What is the low FODMAP diet?

You might have heard people recommend a low FODMAP diet to help manage your symtpoms of IBS. But what exactly is it?  

FODMAPs are a group of carbohydrates found in a wide range of foods that are poorly absorbed in the small intestines.   

The term FODMAP stands for Fermentable, Oligosaccharides, Monosaccharides and Polyols - this is the scientific name given to groups of carbohydrates based on their chemical structure.   

As FODMAPs are poorly absorbed in the small intestine instead they reach the large intestines largely undigested. This can result in two things -   

  • Excess fluid; undigested FODMAPs can draw fluid from the body into the intestines that can increase the intestinal pressure. This can lead to diarrhoea.   
  • Fermentation - foods entering the large intestines are eaten by our gut microbiota as a result, gas is released and result in bloating.   

For those with IBS, their gut can be more sensitive to things like excess fluid and fermentation. Therefore, a low FODMAP diet is often used as the second-line approach for IBS (the first-line approach is dietary management).   

The goal of a low FODMAP diet is to find a personalised, modified FODMAP diet. This can be broken down into three stages -   

  1. Restriction stage; remove all high-FODMAP foods from the diet. This is done alongside a dietician to tailor the diet to your nutrient needs.   
  1. After following restrictions for 2-6 weeks (symptom dependent) you then introduce each FODMAP food one at a time - this will help you identify which FODMAP foods you are sensitive to and how much you can eat without triggering FODMAP symptoms.   
  1. Personalisation; this is tailored to each individual. This gives your diet flexibility and variation so you can stay on the diet long term. Tolerance can improve over time so re-assessing is encouraged.  

Staying on a strict low FODMAP for long periods can result in you missing out on large food groups and essential nutrients. This can also have a negative impact on your gut. Therefore, foods should be reintroduced slowly alongside a dietician.    

If you are interested in trying a FODMAP diet for your IBS, we would advise consulting with your GP to refer you to a dietician to ensure it is carried out safely and effectively.