A guide to FODMAPs & IBS

What are FODMAPs? 

FODMAPs stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. They are short-chain carbohydrates that are resistant to digestion in some people.

Research has found that FODMAPs can trigger symptoms of medically diagnosed Irritable Bowel Syndrome (IBS) and following a low FODMAP diet can help relieve symptoms of IBS.

The 4 types of FODMAPs

1. Oligosaccharides

Oligosaccharides include both fructans and galacto-oligosaccharides (GOS). It is important to remember that everyone absorbs these poorly. Some people are just able to better tolerate them than others.

Fructans mostly come from wheat products and some vegetables, such as onion and garlic. 

This group of FODMAPs also includes inulin (a type of fibre), which is often added to yoghurt, and fructo-oligosaccharides, which are found in packaged foods.

GOS are found in legumes. The technical names are raffinose and stachyose.

Garlic contains fructans (oligosaccharides) and should be excluded in the the first stage of the low FODMAP diet.

2. Disaccharides

Lactose is a disaccharide that naturally occurs in milk and milk products. All of us vary in the amount of lactose we can digest. As we age, we have less of the enzyme lactase, that breaks down lactose.

Some ethnic backgrounds (such as those of Asian descent) naturally have less lactase and tend to be more likely to have lactose intolerance.

3. Monosaccharides

Fructose is a monosaccharide, which is most commonly in fruit. It’s usually only a problem for people with medically diagnosed IBS if the food contains more fructose than glucose, or with excess consumption in a single sitting.

4. Polyols

Polyols include sorbitol and mannitol. These are naturally occurring in some fruits and vegetables, while maltitol, xylitol, isomalt and polydextrose are used to artificially sweeten food and as food additives.

Everyone only partially absorbs polyols.  Some polyols may appear in the ingredients list under their additive number: 

• Sorbitol (420)
• Mannitol (421)
• Maltitol (965)
• Xylitol (967)
• Isomalt (953) (contains sorbitol and mannitol)
• Polydextrose (1200) (10% sorbitol)

Knowing your IBS triggers may help better manage the condition for the long-term and help improve your quality of life.

What is medically diagnosed IBS?

Medically diagnosed IBS is a functional gastrointestinal disorder characterised by symptoms such as cramping, abdominal pain, bloating, gas, diarrhoea or constipation, or both.

The symptoms of IBS can be on either and both ends of the bowel movement spectrum. Further complicating this chronic condition is that there is currently no known cause or cure.

But don’t be disheartened, determining your IBS triggers may help better manage the condition for the long-term and help improve your quality of life.

What causes medically diagnosed IBS?

While the cause of IBS is unknown, factors such as stress, change in routine, infection and diet, can trigger an attack.

FODMAPs and IBS

As FODMAPs travel through the gastrointestinal tract, they can be poorly absorbed in the small intestine drawing excess fluid into the gut.

This can result in diarrhoea for some people. For others, the carbohydrates can move into the large intestine where they undergo fermentation by bacteria, producing gas. This gas can lead to symptoms including bloating, constipation, flatulence, pain and nausea.

Low FODMAP diet 

Research has found that following a low FODMAP diet may help reduce symptoms of medically diagnosed IBS in some people. 

However, it’s important to determine which part of the acronym affects you, as strictly eliminating all FODMAPs can have adverse impacts on your long-term health.

If in doubt, consult your health professional for more advice. 

The low FODMAP diet occurs in three phases.

Stage 1: The elimination phase occurs over four weeks, eliminating your intake of high FODMAP foods.

Stage 2: The FODMAP reintroduction phase will reintroduce each FODMAP back into your diet, one at a time, observing your tolerance and whether they trigger your IBS symptoms.

Stage 3: Once you have determined which FODMAPs trigger your IBS, you can tailor your eating habits to avoid only the necessary foods.

Reviewed by the Healthylife Advisory Board November 2021