Updated BDA constipation recommendations and the Root To Tip initiative: a dietitian’s perspective
The British Dietetic Association (BDA) recently published updated clinical guidance on the management of chronic constipation.[1] The new guidelines have more focus on the key foods, drinks and supplements that help alleviate chronic constipation and will underpin dietetic advice provided for this condition.[2] Along with this new guidance, I have been reading around reducing food wastage, which has led me to a recent campaign involving increasing the use of all edible parts of fruit and vegetables: the Root To Tip project by King’s College London.[3,4]
What is dietary fibre?
Dietary fibre is characterised as a form of carbohydrate that is found naturally in plants that we eat, eg fruit and vegetables. Unlike sugars and starches, fibre is not digested in the small intestine and remains intact until it reaches the large intestine. It is then broken down by gut bacteria and helps stools stay soft and easy to pass on via defecation.[5,6] Current recommendations are that we need 30g fibre a day for healthy bowel function.[2,4-6]
What is chronic constipation?
Chronic constipation is a common but distressing disorder defined by infrequent defecation, difficulty passing stools or the sensation of incomplete bowel emptying.[4] Reported to affect around 3% to 27% of people within the general population, it is more prevalent in women.[5,7,8] It can have a significant impact on someone's quality of life.[8,9] Causes of chronic constipation are numerous, including:
Not eating enough fibre and not drinking enough fluid
Inactivity
Often ignoring the urge to go to the toilet
Side effects of medications
Stress, anxiety and depression
Eating disorders
Pregnancy
Bowel conditions such as diverticular disease, irritable bowel syndrome and bowel cancer[5]
One of the more serious consequences of long-term chronic constipation is faecal impaction leading to a build-up of hard stools in the rectum, which may need to be managed in hospital with treatment such as enemas, suppositories or manual disimpaction.[5,6] Chronic constipation and straining can also lead to haemorrhoids (piles) causing bleeding from the anus that may require surgical treatment.[5,6,10,11]
Diet and supplements for constipation
The new guidance contains 59 recommendations about the treatment of chronic constipation.[1] In the past it was recommended that patients with chronic constipation follow a general high fibre diet approach such as wholemeal bread and cereals, more fruit and vegetables, bran, etc, or take over-the-counter laxatives. However, the new guidance states that there is no strong clinical evidence to back this approach.[1,2]
The new guidelines are based on four systematic reviews and meta-analyses of randomised controlled trials. Although some of the evidence is classed as low-level, the following recommendations are made:
Trial specific fibre supplements such as psyllium and inulin at doses above 10g/day for a minimum duration of four weeks, increased slowly with sufficient fluid intake. May cause side effects such as bloating and flatulence.
Prunes are as effective in relieving constipation as psyllium.
Trial a probiotic. There is not enough clinical evidence to recommend any particular strains so the guidance suggests that patients trial a probiotic of their choice for a least four weeks, following the manufacturer’s dose instructions.
There is not yet enough evidence to routinely recommend synbiotic supplements (this is a combination of prebiotics and probiotics).
Trial magnesium oxide supplements at a dose of 0.5–1.5g/d for at least four weeks.
Consuming two or three kiwi fruit a day for at least four weeks (including the skin) will provide additional fibre that may be beneficial. However, this may also potentially increase side effects of bloating.
Drinking 500–1500ml/day of high mineral-content water for two to six weeks may improve symptoms. Note that there is a lack of evidence for simply increasing general fluid intake by itself.
Other areas that need further research before specific recommendations can be made include: caffeine, fermented products such as kefir, vitamin C and senna medication.
