What are FODMAPs and How Can They Cause IBS?


The term “FODMAP” sounds like a made-up name for a sci-fi character. Truth is, it’s an acronym created by an amazing Aussie team of researchers at Monash University, used to describe a group of fermentable short chain carbohydrates that may, when consumed in excess, be the cause of unpleasant gastrointestinal (GI) symptoms.

What are FODMAPS?

Let’s break it down. The acronym stands for:

F – Fermentable: The process in which gut bacteria degrades undigested carbohydrate to produce gases (hydrogen, methane and carbon dioxide)

O – Oligo-saccharides: There are two main types of oligo-saccharides: fructose-oligosaccharides (FOS), found in foods such as onions, garlic, wheat and rye, and galacto-oligosaccharides (GOS), found in legumes and pulses. As humans, we malabsorb (i.e., can’t break down) either of these.

D – Disaccharides: This includes lactose found in dairy products (milk, yoghurt, ice cream, cheese, custard, cream etc.). Lactase is the enzyme responsible for digesting lactose. If you don’t have enough lactase enzymes, your body is unable to separate the two sugar units that make up lactose, and you will (you guessed it!) malabsorb it, causing unpleasant GI symptoms (like wind, bloating, frequent loo trips … or no trips at all!)

M – Mono-saccharides: Fructose is the main mon-saccharide, and up to half of all adults malabsorb excess fructose. Glucose, another sugar, co-transports fructose across intestinal cells to enter the body. When you consume more fructose than glucose, your body can’t process the fructose in time and you may malabsorb it. Some examples of foods that contain excess fructose include honey, apples, and stone fruit. The good news is that foods with equal glucose to fructose ratios are easily absorbed and generally don’t trigger IBS symptoms in low FODMAPers.

A – And (the easiest FODMAP to remember and not really a FODMAP at all!)

P – Polyols: Polyols are sugar alcohols found naturally in some fruit and veg, as well as artificial sweeteners (e.g., mannitol, sorbitol, isomalt and xylitol). As they are incompletely absorbed across the small intestine, they are often the culprit of undesirable GI symptoms. The tricky thing about Polyols is that they are hidden in many packaged foods, which is why getting cluey on reading labels is a big must-do while following the low FODMAP diet.

How do FODMAPs Influence IBS?

So, in summary, FODMAPs are a group of dietary sugars (short chain carbohydrates) that, in IBS sufferers, can send us on a one-way ticket to the loo. The process starts when the small intestine fails to absorb these carbohydrates. The presence of FODMAPs in the small intestines causes water to be dragged in, potentially leading to diarrhoea.

The malabsorbed sugars then make their way to our large intestine where they become food for our gut bacteria, which use the FODMAPs to create energy. None of

this sounds too bad, except as the gut bacteria feast they rapidly ferment the short chain carbohydrates. This creates large quantities of hydrogen and methane (bad smelling) gases, which leads to flatulence and constipation … not exactly desirable! As if that weren’t bad enough, the combination of water retention and gas production causes our intestines to expand, making us feel incredibly bloated.

The Low FODMAP Diet

The low FODMAP diet reduces diarrhoea, flatulence, bloating & distention, abdominal pain and constipation by reducing overall FODMAPs consumed to a level our bodies can tolerate. How much is tolerable? The answer will vary for each person. Just something else that makes us all so unique. Research has found adoption of the low FODMAP diet may cause relief of Irritable Bowel Syndrome (IBS) symptoms in up to 75% of sufferers (that’s a lot!) It is currently the only medically prescribed dietary treatment for IBS, and therefore requires administration by an appropriately trained professional (dietitian or nutritionist). The dietitian will make sure your diet remains balanced, varied and nutritionally adequate, which can be quite challenging on such a restrictive diet.

Below are just some examples of low and high FODMAP foods. Remember that foods are constantly being tested and added to this list, and foods that have already been tested are periodically re-tested as FODMAP content can change due to environmental and growing conditions, climate etc. For the most accurate updated information, download the Monash Low FODMAP smartphone app.

Food Category High FODMAP Foods Low FODMAP Food Alternatives


High: Asparagus, artichokes, onions(all), leek bulb, garlic, legumes/pulses, sugar snap peas, onion and garlic salts, beetroot, Savoy cabbage, celery, sweet corn

Alternatives: Alfalfa, bean sprouts, green beans, bok choy, capsicum (bell pepper), carrot, chives, fresh herbs, choy sum, cucumber, lettuce, tomato, zucchini


High: Apples, pears, mango, nashi pears, watermelon, nectarines, peaches, plums, banana (ripe)

Alternative: Banana (unripe), orange, mandarin, grapes, melon.

Milk and dairy:

High: Cow’s milk, yoghurt, soft cheese, cream, custard, ice cream

Alternative: Lactose-free milk, lactose-free yoghurts, hard cheese

Protein sources:

High: Most legumes/pulses

Alternative: Meats, fish, chicken, firm tofu (in water), tempeh.

Breads and cereal:

High: Rye, wheat-containing breads, wheat-based cereals with dried fruit, wheat pasta Gluten-free bread and sourdough spelt bread, rice bubbles, oats, gluten-free pasta, rice, quinoa

Alternative: Biscuits (cookies) and snacks Rye crackers, wheat-based biscuits Gluten-free biscuits, rice cakes, corn thins

Nuts and seeds:

High: Cashews, pistachios

Alternative: Almonds (<10 nuts), pumpkin seeds.

It’s important to note that foods on the high FOMDAP list aren’t “bad” for you. They are simply potentially problematic for IBS sufferers when consumed in excess or too regularly. The low FODMAP diet is restrictive and should be temporary. This is because this style of eating cuts out many nutrient and prebiotic-rich foods.

A low FODMAP diet involves three phases:

1. Elimination: can last from 3 to 8 weeks depending on response. Here a person eliminates all high FODMAPs from their diet. It’s the least fun and most restrictive phase.

2. Reintroduction: Once the elimination phase is over, individuals can start reintroducing FODMAP types into their diet one at a time (e.g., oligosaccharides one week, monosaccharides another week), about every 3 to 7 days, to see which foods trigger their symptoms. This is where a dietitian becomes crucial.

3. Maintenance: The maintenance phase involves aiming to eat as normally as possible, while still limiting the FODMAP foods that cause IBS symptoms (you would have identified your culprits during reintroduction). Eventually, some people may be able to incorporate all or most FODMAPs back into their diet with no symptoms (hooray!).

PERKii’s range of probiotic drinks would be classed as moderate – high FODMAP due to the addition of natural apple juice (apples are a high FODMAP fruit). This means they are the perfect drink to introduce during the re-introduction phase, as the probiotics in this nutrient-dense drink (Lactobacillus casei Microgel) are likely to buffer against the high fructose content of apple, and deliver a hit of important bacteria directly to the gut. As many IBS sufferers have quite profound gut dysbiosis (imbalance of bad: good bacteria), we need as many probiotics (healthy bacteria) as we can get!

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