Irritable Bowel Syndrome (IBS) and Diet

Irritable Bowel Syndrome (IBS) is a common condition presenting with a range of symptoms that varies from person to person in its manifestations and severity.

Symptoms of IBS

Common symptoms are:

• Flatulence and/or bloating
• Diarrhoea or constipation or both
• Lower abdominal pain that may reduce after a motion
• Passage of mucous
• Feeling the need to evacuate even after completing it
• Urgency to ease bowels
• Worsening symptoms after meals

Reducing IBS symptoms

For reducing the symptoms patients have to ensure that meals are taken regularly, slowly and at proper time along with regular physical activity/exercises and adequate relaxation.

An association between the type of food and development of symptoms can be made using a diary. Dietary changes should be made carefully allowing the bowel to adjust.

IBS and diet

Fruits and vegetables contain varying amounts of soluble (pectin, hemicellulose) and insoluble (cellulose, lignin) non-starch polysaccharides termed widely as “fibres”. Cereals on the other hand mainly contain insoluble fibre. Though an increased fibre intake is often the recommendation in IBS, the cereal fibres are found to exaggerate the symptoms in 55% cases.

The soluble fibre variants include psyllium, methylcellulose and ispaghula which are less detrimental and thus can be used for fibre supplementation in IBS.

Dietary adjustments for IBS patients

Dietary adjustments for patients with wind and bloating include limiting fruits to 3 portions (with 1 portion of dried fruits if desired), fruit juice to a small glass and “5 a day” with vegetables.

Oats and golden linseeds are also found to be helpful. Resistant starches that are not completely digested and enter the large bowel to get fermented and produce gas should be restricted.

Diarrhea predominant IBS

If diarrhoea occurs adequate fluids should be taken to replace the losses, limiting consumption of fizzy drinks, alcohol and caffeinated drinks. Fruits, vegetables and resistant starches should be according to prescribed limitations. Sugar free sweets and products containing sorbitol are better avoided. Higher fat intake might also be responsible for diarrhoea and thus should be restricted.

Persons willing to try probiotic yoghurts or fermented milk drinks should consume them at manufacturer recommended amounts over a period of time to attain their benefits. A change of brand might also help in absence of a response as the bacterial content varies.

Constipation predominant IBS

If constipation is the worrying symptom dietary fibre intake should be enhanced. However these tend to generate gas that might worsen symptoms and thus should be gradually increased and adjusted according to its effects.

An adequate fluid intake is essential and probiotics might be helpful. Addition of oats and golden linseeds acts as a soluble fibre softening stool.

1 portion fruit or vegetables	Example
Fresh fruits (80gms)	1 apple, banana, pear, orange or similar sized fruit, ½ grapefruit, 1 slice of large fruit (melon, pineapple) 2 plums a handful of grapes, cherries, berries 3 heaped tablespoons fruit salad
Dried fruits (25gms)	1 heaped tablespoon raisins, figs, apricots
Vegetables (80gms)	3 heaped tablespoons raw, cooked, frozen or tinned vegetables a dessert bowl of salad

Food allergies and IBS

Food allergy is often held responsible by affected persons as the symptoms are related to meals. Though true allergies are difficult to prove, food intolerance might be present. In patients with atopy, IgE mediated allergy might be more common.

The definite way to exclude food intolerance is by a food challenge. Refractory cases can be treated with a dietary exclusion keeping in mind to not restrict it severely to affect nutrition. This approach is best supervised by a dietician.

Another topic of investigation is carbohydrate (lactose, fructose and sorbitol) intolerance as an etiology of IBS. The presence of food intolerance has geographical variations and racial heterogenity. However, its incidence in patients suffering from IBS does not differ much from general population.

On the contrary fat intolerance is found to be greater in patients with IBS as lipids can generate greater hypersensitivity. Thus a prudent adjustment of fibre, carbohydrate and fat helps in the management of symptoms instead of a severe restriction or dietary exclusion.

Further Reading

• All Irritable Bowel Syndrome Content
• What is Irritable Bowel Syndrome (IBS)?
• Irritable Bowel Syndrome (IBS) Symptoms
• Irritable Bowel Syndrome (IBS) Causes
• Irritable Bowel Syndrome (IBS) Diagnosis

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.