and senna supplements, and fiber supplements such as polydextrose, inulin-type fructans and galacto-oligosaccharides.
Dimidi et al. say this reflects a critical data gap, with a lack of high-quality clinical trials available to showcase their potential benefits.
Is a ‘food-first’ approach still necessary?
However, Dr. Emma Derbyshire, a registered public health nutritionist and CEO of Nutritional Insight, said there are some potential shortcomings.
First is the definition of chronic constipation itself. Rather than the ‘unsatisfactory defecation’ definition, Derbyshire argues the Rome IV Criteria of functional constipation should have been used to inform the guidelines, particularly to differentiate between mild and longer-term functional constipation.
She also highlighted the importance of a food-first approach to prevent symptoms from returning once supplementation ceases.
“We should ideally focus on closing fiber gaps first and getting to the root of the problem,” she told NI. “Food-based strategies should be prioritized […], otherwise, supplements can become a ‘quick fix’, and symptoms may return once they’re stopped if basic dietary changes haven’t been made.”
Finally, she highlighted practical challenges such as affordability, with some consumers priced out of higher-end products such as high-mineral content water.
“In the evidence-base, it is well known that any old water can help to soften stools and prevent constipation,” she said. “So, from a practical sense simply making sure that those with chronic constipation are drinking enough water and meeting daily fluid intake guidelines would be a broader and easier recommendation to achieve.”
Source: Journal of Human Nutrition and Dietetics. doi: 10.1111/jhn.70133. “British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adult.” Authors: E. Dimidi, et al.
