Ask The Expert! A Dietitians guide to FODMAPS

by Eliot Gilzene, on 03/02/22 13:09

Our two-part dietitian’s guide.

If Google has left you feeling confused about FODMAPs you’re not alone.  We asked Magda Rzuczkowska, a specialist gastroenterology dietitian for the lowdown on when a low FODMAP diet can help, when it might make things worse…and what even is a FODMAP anyway?


What are fodmaps? 

‘FODMAPs (or Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) are a group of carbohydrates that can be responsible for digestive symptoms in some people with sensitive guts. FODMAP foods travel into the large intestine poorly digested. Once there our gut bacteria ferments them which can result in symptoms such as bloating, flatulence and abdominal discomfort. They can also draw water into the large intestine which can cause diarrhoea in some people.  

‘FODMAPs are found in a wide range of foods: 


Commonly found in wheat, rye, legumes and certain fruit and vegetables e.g. onion and garlic. 

Disaccharides (lactose)

Found in dairy and dairy products such as - yogurts.  

Monosaccharides (fructose)

Commonly found in honey, juices and specific fruits and vegetables such as mango. 


(mannitol and sorbitol)

Found in certain fruit and vegetables including: sweetcorn, avocado and certain sweeteners (especially those found in sugar-free gums and sweets). 


How does a low-FODMAP diet work?  

‘The diet consists of three stages: 

Restriction: ‘The idea is to give the gut a short break from high FODMAP foods to allow symptoms to settle. This stage usually takes four to eight weeks to complete. 

Reintroduction: ‘FODMAP foods are then systematically reintroduced, one at a time, to determine the ‘tolerance threshold’ for different types and quantities of FODMAPs. It’s rare for people to be sensitive to all FODMAP groups.  

Personalisation: The last stage is to ensure that you are still following a varied and balanced diet whilst avoiding some of the identified trigger foods.  

‘One of the common mistakes people make is to try to follow this rather complex diet without the support of a dietitian and getting stuck in the restriction phase, which can actually harm the gut by reducing the number of ‘good’ bacteria. It’s important to seek advice from a FODMAPs-trained dietitian who will assess your symptoms and diet and tailor the advice to find the safest and most effective way to make it work for you.’  

Find out whether - and how - a low FODMAPs diet might work for you with part 2 of our dietitian’s guide to low FODMAPs diets