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The low FODMAP diet didn’t work, what next?

Updated: Oct 3, 2021

The low FODMAP diet provides symptom relief for 75% of people with IBS. But unfortunately, that means that 25% of people don’t get the results they were hoping for and are left wondering what to do next.

If you are one of these people, read on to find out what your next steps may be…

IBS dietitian Kingston

Check you followed the low FODMAP diet correctly

The truth is that the low FODMAP diet is a pretty complicated one to follow and most people find that even with the proper guidance, they are likely to make mistakes, particularly in the beginning.

There are often FODMAPs hidden in foods which we may not have considered and unfortunately even small amounts of FODMAP can trigger symptoms in some people.

The low FODMAP diet should only be attempted with the support of a registered dietitian who can support you with following it correctly and ensure that you achieve a well-balanced diet whilst doing so.

Did you get a confirmed IBS diagnosis?

IBS can be a complicated condition to diagnose as there is no specific test to confirm it.

A diagnosis of IBS should be considered only if there is abdominal pain or discomfort that is either relieved by defaecation or associated with a change in bowel habit. This should be accompanied by at least two of the following four symptoms:

· altered stool passage (straining, urgency, incomplete evacuation)

· abdominal bloating (more common in women than men), distension, tension or hardness

· symptoms made worse by eating

· passage of mucus.

All people presenting with IBS symptoms should be clinically assessed for ‘red flags’ including signs and symptoms of cancer, inflammatory bowel disease (crohns and ulcerative colitis) and coeliac disease. A blood test and stool sample are usually required to exclude these diagnoses. Although best practice guidelines state that further testing is usually not required, some practitioners will arrange further testing such as a colonoscopy or endoscopy if they consider it appropriate.

If your GP or consultant has given you a diagnosis of IBS and you have trialled dietary modification including the low FODMAP diet with no improvement, then your GP may refer you to a gastroenterologist to explore other causes. Other possible causes include small intestinal bacterial overgrowth (SIBO), gastroparesis and diverticular disease.

Tip: If you are not sure about your diagnosis go back to your GP.

Consider Taking Probiotics

A Probiotic is defined as a micro-organism that when introduced into the host (human body) it should have beneficial qualities.

The use of probiotics in people with IBS may help to change the gut microbiota and improve the number of beneficial bacteria in the gut and reduce the number of unfavourable strains. Although probiotics have been researched considerably for their role in the treatment of IBS, there remains enough strong evidence to confirm which specific strains of bacteria or doses may be the most beneficial. This may in part be because everyone’s gut bacteria are different and therefore the required strain and dose of probiotic may vary between individuals.

It may be worth trying a probiotic, ideally one with multiple strains of different bacteria. You should take it for at least 4 weeks before deciding whether it has worked or not. If you see no improvement in symptoms after 12 weeks, then you should stop taking it.

Most people who see an improvement in their symptoms find that they must take the probiotic continuously or their symptoms return.

Although the elimination phase of the low FODMAP diet should not usually be followed for longer than 8 weeks, I often see people who haven’t had any guidance and may have been following it for much longer. Unfortunately, studies in recent years have shown that this can lead to unfavourable changes to the gut microbiota which can cause increased gut sensitivity. Researchers at Kings College in London found that taking a probiotic may help to offset these changes.

Tip: Trial a probiotic for at least 4 weeks before deciding if it has worked. If you notice no improvement after 12 weeks, then stop taking it.

IBS dietitian Kingston

Balance Your Fibre Intake

Fibre is an important component of the diet, it helps to keep our guts healthy and promotes regular bowel movements. Foods high in fibre include fruits and vegetables, beans, pulses, nuts, seeds and wholegrains.

Fibre can be a complicated topic when it comes to the management of IBS. A common mistake is to try introducing fibre into your diet too quickly. In practice I often see clients who set out to improve their diet to optimise their health or transition on to a plant-based diet and as a result their fibre intake doubles or even triples overnight.

As a starting point, if your symptoms are diarrhoea predominant then try reducing your fibre intake and then gradually increasing it again. If your symptoms are constipation predominant try gradually increasing your intake of fibre.

Tip: Increasing your fibre intake should always be done gradually to give your gut time to adjust.

