Using nutrition to manage your irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) is a functional bowel disorder that affects between 7 and 15% of the world’s population, with women being more frequently affected than men. Although relatively common, it often goes undiagnosed, which can lead to a reduced quality of life for the individual.

Its cause is unknown, but possible hypotheses include increased sensitivity of the nerves lining the intestines, impaired gastrointestinal motility, alterations in the gut microbiota, and low-grade inflammation.

The main symptoms of IBS are diarrhea or constipation or both, abdominal pain, bloating and abdominal distention and excessive wind passage.

Diagnostic

There is no test to diagnose IBS, with symptoms playing a major role in diagnosis. According to the Rome IV criteria, IBS can be diagnosed if the individual reports recurrent abdominal pain on average at least one day per week for the previous three months, associated with at least two of the following:

• related to passing stools;

• associated with a change in stool frequency;

• associated with a change in stool consistency;

• Symptoms must have started at least six months previously.

It is crucial that before the diagnosis of IBS, other organic diseases such as inflammatory bowel disease, endometriosis and celiac disease are excluded. Red flags that are not typical of IBS and warrant further investigation include unexplained weight loss, rectal bleeding, recurrent vomiting, and nocturnal bowel movements.

Treatment options

The therapeutic strategies to be used in IBS can and should be different for different individuals, with the choice of treatment generally being guided by the predominant symptoms. Types of treatment include drug therapy (such as antidiarrheals, antispasmodics, or laxatives), dietary therapy (such as a low-FODMAP diet), exercise, supplements (such as probiotics), and psychological therapies (such as stress management and gut-directed hypnotherapy).

The low-FODMAP diet

Among dietary therapies for IBS, the low FODMAP diet (created by researchers at Australia’s Monash University) has emerged as the most promising option, with studies typically reporting that around 75% of patients with IBS SII experience significant improvement from this diet.

“FODMAP” is an acronym that stands for Fermentable Oligo-Di-Mono-saccharides And Polyols. FODMAPs are a group of short-chain carbohydrates that tend to be poorly absorbed in the small intestine, drawing water into the intestine by osmosis.

When they reach the large intestine, they are quickly fermented by bacteria, generating gas. These two actions lead to an increase in the volume of the intestinal contents, stretch the intestinal walls and stimulate the nerves of the intestine. This leads to the sensation of pain in IBS sufferers, who are thought to (i) be more likely to malabsorb FODMAPs and (ii) have increased gut sensitivity.

Additionally, stretching of the intestines and excessive fermentation can also cause distention, diarrhea, or constipation.

There are six main classes of FODMAPs:

• Lactose, present in dairy products such as milk, yoghurt and ice cream;

• Fructans, found in fruits like grapefruit, vegetables like onions and garlic, and grains like wheat and barley;

• Galacto-oligosaccharides, present mainly in legumes, cashew nuts and pistachios;

• Sorbitol, present in fruits such as apples and in sugar-free chewing gum;

• Mannitol, present in vegetables such as mushrooms and cauliflower; and

• Fructose in excess of glucose, present in fruits such as pears, vegetables such as asparagus and in honey.

Implementation of the low FODMAP diet

The low FODMAP diet is a relatively complicated exclusion diet that should only be followed under the strict supervision of an experienced dietitian.

It is implemented in three stages:

In the first stage, all foods high in all FODMAPs are excluded. This stage lasts about two to six weeks and the goal is to achieve symptom relief.

In a second step, the different classes of FODMAPs are reintroduced (“challenged”) in a specific way (different depending on the person), with the aim of knowing which FODMAPs the person tolerates and at what doses. This stage lasts about two months.

In the third step, the information obtained in step 2 is used by the dietitian to construct a personalized diet for the individual, with the aim of relaxing restrictions and broadening the diet while maintaining symptom control at long term.

Examples of low FODMAP diet swaps:

• instead of apples, peaches and

watermelon, choose oranges, kiwi and melon;

• instead of garlic, onions and cauliflower, opt for zucchini, potato and carrot;

• instead of wheat bread and couscous, opt for gluten-free bread and quinoa;

• instead of cashews and pistachios, choose peanuts and pine nuts;

• instead of normal cow’s milk, choose lactose-free milk.

Manuel Attard is a Registered Dietitian trained by FODMAP (Monash University).

www.manuelattard.com