There is little evidence that ‘trigger’ foods such as rice and bananas can cause constipation.[1,2]
Increasing fibre intake and food wastage – the Root To Tip project
The statistics around food wastage are shocking. One third of all food globally is wasted and the UK throws away 9.5 million tonnes a food every year.[12-15] This equates to 70kg of food per person or 140 meals, wasted every year.[14] The amount of food wasted could feed up to 30 million people, yet around 8.4 million people live in food poverty in the UK.[14] The top five most wasted foods are:
Bread
Milk
Potatoes
Bananas
Salad vegetables[14]
The government has set a target of reducing food waste by 50% by 2030.[13,15] One of the ways (among many others) that we can reduce food waste is to use more of the fruit and vegetables in cooking. King’s College London launched a Root to Tip project this year, which aims to produce recipes using parts of the plant that are normally discarded such as:
Stalks
Peel/skins
Leaf tips
Roots[16]
The project will move to offering Root To Tip meals for King’s College staff and students and to analyse the feedback. Some of the ways they suggest we use the fruit and vegetables parts in cooking include:
Roasting root vegetable skins or leaves
Using beet tops for pesto or carrot greens for chimichurri sauce
Making jams or preserves from fruit rinds
Adding vegetable stems to soups, stews or stir-fries[12,16]
The project leads hope to support behaviour change in consumers by encouraging plant-based eating and giving caterers and food manufacturers the tools to deliver these meals.[12] The hope is to increase intake of fibre and vitamins and minerals, reduce food wastage, reduce consumption of animal products and improve sustainability.[12] The plant-based menu being trialled at King’s College London sounds extremely tasty, including dishes such as kale, fennel and toasted seed salad, orzotto with seasonal vegetables, cauliflower cheese and beetroot, cottage cheese and walnut pasta.[12,16]
Conclusion
Chronic constipation is a common and problematic condition that has a significant impact on health and wellbeing. The publication of the BDA’s Guidelines for the Dietary Management of Chronic Constipation in Adults provides us with clear evidence-based guidance on how to treat this condition with advice on diet changes, fluid intake and use of supplements. Innovative projects such as Root To Tip improve awareness of the practicalities of using whole fruits and vegetables in cooking and making plant-based meals, as well as the health benefits. Hopefully, in the near future we can reduce food wastage and improve food sustainability with more industry and consumer uptake of plant-based meals.
Katy is currently a Specialist Renal Dietitian working in the community. She has 20 years of experience working in the NHS in various roles, including
nutrition support, ICU and renal.
Katy Stuart, RD, Specialist Renal Dietitian
References:
British Dietetics Association [Internet] The BDA’s first evidence-based dietary guidelines for chronic constipation are now available. Accessed Oct 2025 Available from: https://www.bda.uk.com/resource/the-bda-s-first-evidence-based-dietary-guidelines-for-chronic-constipation-are-now-available.html
Dimidu E, van der Schoot A, Barret, K et al. British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults. Journal of Human Nutrition and Dietetics. 2025 https://onlinelibrary.wiley.com/doi/10.1111/jhn.70133
Kings College, London [Internet] Eating 'Root-to-Tip': Increasing fibre intake, reducing food waste. 2025 https://www.kcl.ac.uk/eating-root-to-tip-increasing-fibre-intake-reducing-food-waste
Kings College London [Internet] Maximum nutrition, minimum waste: ‘Root-to-Tip’ dining. 2025 https://www.kcl.ac.uk/research/maximum-nutrition-minimum-waste-root-to-tip-dining
NHS, Constipation [Internet] 2025 https://www.nhs.uk/conditions/constipation/
National Institute for Health and Care Excellence, Constipation in Adults 2025 https://cks.nice.org.uk/topics/constipation/management/adults/
Serra J, Pohl D, Azpiroz F et al. Functional Constipation Guidelines Working Group. European Society of neurogastroenterology and motility guidelines on functional constipation in adults. 2019 Feb;32(2) Neurogastroenterology and Motility https://pubmed.ncbi.nlm.nih.gov/31756783/
Barberio B, Judge C, Savarino E, Ford A. Affiliation Global prevalence of functional constipation according to the Rome criteria: a systematic review and meta-analysis. Lancet Gastroenterology Hepatology 2021 Aug;6(8):638-648 https://pubmed.ncbi.nlm.nih.gov/34090581/
Belsey, J, Greenfield, S, Geraint, M. Systematic review: impact of constipation on quality of life in adults and children Alimentary Pharmacology & Therapeutics May;31(9):938-49 https://pubmed.ncbi.nlm.nih.gov/20180788/
Cancer Research UK [Internet] Faecal Impaction, 2025 https://www.cancerresearchuk.org/about-cancer/coping/physically/bowel-problems/types/chronic-constipation
NHS, Haemorrhoids [Internet] 2025 https://www.nhs.uk/conditions/piles-haemorrhoids/
Lambeth Climate Partnership [Internet] 2025, Maximum nutrition, minimum waste: ‘Root-to-Tip’ dining at King’s College London https://lambethclimatepartnership.org/live-project/maximum-nutrition-minimum-waste
British Dietetics Association, Maximum nutrition, minimum waste by Dr Rachel Gibson Sep 2025 https://www.bda.uk.com/resource/maximum-nutrition-minimum-waste.html
Waste Managed [Internet] Food Waste – 2025 Facts & Statistics https://www.wastemanaged.co.uk/our-news/food-waste/food-waste-facts-statistics/
The Waste and Resources Action Programme [Internet] 2025 UK Food Waste & Food Surplus – Key Facts https://www.wrap.ngo/resources/report/uk-food-waste-food-surplus-key-facts
Kings College Hospitality Menu [Internet] 2025 https://www.kcl.ac.uk/assets/kingsvenues/KFHospFood-010425-v2.1.pdf
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