IBS dietitian Kingston

Limit your intake of caffeine, alcohol, spicy and fatty foods

The above are potential gut irritants and are likely to contribute towards IBS symptoms. If you are currently consuming caffeinated drinks such as tea and coffee regularly, try and limit them to a maximum of 2-3 caffeinated drinks per day.

Alcohol is a potential gut stimulant, if you notice your symptoms are worse when drinking alcohol try and limit your intake to a maximum of 2 units per day. This is equivalent to approx. 1x 175ml glass of wine, a pint of beer or 2 single spirits. You should also try to only consume alcohol with food rather than on an empty stomach.

Although the mechanism is not clear, fatty foods have been shown to exacerbate symptoms in some people with IBS. If you have tried following the low FODMAP diet but your symptoms persist, be aware of whether fatty foods such as takeaways, cakes, pastries, butter, and cooking oils may be making you feel worse.

The ingredient capsaicin in chilli has been shown to worsen symptoms in people with IBS, particularly women. Again, if you notice your symptoms are worse following consumption of spicy foods then try removing spicy foods from your diet.

Tip: Try alternating your tea and coffee with decaffeinated options.

Practice Intuitive Eating

In some cases, IBS symptoms are exacerbated when you are not eating according to what your body needs. You may be swinging between going for long periods without eating, to eating large portions in one sitting. In doing so you may be putting your digestive system under strain.

Eating intuitively means that you are paying attention to your body’s hunger and satiety signals and therefore eating when you are hungry and stopping eating when you are no longer hungry. By eating intuitively, you are more likely to be following a little and often approach to eating which may be better tolerated by your gut.

Tip: Take your time when eating to be able to recognise when you have had enough. It takes approximately 20 minutes for your stomach to signal to your brain to tell you when you are full. If you eat very quickly you could easily eat quite a lot in one sitting before realising you have had enough.

IBS dietitian Kingston

Stress, Anxiety and Mood

Stress, anxiety and low mood have been shown to be significant contributors to IBS symptoms. Research has shown that people who have IBS are more likely to suffer with depression.

We have all heard of the phrase a “nervous tummy” and this may be explained by the “gut-brain axis” which consists of communication between the emotional and cognitive centres of the brain and the intestines.

Managing stress can be a difficult thing to master, particularly when most of us tend to lead busy lifestyles. Taking time out to relax, taking part in regular exercise and cognitive behaviour therapy are all useful tools.

If you suffer from depression and/or anxiety then your GP may recommend a mild dose of anti-depressants which have been shown to improve IBS symptoms in some cases.

More recently, gut hypnotherapy has been studied as a method to help “fix” the miscommunication between the gut and the brain. A study at Monash University in Australia compared the benefits of using gut directed hypnotherapy with the benefits of doing the low FODMAP diet and found it to be equally as beneficial for providing symptom relief. As a starting point I recommend a trial of the gut hypnotherapy app Nerva to my clients. If they start to see signs of improvement, then this suggests they may benefit further from 1:1 gut hypnotherapy.

Tip: Consider exercising regularly, taking time to relax, meditation or gut hypnotherapy.

Eat lots of plant-based foods

An imbalance in gut bacteria may be a contributing factor to your IBS symptoms. Bacteria in the gut are critical for normal gut development and health. A key factor supporting this is that IBS often develops after an episode of gastroenteritis (“stomach upset”) which has been shown to alter the number of bacteria in our gut. Additionally, multiple studies have shown that people with IBS have fewer strains of gut bacteria present compared with healthy controls.

By eating a well-balanced diet and in-particular focussing on consuming a large variety of different plant foods can help to optimise your gut health and repair any imbalance in gut bacteria. It is recommended that we should try to eat 30+ different plant-based food sources per week. This is likely to explain why in practice I often see clients who transition to a plant-based diet see an improvement in their IBS symptoms.

Tip: Aim to include 30+ different plant-based sources in your diet each week.

IBS dietitian Kingston


Whilst the low FODMAP diet has high success rates in the management of IBS, 25% of people unfortunately do not see any benefit from following it.

Considering taking probiotics, limiting intake of caffeine, alcohol, spicy and fatty foods, adjusting dietary fibre and managing mood are all suggested methods which may help.


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