Classic mistakes made on the low FODMAP diet

There is a huge amount of information on the internet on the low FODMAP diet – a lot of it is conflicting and confusing.   It’s best to get the help of an experienced dietitian.

This article will go through the problems with doing the low FODMAP diet from food lists you may get from google.

The low FODMAP diet trial completed incorrectly

Even with lots of preparation, it can be easy to miss things like:

• soy milk
• chewing gum
• hidden ingredients in processed foods
• excess intake of low FODMAP fruit
• supplements containing high FODMAP ingredients  such as inulin/FOS
• Wrong type of spelt bread
• Multiple foods containing moderate levels of FODMAPs (particularly fructans)  consumed in excess

Over-restricted diet

Often people are too strict with the low FODMAP diet.   A number of foods containing FODMAPs are ok in smaller quantities but are often cut out for no reason.  For example, there may be no need to cut out all fruit, all gluten or all dairy products.

Lack of understanding of how FODMAPs alter gut function

If you have constipation,  removal of some FODMAP groups (e.g. sorbitol) or reducing fibre intake (which have often happen on the low FODMAP diet) can actually make things worse.   If constipation gets worse, then you can have the problem of increased bloating, gas and stomach pain.  Having an understanding of how FODMAPs impact the gut is important.

Reduced nutrient intake

Reduced nutrient intake can occur especially if the person has additional food intolerances/allergies or alternative diets (vegetarian or vegan diet). Care needs to be also taken for people with a history or existing nutritional deficiencies.

Inappropriate low FODMAP trial for children

Working with a dietitian who has experience with children and IBS is crucial to ensure children get the right nutrition whilst doing the diet trial. In many cases, a more relaxed version of the diet can be just as effective with toddlers and older children.

Unsure of suitable brands

Having the knowledge of appropriate brands, where to buy these products and which products to be cautious of can help with food purchasing.

Staying on the diet long term

Many people are unaware of the importance of food-rechallenges once the elimination phase is finished.

In many cases people stick rigidly to the diet for long periods of time, which is not ideal. The low FODMAP diet is best used for a short period of time (2-6 weeks) to work out whether these foods are impacting on how the gut works.

Research shows that long term FODMAP restrictions reduce intake of prebiotics which are important for good gut health. A low intake of prebiotics can lead to becoming more sensitive to FODMAP containing foods over time and a drop in healthy gut bacteria.

Our blog on ‘Low FODMAP not for life‘ goes into a bit more detail on this topic.

Trialing the wrong approach or limited response to the diet

70-75% of individuals with IBS respond well to the low FODMAP diet however many other possible food intolerances exist.

When working with a dietitian experienced in IBS/functional gut disorder (FGD), an alternative elimination diet may be advised if symptoms are suggestive of other intolerances. Many people can have a range of intolerances (e.g. FODMAPs AND food chemicals) and may report a partial response only to the low FODMAP diet as a result.

Trial not appropriate

Often the diet is undertaken with little medical investigation. There are many possible causes of gut issues. IBS/FGD should only be suspected if a complete medical work-up has been performed by a GP and / or a gastroenterologist.

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Removing wheat from the diet can also delay the diagnosis of coeliac disease. (Or make excluding coeliac disease challenging). We find this is because often people are reluctant to gluten-load prior to testing (which is required for accurate diagnosis), particularly if they think wheat is a problem.

Limited response

The low FODMAP diet can often be used in combination with other therapies (e.g. pelvic floor physiotherapy or gut-focused hypnotherapy) and may be more effective than used in isolation. Working in a team situation with a dietitian and a gastroenterologist can also help with coordinating your approach to ensure nothing is missed.

Incorrect rechallenging

Different FODMAPs move through the gut at different rates and many people report delayed reactions. Reintroducing FODMAPs with the help of a dietitian will ensure you re-challenge correctly. This will help you work out how your body copes with FODMAPs accurately.

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