Blog Post

What to Do if the Low Fodmap Diet Does Not Work for You?

Low FODMAP foods

The low-FODMAP diet is one of the main options for managing irritable bowel syndrome (IBS). But what is the next step if it does not work for you?

This is a very relevant point. Because the research we have on FODMAPs indicates that the low FODMAP diet seems to significantly improve symptoms in 50-86% of people.

Which brings up the obvious point – what about the people 14-50% of people it does not help? Or what other options could you explore if it did help, but you still have symptoms you want to address?

This post is designed to comprehensively cover a lot of those aspects.


Low FODMAP Foods

The first aspect to address is whether you were 100% on the Low-FODMAP diet.

In the most empathetic way possible, I want to highlight that the low-FODMAP diet is hard.

It is hard to know what foods are high FODMAP foods without constantly having to look it up. And it is hard to avoid those foods once you know.

It is also hard to go from 0-100 in terms of knowing everything you need to know. A lot of people hear about FODMAPs and are starting the diet not long after.

Personally, as a dietitian working in this space, it took me around 2 years before I could comfortably identify almost any food as high-FODMAP or low-FODMAP. Like some of it is obvious, but other foods are less obvious.

To repeat, it took around 2 years.

Obviously, we have options like our comprehensive list of FODMAP containing foods which you can use to easily search ingredients and solve this problem. But if it took me around 2 years to be relatively confident, it is a big ask to assume you have nailed it without a lot of experience off the bat.

Another aspect is that some people do not appreciate that to do the low-FODMAP diet, you need to DO the low-FODMAP diet. As in strictly low-FODMAP for 2-6 weeks depending on the planned timeframe.

Some people still have a higher FODMAP intake than desired during that phase, not fully aware of how that could be still causing symptoms.

I just wanted to touch on compliance first. In some cases, people might be looking for alternative solutions before really implementing the low-FODMAP diet well in the first place.


There is a gut-brain connection. They clearly communicate with each other. The brain impacts the gut and vice-versa.

If you are constantly stressed out, that could be the main thing causing your IBS. Even if you do not feel stressed out, there is a chance that it can still be that.

Gut-Brain Axis Diagram


People with IBS are more likely to have depression and/or anxiety.

Lifetime depression rate is 60% for those with IBS, compared to 20% in the average person.

40% of people with anxiety also have IBS.

Sometimes even antidepressants classed as selective serotonin reuptake inhibitors (SSRIs) may help regulate bowel signals in IBS-C (constipation). Treatment with SSRIs may stimulate nerve activity and restore normal nerve function between the brain and the intestines. 

Meanwhile, drugs that block serotonin receptors can be useful for diarrhea. 

A 2014 meta-analysis showed 50% of IBS patients benefit from cognitive behaviour therapy and 70% benefit from gut-directed hypnotherapy.

Addressing depression and anxiety can be helpful, if possible.

Another addition I have that I use with my clients is that I encourage the use of an app called Nerva, which utilizes gut-directed hypnotherapy.

Gut Directed Hypnotherapy Stats

Gut-directed hypnotherapy seems around as effective for managing IBS as the low-FODMAP diet does. It is worth trying out in some way to see if it helps.


Different Types of Probioti

Probiotics are often overhyped, but they could play a role in helping to manage IBS symptoms.

Probiotics featuring Bifidobacteria and Lactobacilli seem to be the most effective at this stage.  

These bacteria populations are typically low in people with IBS. But there are no real clear-cut recommendations because the research is all over the place still. 

A review by the British Dietetic Association of 29 studies showed 14 different studies had positive results, using 10 different probiotics. While things look relatively promising they are still kind of inconsistent.  

Benefits can take up to 3-4 weeks to be noticeable. It is also recommended to do this as a standalone treatment to tell if a change in symptoms is related to probiotic use or not.  

Overall Gut-Health

Your overall gut health and the quality of your gut microbiome could be playing a factor in the symptoms you are experiencing.

