Home / Patient guides / Fibremaxxing
Fibremaxxing: a bowel surgeon's view
Fibremaxxing, the social media trend of deliberately eating as much fibre as possible, is mostly a good idea: 96% of people in the UK eat less than the recommended 30 g a day, and fibre helps constipation, piles, diverticular disease and probably bowel cancer risk. But increase it gradually, drink more water, and take care if you have IBS, Crohn's with narrowing, or an ileostomy.
What fibre does
- Soluble fibre (oats, beans, lentils, fruit, psyllium) forms a gel, softening stool and feeding gut bacteria.
- Insoluble fibre (wholegrains, bran, skins and seeds) adds bulk and speeds transit.
- Gut bacteria ferment fibre into short-chain fatty acids, which nourish the lining of the colon. This is one reason higher-fibre diets are linked to a lower bowel cancer risk.
Where more fibre clearly helps
| Condition | Effect of fibre |
|---|---|
| Constipation | Softer, bulkier stools; less straining |
| Piles and anal fissure | Less straining reduces bleeding and pain and helps fissures heal. See piles guide. |
| Diverticular disease | Associated with fewer symptoms and attacks. Seeds and nuts do not need to be avoided. |
| Bowel cancer risk | Higher intake is associated with lower risk |
Where fibremaxxing can backfire
- IBS: a sudden increase, especially in bran and fermentable foods, often worsens bloating and pain. Soluble fibre such as psyllium or oats is usually better tolerated. A dietitian-led low-FODMAP approach helps some people.
- Crohn's disease with a narrowing: bulky, stringy fibre can cause blockage. Follow your IBD team's advice.
- Ileostomy or after bowel surgery: fibrous foods can block a stoma. Chew well and reintroduce slowly.
- Not drinking enough: extra fibre without fluid can make constipation worse.
How to increase fibre without bloating
- Add around 5 g a day each week rather than overhauling your diet overnight.
- Drink an extra glass or two of water a day.
- Spread fibre across meals.
- Favour variety: oats, beans, lentils, wholegrains, vegetables, fruit with skins, nuts and seeds.
- If bloating persists after a few weeks, ease back and favour soluble fibre.
Diet will not fix a new symptom
If bleeding, a change in bowel habit, weight loss or abdominal pain starts or persists, get it checked rather than adjusting your diet and waiting. See bowel cancer under 50.
Common questions
How much fibre should I eat a day?
UK guidance is 30 g a day for adults. Most people eat considerably less, so for most the advice is to increase gradually.
Can too much fibre be bad for you?
A sudden large increase can cause bloating, wind and cramps, especially with IBS. Very high fibre can also cause problems with Crohn's narrowing or an ileostomy.
Does fibre help piles?
Yes. Softer stools reduce straining, which reduces bleeding and helps prevent piles getting worse.
Should I avoid seeds and nuts with diverticular disease?
No. That old advice is not supported by evidence. A high-fibre diet including nuts and seeds is fine for most people.
This guide is general information, not personal medical advice. If you have severe abdominal pain, heavy bleeding, a high temperature or vomiting, call 111, or 999 in an emergency.