20 August 2018
Many, but not all people will experience an improvement in their IBS symptoms during the first 2-6 weeks on a low FODMAP diet. While a poor response to the diet can be disheartening, there are a number of very good reasons to explain this. Working with an experienced dietitian will help you to understand why your symptoms improved less than hoped, and to formulate a management strategy going forward.
You can assess your symptom response to a low FODMAP diet using the food and symptom diary in the Monash University low FODMAP App™. This diary allows you to track changes in your IBS symptoms as you follow the diet.
Alternatively, you can rate the improvement in your IBS symptoms on a simple, 0 to 100 scale. Ask yourself: ‘On a scale of 0 to 100, how much did my symptoms improve since starting a low FODMAP diet?’ Using this method, zero would indicate no improvement at all, and 100 would indicate total symptom relief.
When reviewing your symptom response, it is important to consider that:
If after 2-6 weeks on the diet, you consider that your symptom response was adequate, then it is time re-challenge. However, if not, work with your dietitian to figure out why.
There are a number of reasons to explain a poor response to a low FODMAP diet.
A low FODMAP diet is effective in most people with IBS, but not all. In fact, research shows us that around 50 to 80% of sufferers will experience an improvement in their IBS symptoms during phase 1 of the diet, leaving 20-50% of people who will not respond.
Comparing your symptoms before and after the first 2-6 weeks on this diet will help you to decide whether or not your symptom response was ‘adequate’.
If you adhered to the low FODMAP diet, but feel that the improvement in your IBS symptoms was inadequate, then FODMAPs should be re-introduced, and other therapies should be considered. Reintroduction of FODMAPs can occur slowly/gradually if you experienced a minor, but inadequate improvement in symptoms (to avoid any flare in your IBS symptoms). By contrast, FODMAPs can be reintroduced all at once if you experienced no improvement at all.
You may have achieved a suboptimal response to the low FODMAP diet if you did not sufficiently reduce your FODMAP intake. This may occur if you unknowingly consumed high FODMAP foods, or if you had trouble implementing the dietary restrictions. An experienced dietitian who is specialised in IBS can assess your low FODMAP diet, and determine whether you implemented the diet properly. Your dietitian may consider:
Another possibility is that you have another underlying diagnosed or undiagnosed condition that is contributing to ongoing gastrointestinal symptoms. Conditions with IBS-like symptoms include inflammatory bowel disease, coeliac disease and endometriosis. Although these conditions are relatively uncommon (and usually ruled out when your IBS is first diagnosed), if they have not been ruled out, you may need to arrange screening tests with your GP or a gastroenterologist.