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When the low FODMAP diet doesn't work.

Updated: Jun 4, 2021

The low FODMAP diet can work brilliantly to reduce gut symptoms such as bloating and excess gas and gut pain and diarrhoea and/or constipation if you are reacting to FODMAPs (small, poorly digested carbohydrates such as fructose). Sometimes the low FODMAP diet doesn't work! Or only partially works with significant gut symptoms continuing (and maybe other symptoms beyond the gut- see below).

Possible scenarios:


Maybe there are some sneaky high FODMAP foods causing issues: best to troubleshoot with an experienced Dietitian in FODMAPs PLUS food intolerances (see why later).

General non FODMAP triggers such as meal size, stress, inadequate fibre or fluid, poor sleep, triggers such as chilli can also be considered. And stress- did I mention stress?


Maybe FODMAPs are actually fine for you and not causing your gut symptoms, and maybe the symptoms are not related to food.

It is super important to check with your GP and/or gastroenterologist to rule out medical conditions such as endometriosis, Coeliac Disease, Inflammatory bowl disease and any other medical issues that can cause the same symptoms as IBS.


Gut or IBS symptoms can be caused by other food intolerances such as dairy or wheat intolerance and/or it can be due to other components in food such as food chemicals and some food additives.

Food chemicals include: salicylates, amines and glutamates as well as some food additives.

If the low FODMAP diet has not helped or has only partially resolved symptoms, it may be worth exploring these other food intolerances especially if you feel you have symptoms related to food.

If you or your child has following food symptoms, then you are looking at something different to (or as well as) FODMAPs as FODMAPs only affect the gut. It is worth noting that other food intolerances can also affect the gut.

These other issues point to other food intolerances.....

Headaches and migraines can be triggered by some foods

- Headaches and migraines

- Extreme fatigue (feel like been hit by a bus)

- Flu like aches and pains

- Mouth ulcers

- Skin issues eg rashes or hives or eczema flare up or itchy skin

- Fuzzy or foggy thinking

- Sinus issues

- Mood changes

- Sleeping issues

Hard to regulate emotions

- Gets angry easily or defiant and disruptive and defies rules

- Sinus/congestion

- Silly over the top behaviour

- Hyperactivity or easily distracted and hard to focus

- Bed wetting and sneaky poos

- Sleeping issues, night terrors

- Rashes, eczema flare up, itchy skin

It is important to seek advice from your doctor to check there is no underlying equal issues causing any of these symptoms.

Once medical issues are eliminated and if your symptoms warrant it, it may be worth exploring food intolerances to help you manage your ongoing gut symptoms as well as symptoms that go well beyond the gut.

It is a great idea to choose a Dietitian specialising in FODMAPs AND food intolerances while also understanding allergies and Coeliac Disease as possible scenarios will help you arrive at your best diet sooner.

So in summary, food issues can be caused by:

- FODMAPs (but only gut symptoms)

- Whole foods or food allergies eg dairy or wheat

- Food chemicals and some additives

A combination of the above may be required, and as everyone is different, a proper assessment is important to try and work out your best fit.

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