What is a low FODMAP diet?

What are FODMAPS?

FODMAPs are Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. The acronym groups together specific types of short-chain carbohydrates that are either slowly absorbed or remain undigested in the small intestine.

Why do people choose to follow a Low FODMAP diet?

The aim of the diet is to help patients identify food triggers so that they can control their problematic symptoms. This is done through an initial dietary reduction of all FODMAPs, followed by strategic re-introduction; the patient will end up with a personalised diet suited to them.

Because of their small molecular size, they increase water content in the small intestine through osmotic effect, and because they are readily fermented by bacteria, their delivery to the large bowel results in gas production.

FODMAPs can therefore distend the bowel.

In patients with IBS who are hypersensitive to this stretching, symptoms can occur such as abdominal pain, bloating, excess flatulence and changes in bowel habit. (World Gastroenterology Organisation, 2018).

What foods are to be avoided on a low FODMAP diet?

The low FODMAP diet includes reducing dietary intake of the five main subgroups of carbohydrates: (World Gastroenterology Organisation, 2018).

Low FODMAP Categories

Carbohydrate subgroup	Example
Fructose in excess of glucose	Honey, mango
Lactose (when hypolactasia is present)	Milk, yoghurt
Sugar polyols (including sorbitol and mannitol)	Avocado, mushrooms
Fructans	Wheat, onion, garlic
Galacto-oligosaccharides (GOS)	Legumes, soy milk

Is following a low FODMAP diet dangerous?

The diet itself is very complex and should only be attempted under the supervision of a dietician.

If a low FODMAP diet is followed but the patient does not then reintroduce FODMAPS into their diet, it can have detrimental effects. There is the potential that restricting FODMAPs including prebiotic fructans and galacto-oligosaccharides, could have marked effects on the composition of the microbiota. Studies also show that total energy, carbohydrate and calcium intake may be reduced. 

It is true that reducing the intake of highly fermentable fibres, as part of a low FODMAP dietary approach (see section 3), is recommended for the management of IBS and provides symptomatic relief in approximately 75% of patients (World Gastroenterology Organisation, 2018). However, this should not be attempted without the supervision of a medical professional.

Conclusion
To conclude a low FODMAP diet restricts the consumption of certain short-chain carbohydrates. It is recommended as a treatment for those with IBS as it can help control bloating and distention. However, it should never be attempted without advice from a medical professional.