Dietary Fibre

Low fibre comes from eating few whole plant foods. Too much fibre, or a sudden increase, can cause gas, bloating and cramps because bacteria ferment it. Some conditions change how much or what type of fibre suits you: for example, a narrowed bowel (stricture), a recent flare of inflammatory bowel disease, bowel surgery or blockage may require a lower-fibre diet, while constipation, diverticular disease prevention and high cholesterol often benefit from more.

Many adults in modern diets eat less fibre than recommended, because of more refined grains, fewer vegetables and legumes, and more processed foods. Low fibre intake is a common contributor to constipation and is linked with other long-term health problems.

Local foods that offer fibre include whole wheat bread, bulgur, freekeh, barley, lentils, foul (fava beans), chickpeas, dates and vegetable stews. During Ramadan, drink enough fluids between iftar and suhoor and include fibre in both meals to help prevent constipation.

There is no test for low fibre intake. A doctor or dietitian reviews what you eat (sometimes with a food diary), your bowel habits and your medical history. Tests such as blood tests, stool tests or colonoscopy are done to rule out other causes when you have warning signs or persistent changes. If you have a medical condition that affects how much fibre you can take, your specialist gives personal advice.

Fibre works best together with fluids and activity, and when it is increased slowly.

• Increase fibre gradually over a few weeks to let your gut adapt.

• Drink enough fluids through the day; fibre without fluids can make constipation worse.

• Be active every day; walking helps the bowel to move.

• Do not ignore the urge to pass stool, and set aside unhurried toilet time, for example after a meal.

• Keep a food and symptom diary if you notice that certain high-fibre foods upset you.

Aim to get fibre from a variety of foods. Adults are generally advised to eat roughly 25 to 30 grams a day; your doctor or dietitian can give a target that suits you.

• Choose whole grains: oats, brown rice, whole wheat bread, barley, bulgur, freekeh.

• Eat vegetables and fruit daily, with edible skins where suitable.

• Add legumes such as lentils, chickpeas and beans a few times a week, starting with small portions.

• Snack on nuts, seeds and dried fruit such as dates and figs, in moderate amounts.

• If you have a bowel narrowing, recent bowel surgery, or an active inflammatory bowel disease flare, follow your specialist advice about lowering fibre, such as peeling, cooking well or choosing softer foods.

If food alone is not enough, fibre supplements are available. Ask your doctor or pharmacist which suits you and the amount to take.

• Psyllium (ispaghula) is a soluble fibre supplement used for constipation and sometimes for loose stools; take it with plenty of water.

• Start with a small amount and build up slowly to avoid gas and bloating.

• Take supplements separately from other medicines, as fibre can reduce absorption of some of them; ask your pharmacist about timing.

• Avoid fibre supplements if you have a bowel blockage, difficulty swallowing or unexplained severe constipation until you have been assessed.

Fibre itself does not need a procedure. Tests are used when symptoms do not respond or warning signs appear.

• Colonoscopy may be advised for rectal bleeding, a persistent change in bowel habit, anaemia, weight loss, or as part of age-based bowel cancer screening.

• Tests of bowel movement (such as anorectal tests) may be used for stubborn constipation.

Studies consistently link diets rich in fibre, especially from whole grains, vegetables, fruits and legumes, with better bowel function and with lower risks of heart disease, type 2 diabetes and bowel cancer. Different fibres act differently: psyllium helps both constipation and loose stools, while some fermentable fibres can worsen symptoms in irritable bowel syndrome. A gradual, food-first approach is advised.

For most people, steadily raising fibre and fluids improves stool regularity within a few weeks, and benefits continue as long as the habit continues. Where symptoms persist despite good fibre intake, other causes should be looked for.

• How much fibre is right for me with my condition?

• Should I use a fibre supplement, and which one?

• Does fibre interact with my medicines?

• Which fibre-rich foods should I avoid during a flare or after surgery?

• Do I need tests if my constipation continues?

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.