While there is no “gold standard” gut microbiome, variety of bacteria seems to be a good sign.

And there are other clues too. For example, those with IBS who experience pain typically have over 5x fewer Bifidobacteria than those without pain.

There are also signs that it makes sense to focus on short-chain fatty acids (SCAs) such as butyrate as well. The catch with this is that a lot of the foods that help the production of butyrate also happen to be high FODMAP.

One thing you can focus on though is to aim for >30 different plant-based foods per week. This is probably a good idea for most people, as it is consistently linked with what is typically considered “good” gut health.

It also is not as hard as you would think. For example, instead of having a handful of one specific type of nut, you could have mixed nuts and seeds that have 5+ different options. You can have 3-5 different vegetables at lunch and another 3-5 at dinner. It is often easier than it sounds.

30 different plant based foods example
Image Credit to Gemma Sampson –

Avoiding Restriction and Extended Periods on Low Calories

One statistic that clearly stands out to me is that ~50% of people diagnosed with an eating disorder have IBS.

Doubling down on that, 98% of those admitted into an eating disorders unit have a functional gastrointestinal disorder (constipation, diarrhea, reflux, bloating or dysphagia).

Those are startling statistics. It also adds further weight to the current stance of most experts in this space who recommend that the low FODMAP diet is NOT used with anybody who has an eating disorder or is at risk of an eating disorder.

This obviously goes alongside the obvious aspect of the low FODMAP diet adding further restriction as well, which would not be desired under those circumstances.

Another similar area that I find relevant is that a large percentage of bodybuilding competitors (across all categories) end up experiencing IBS symptoms during their competition preps. And these symptoms typically last 6+ months after the show.

This can be due to a combination of restriction, as well as relative energy deficiency syndrome (RED-S).

RED-S can lead to a reduction in energy expenditure utilised for digestion by the body, to conserve energy overall. But this can make digestion less effective, which could contribute to symptoms.


Fibre Containing Foods

There are different types of fibre and honestly, it is a pretty deep rabbit hole. I do not want to go too deep down that rabbit hole for this article though.

One basic thing to try out though is playing around with the types and amounts of fibre.

Firstly, typically soluble fibre seems to be slightly better for most IBS symptoms. But I will touch on that more later.

The main thing I wanted to touch on with this section is the AMOUNT of fibre.

Everybody always says to INCREASE your fibre intake. And there is a fair amount of merit to that claim.

But if you are working to increase your fibre, you should take a slow and steady approach. Quick jumps in fibre typically actually make symptoms worse.

Beyond that, sometimes REDUCING fibre intake could improve symptoms as well, particularly if you previously had a very high fibre intake.

If you feel like you have been trying one approach for ages with no success, it might be worth going the other direction and seeing what happens.

If you notice no difference, then I would just go back to slowly increasing your fibre up to a relatively high level, since that typically comes with a lot of other benefits too.

Vitamin D

Vitamin D3

Vitamin D is rarely mentioned when it comes to IBS. A large reason for that is that there is not much research on it, for this specific condition.

So, there are not many strong claims to be made yet. But a study in 2015 from Saudi Arabia identified that 82% of people with IBS were deficient in vitamin D, compared to 31% of control participants.  

Another study from 2016 put this to the test and got 90 people with IBS and got them to supplement 50,000IU vitamin D every fortnight for 6 months. There was a significant improvement in almost all symptoms, but it did not completely solve the IBS on average. 

At this stage, there is not much research on the topic. A 2022 meta-analysis on the topic covering the 4 relevant studies that we have so far indicates that vitamin D supplementation can help improve IBS symptoms. But it is too early to make a strong conclusion.

Even if it turns out that vitamin D is not beneficial for IBS, if your blood levels were low, or on the low end of the healthy range, you would benefit from supplementation or addressing it regardless. It is also cheap and safe unless supplemented at an excessively high level.

