What is the low-fibre diet?

How does the low-fibre diet work?

If you are experiencing symptoms that suggest you have an irritated or inflamed bowel, you may be advised to adopt a low-fibre diet. This involves avoiding foods that are considered fibrous. The theory behind this is that by minimising your intake of these foods, your digestive system has an opportunity to rest. It will also reduce the amount of stool produced, and this may ease the discomfort you're experiencing. As minimal 'residue' is left in the bowel, it is sometimes called a low-residue diet.

Conditions that may benefit from this approach include:

• Persistent diarrhoea, especially if caused by a flare-up of irritable bowel syndrome (IBS)
• Crohn’s disease or diverticulitis
• Those with or at risk of a bowel obstruction because of a stricture (narrowing)
• Cases where excess gas is produced
• Those preparing the bowel for medical investigations

What foods can I eat on a low-fibre diet?

A low-fibre diet is made up of foods that are easily digested and absorbed, leaving minimal residue in the bowel. Examples of foods to include are:

• Fruits and vegetables: such as sieved tomato sauces (no skin or seeds), tomato purée, well-cooked vegetables (with no skin, seeds, or stalks), mash or creamed potatoes (no skin), melon (no seeds/skin), stewed apple, plums, canned pears/peaches, ripe bananas, avocado and fruit juices with no pulp
• Starchy carbohydrates: any white bread, white rice and pasta, plain scones, white pitta, chapati and refined breakfast cereals like cornflakes and puffed rice
• Meat, fish, dairy and alternatives: all fresh meat, sausage and bacon (avoid tough or fatty meat). All fresh, frozen, smoked fish and fish in white breadcrumbs/batter. Eggs, soya and tofu. All milk, yogurt (with no. added bits) and cheese
• Sugary foods: ice cream, jelly, custard, plain biscuits, jelly-type jams, marmalade (no peel), lemon curd, chocolate and sweets – don't forget these should be consumed in moderation, in line with dietary guidelines
• Sauces: tomato sauce, brown sauce, salad cream and mayonnaise, yeast extract, gravy and white sauce
• Liquids: smooth and creamed soups like chicken soup. Tea, coffee, squash and smooth milkshakes

What foods should I avoid on the low-fibre diet?

• All fruit skins, stalks, seeds and stones; all dried fruit and smoothies
• All vegetable stalks, skins, seeds and peel. Raw vegetables and all other vegetables not listed above, including cabbage, curly kale, sweetcorn and celery. You should also avoid composite dishes such as coleslaw
• Wholemeal, granary and rye bread. All fruit and nut breads, including walnut, granary or fruit muffins or scones and pastries with fruit/dried fruit
• Brown rice, wholemeal pasta and bulgur wheat
• Wholegrain and high-fibre cereals, such as wheat breakfast biscuits, bran-based cereals, porridge oats, muesli and wheat germ
• Meat casseroles, pies, pasties containing vegetables
• Fish in wholemeal breadcrumbs and canned fish with bones, such as sardines
• All types of nuts and all peas, beans, pulses (e.g. kidney and baked beans), as well as lentils
• Hummus
• Yogurt with 'bits'
• Jam and marmalade containing fruit, seeds or peel
• Nut butters, unless smooth
• Cake, scones or chocolate containing dried fruit
• Pickles
• Canned sauces containing vegetables or fruit
• Packet or canned soup with vegetables added
• Herbs and spices
• Milkshake syrups with real fruit and seeds
• Popcorn
• All seeds

What's the difference between a low-fibre and low-residue diet?

While fibre is a component we get from our diets, the term 'residue' refers to anything that's left in the large intestine after digestion. This could include undigested food, gas, bacteria, cells and secretions from the gut lining. Low-residue and low-fibre diets are similar, which is why the terms are often used interchangeably, because they both share the same objective: limiting bowel activity and easing digestive discomfort, including cramping and diarrhoea.

Is the low-fibre diet healthy?

With a lengthy list of foods to avoid, the low-fibre diet is highly restrictive, and as a result limits the nutrients you're able to get from your diet. This could lead to further symptoms and complications over time. For this reason, the diet should only be followed on the advice and supervision of your GP or health professional, such as a registered dietitian or nutritionist. It's also important to note that this diet is not recommended for weight loss.

What's the evidence for the low-fibre diet?

The value of a low-fibre diet is in its ability to empty the digestive tract for diagnostic investigation or rest the gut for therapeutic purposes; for example, after a flare up of a bowel condition like Crohn's. Adopting the diet to prepare for a colonoscopy or similar procedure appears to be well tolerated, with better compliance and satisfaction than a liquid diet.

In addition to this, a low-fibre diet appears to help different bowel disorders, including diverticulitis; once a period of remission has been achieved, sufferers may be able to gradually increase the amount of fibre in their diet. This does depend on the diagnosed condition however, and more studies are needed in this area. Findings to date, though, suggest constipation and gut symptoms may improve once fibre is re-introduced to guideline levels.

A nutritionist's view

A low-fibre diet does go against what we understand a healthy, balanced diet to be, so it's no wonder its use is restricted for specific purposes only. These include preparing the bowel for a diagnostic or investigative procedure and for alleviating acute relapse in those with bowel disease. If you are advised to adopt this diet by a medical professional and are doing so for more than a few weeks, you may need to supplement with a broad-spectrum multi-vitamin and mineral, especially if you are unable to eat a variety of fruit and vegetables.

Once your condition is under control or you've completed any investigative procedures, you should speak to your medical practitioner about safely re-introducing some fibre to your diet.

Due to the highly restrictive nature of a low-fibre diet, it should only be used on the advice of a dietitian or doctor, and should not be allowed for the long-term. If you are curious about low-fibre diets, speak to your GP or a registered dietitian who can advise accordingly.

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Tai Ibitoye is a registered dietitian and a doctoral researcher in food & nutritional sciences. Tai has experience working in different sectors such as in the NHS, public health, non-government organisations and academia.

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