From time to time I get asked questions from journalists about the low FODMAP diet. I thought it would be useful to put some of these questions on the blog along with the answers I gave. You can also see the articles they went into here.

Common journalist questions on the low FODMAP diet

– Do you know how many people have a problem with digesting FODMAPS?  Are there any statistics?

The problem is not from digesting FODMAPs but rather the symptoms experienced by those with IBS from digesting FODMAPs.  All FODMAPs will be absorbed differently by different people. There are no statistics for this although up to 20% of the world population may have IBS.

– How does fructose malabsorption link with a general FODMAP ‘issue’ for people?

Fructose is only a problem when it is in excess of glucose within a food, or the food contains a high amount of added fructose. Most people will ‘malabsorb’ fructose if you give them enough fructose.  As part of the low FODMAP diet restriction phase fructose is avoided along with the other FODMAPs.

– It looks as though there have been 15 studies on how FODMAPS relate to IBS.  Is that right?

There are more studies coming out across the world all the time which is encouraging.  The best review of studies so far is by the FODMAP team at King’s College London (not that I’m biased!). You may be able to access the full paper here.

Any idea why some people and not others have this issue with FODMAPS?

Visceral hypersensitivity, anxiety / stress and the gut microbiota in particular are interesting factors. These factors are all difficult to study and there are many unknowns in the field of IBS.

– Any links to what exactly happens in the gut?  Why people can’t digest them properly?

Lactose requires lactase for digestion, fructose is absorbed via gut transporters,  polyols are absorbed passively while humans lack enzymes to digest the oligosaccharides (FOS and GOS) which are digested for us by bacteria in our gut. Everyone will have different absorption capacities due to the different absorption process briefly mentioned. FODMAPs collectively all have the same effect on the gut; they increase the amount of water entering the small intestine and produce fermentation in the large intestine leading to symptoms of pain, bloating, wind, diarrhoea and even constipation.

– How long is it before people on the diet tend to see results?

For the vast majority roughly 4 weeks with most of these improving between 1-2 weeks.  However it can take up to 8-12 weeks for some.

– Once people follow the terms of the diet, are they then able to relax the exclusions (ie, does the gut heal and they can then tolerate FODMAPS) or is this a life-time diet plan?  I understand that the intolerances won’t be the same for all people.

The most important part of the low FODMAP diet is the reintroduction phase where you challenge high FODMAP foods systematically to assess your tolerance levels to the different FODMAPs.  The low FODMAP diet should only be followed for a few weeks, preferably under the supervision of a registered dietitian.  I think it is unfortunate that many people may follow a low FODMAP restriction diet for life because they have not sought the correct advice.  The aim of the diet is to educate people to be able to self-manage their IBS symptoms allowing them to eat as much variety of foods as possible, including high FODMAP foods, but without eating too many foods that trigger symptoms.  You will only find out the answer to this by completing the reintroduction phase and working out your personal tolerance levels.By the way not eating FODMAPs does not ‘heal’ the gut. FODMAPs do not damage the gut in any way.

– What other conditions is it useful for, apart from IBS?

The low FODMAP diet is an effective strategy for reducing symptoms of IBS. There may be applications for other conditions that have similar gastrointestinal symptoms such as Crohns disease or coealiac disease although there is a lack of research for the effectiveness of the low FODMAP diet in these conditions at present.

– Are probiotics included in this plan?

A dietitian may consider probiotics as an option after a trail of the low FODMAP diet.  The evidence suggests probiotics may be beneficial for those with IBS however what probiotic you should take, for how long you should take it and who it will be effective in is unknown. Taking a probiotic is kind of like playing the lottery – there will be winners and losers.

– Presumably prebiotics aren’t included?  This goes against many of the other ‘gut soothing’ diets that are around.

For those who experience symptoms from eating food containing FODMAPs a ‘gut soothing’ diet containing prebiotics such as FOS or GOS (both FODMAPs) will probably increase rather than decrease their symptoms.  However prebiotics are an important part of the diet and research has shown they can be beneficial for gut health.  This is another reason why the low FODMAP diet should only be used for a short period and preferably under the guidance of a qualified dietitian trained or experienced in the low FODMAP diet.

Here is a link to some of the full articles relating to these questions and many more. They are all good articles based on the research behind the diet so worth a read.

We are currently travelling around the world and plan to bring you‘Around The World In 80 Low FODMAP Dishes’ – a collection of the best low FODMAP foods and recipes as we travel the globe. See more on our low FODMAP diet travel section.

Good news! The first ever book dedicated to reintroducing FODMAPs is now available to purchase on Amazon Kindle. The book is titled ‘Re-challenging and Reintroducing FODMAPs – A self-help guide to the entire reintroduction phase of the low FODMAP diet’. Click on the logo for more details.


More information on Reintroducing FODMAPs here.

Low FODMAP recipes here.

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Lee is a UK Registered Dietitian who worked as a researcher at King’s College London University researching the low FODMAP diet for irritable bowel syndrome (IBS). Previously Lee worked for the NHS with many years’ experience of treating IBS. Lee has run a popular blog on the low FODMAP diet since 2013 where you can learn all about his experiences of following the low FODMAP diet, find information on the research behind the diet, the practicalities of implementing the diet along with low FODMAP meal and baking recipes. This year Lee has published the first ever book dedicated to the reintroduction phase of the low FODMAP diet. More information on the book entitled ‘Re-challenging and Reintroducing FODMAPS: A self-help guide to the entire reintroduction phase of the low FODMAP diet’ can be found on the website

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