IBS Basics – Fat Intake, Caffeine and Spicy Food

Technically the gold-standard front-line approach involves checking basics first before undertaking the low-FODMAP diet.

It involves trying to reduce stress, as discussed earlier.

But it also involves avoiding high-fat foods, caffeine and spicy foods.

In regard to fat intake, the mechanism makes sense. Give somebody who is accustomed to a low fat intake, a large amount of fat in one sitting and it will often cause IBS symptoms. So that point is valid.

But it seems like if you get a group of people with IBS symptoms to try to reduce their fat intake, there is not much evidence yet to suggest that reducing fat intake will help many of them. That’s not to say it cannot help, just that we have more clear-cut evidence for other factors.

With caffeine, that one also makes sense. Caffeine acutely stimulates bowels in a lot of people, which could trigger symptoms. Beyond that though, it could also indirectly contribute to symptoms by increasing anxiety.

Spicy food once again could play a role. Playing around with limiting/avoiding it and seeing if it makes a difference also could help. That being said, I am yet to see somebody with IBS where it has been as simple as just avoiding spicy food.

Peppermint Oil

Peppermint Oil

Peppermint oil can also help IBS symptoms. It is most effective for bloating but could help with other aspects.

The most extensive review of peppermint oil included data from over 800 patients from twelve clinical trials. The review showed IBS symptoms were 44% less common in patients who took the peppermint oil compared to those who took a placebo.

The standard dosage is 0.2-0.4ml (usually one capsule if in capsule form) 3x per day before meals. 

Peppermint tea does not appear to have the same effect as peppermint oil – although it would not be detrimental.

Constipation Specific Nutrition

Standard advice when it comes to constipation typically involves increasing fibre, fluid and exercise.

But food for thought:

  1. Increasing fibre intake does not always help. In some cases it can help, in others it might make it worse.
  2. The mechanism related to fluid makes sense, but if you get a group of people with constipation and have them try drink more water, there usually is no improvement in symptoms.
  3. The exercise part is valid and makes a big difference for most people. But what if you already exercise regularly and still get symptoms?

Other specific nutrition advice for constipation that actually will help is below:

  1. Trial 5-10g psyllium husk or a serving of Metamucil each day. This appears to help all symptoms of constipation including frequency, ease in passing stools, bloating and pain.
  2. Have 2x kiwifruit per day. Kiwifruit contains an enzyme called actinidin which helps stimulate the bowels.
  3. Add 10-20g of linseed/flaxseed per day. Start low and increase over time. This seems to help most symptoms as well, potentially due to the soluble fibre content.

RPAH Elimination Diet

Another option worth looking into is the RPAH Elimination Diet (also know as the Failsafe Diet).

This is a complex diet. But it involves reducing food chemicals in the diet (both natural and added), which can play a significant role in IBS symptoms.

It is a less popular approach, but I am aware of other dietitians who actually use this BEFORE looking at FODMAPs because they believe it is even more effective.

I do not use it with my clients on a regular basis, but it is certainly an option worth learning more about if you have tried other stuff without success.


While the low-FODMAP diet has a high success rate, there are a lot of reasons why it will not work for everybody.

Managing stress, mood, fibre intake and playing around with aspects like probiotics, overall gut health, food chemicals, vitamin D, peppermint oil and other aspects could potentially be the key to significantly improving symptoms.

By Aidan Muir

Aidan is a Brisbane based dietitian who prides himself on staying up-to-date with evidence-based approaches to dietetic intervention. He has long been interested in all things nutrition, particularly the effects of different dietary approaches on body composition and sports performance. Due to this passion, he has built up an extensive knowledge base and experience in multiple areas of nutrition and is able to help clients with a variety of conditions. One of Aidan’s main strengths is his ability to adapt plans based on the client's desires. By having such a thorough understanding of optimal nutrition for different situations he is able to develop detailed meal plans and guidance for clients that can contribute to improving the clients overall quality of life and performance. He offers services both in-person and online.