Fibre and constipation: two reviews, two different results
A 2025 review of seven trials in older adults found no significant gain in stool frequency, but significantly less use of laxatives or enemas.
The NHS lists gradually eating more fibre among the simple diet and lifestyle changes that can help treat constipation, but two reviews of clinical trials, published in 2012 and 2025, found different things.
Constipation is common and affects people of all ages, the NHS says; it is more common over 65. Signs include fewer than three stools in a week, hard, dry or lumpy stools, and straining or pain.
The NHS fibre page says government guidelines put intake at 30g a day, while most adults eat an average of about 20g. It suggests pulses such as beans, lentils or chickpeas.
Self-help steps on the NHS constipation page include:
- a healthy balanced diet, including fruits that contain sorbitol such as apples, apricots, grapes and raisins, raspberries and strawberries
- plenty of water and other fluids, and avoiding alcohol
- gradually more fibre, including wheat bran, oats or linseed
- a regular time and place for the toilet, without delaying when the urge comes
- feet resting on a low stool, knees above the hips if possible
- a daily walk or run
The 2012 and 2025 reviews
A 2012 review in the World Journal of Gastroenterology pooled five randomised trials that compared fibre with a placebo. People taking fibre had stools more often, but there was no significant difference in stool consistency, treatment success, laxative use or painful bowel movements.
A 2025 review in the journal Foods looked at seven trials with 187 older adults who had chronic constipation. It found no significant improvement in how often they passed stools with fibre supplements, but fibre significantly reduced how often laxatives or enemas were used. The authors wrote that fibre may reduce reliance on laxatives and called for more trials to find the most effective dose and length of use.
The 2012 review found a gain in stool frequency but no significant change in laxative use; the 2025 review found the reverse, in older adults only.
When to see a pharmacist or GP
The NHS says to speak to a pharmacist if diet and lifestyle changes are not helping. A pharmacist can suggest a laxative, most of which work within three days, and the NHS says they should only be used for a short time.
The NHS also says constipation can be caused by a medical condition such as diverticular disease or bowel cancer, but that this is rare. It says to see a GP if someone:
- is constipated and it is not getting better with treatment
- is regularly constipated
- is regularly bloated
- has blood in the stool
- has lost weight without trying
- is constipated and feels tired all the time
- takes a medicine that is causing constipation, such as opioid painkillers
- notices sudden changes in bowel habits
- has tummy pain
The NHS adds that people should speak to the GP before they stop taking any prescribed medicine.
