The low FODMAP diet is a therapeutic diet for irritable bowel syndrome (IBS). The low FODMAP diet consists of three stages:
- Restriction stage: All high FODMAP foods are restricted from the diet and substituted with low FODMAP alternatives. Guidance from a dietitian is critical at this stage in order to tailor the diet to your nutrient needs. If you don’t respond to the diet after six weeks, it is important to stop the diet and revert to your usual intake.
- Reintroduction Stage: This is a step-wise process during which individual high FODMAP foods are reintroduced into the diet. The purpose of this stage is to help you identify which FODMAPs you are most sensitive to and the amount of FODMAP you can tolerate. This stage can take several months to complete. A dietitian can ensure that you complete this stage correctly and can help you interpret the results which can be challenging.
- Personalisation stage: Once the reintroduction phase has been completed, a diet that is tailored to your personal FODMAP tolerance can be adopted. This stage is important as it increases the variety of foods in your diet to ensure that you are having a nutritionally balanced diet without unnecessary restriction.
The Restriction Stage of the Low FODMAP diet should not be followed for more than 6 weeks
- Confirm the diagnosis of IBS
It is important that your GP or Gastroenterologist confirms the diagnosis of IBS. As there is no diagnostic test available to confirm the diagnosis, it is important to rule out other conditions or diseases that can have similar symptoms to IBS. This involves a blood test to test for Coeliac disease. It is also important to check for any ‘red-flag’ indicators which include the following:
- unexplained and unintentional weight loss
- blood in the stool, rectal bleeding
- Family history of gut disorders including coeliac disease, inflammatory bowel disease, cancer of the bowel, or ovarian cancer
The dietitian can check that you have had the necessary investigations and refer you back to your GP if necessary.
2. Provide first-line advice for IBS
It is important to address other dietary and lifestyle factors before starting the low FODMAP diet. These include the following:
- Eating regular meals
- Limiting alcohol intake
- Reducing caffeine intake
- Ensuring fluid intake is adequate
- Cutting down on rich fatty foods
50% of people with IBS get symptom relief following the first-line advice
3. Provide support and low FODMAP resources
A dietitian can ensure that you follow the low FODMAP diet correctly and that your diet is nutritionally balanced. There is a vast amount of information on the low FODMAP diet available on the internet but it not always correct and can be misleading. A dietitian will make sure you have up-to-date information on the low and high FODMAP food sources and provide support with recipe adaption, eating out, and label reading.
4. Ensure your nutritional status is not compromised
Over-restriction of FODMAPs may compromise your intake of calcium, B vitamins, and dietary fibre. A dietitian can ensure that you are eating a balanced diet to meet your nutritional requirements. This is particularly important for vegetarians because common vegetable foods are high in FODMAPs, meaning protein, vitamin B12, iron and zinc intake may be inadequate.
5. Determine the long-term plan
Once symptom relief is achieved on the restriction stage of the low FODMAP diet, it can be tempting to remain on this restrictive diet. This is particularly true if this is the first time you have experienced symptom relief in a number of years. However, there are many reasons why the restriction stage should not be followed long term including the impact on the gut microbiota and nutrient deficiency.
FODMAP-trained dietitians can provide a systematic way of identifying which FOMAPs are problematic for you and the quantity that can be included in your diet in the long term.