Frequently asked questions in the area of diet and IBS

  1. I am a 'fructose malabsorber' and have been told I have IBS; do I have to restrict fructose/FODMAPs?
  2. I am a 'fructose malabsorber', but I do not have IBS. Do I have to restrict fructose/FODMAPs?
  3. I was tested for fructose and lactose malabsorption and my breath testing was negative. Does this mean there is nothing diet can offer to control my IBS?
  4. Is there any association with parasites or gastroenteritis and IBS?
  5. What is the difference between 'gluten-free' and 'wheat-free' foods? Do I have to restrict gluten?
  6. How does sucrose (table sugar) fit into the low FODMAP diet?
  7. What happens if I break the diet?
  8. Is this a life-time diet?
  9. What about other strategies to manage IBS (e.g. probiotics)?
  10. Is there anything else that can improve the absorption of FODMAPs?

1. I am a ‘fructose malabsorber’ and have been told I have IBS; do I have to restrict fructose/FODMAPs?

Yes. If you have received the diagnosis of IBS, and via breath testing it has been discovered that you ‘malabsorb fructose’ then you need to restrict excess fructose as well as other FODMAPs (fructans, GOS and polyols) in your diet. We highly recommend you see a Dietitian with experience in this area. They will guide you through appropriate exclusion of FODMAPs followed by a structured re-introduction of FODMAPs back into your diet. You may find you can tolerate small amounts of excess fructose (and other FODMAPs) without exacerbating your symptoms.

2. I am a ‘fructose malabsorber’, but I do not have IBS. Do I have to restrict fructose/FODMAPs?

No. Fructose malabsorption is a normal phenomenon and FODMAPs only need to be restricted if they induce undesirable gastrointestinal symptoms (i.e. associated with IBS).

3. I was tested for fructose and lactose malabsorption and my breath testing was negative. Does this mean there is nothing diet can offer to control my IBS?

No. The oligosaccharides (fructans and GOS) are ‘malabsorbed’ in everyone, so these FODMAPs are very likely to induce symptoms in people with IBS. Malabsorption of polyols (e.g. sorbitol, mannitol) are not routinely tested, however they may also induce symptoms. Therefore, it is likely you will benefit from restricting fructans, GOS and polyols. A specialist dietitian can help you determine which of the other FODMAPs are likely triggers for you.

4. Is there any association with parasites or gastroenteritis and IBS?

There is evidence that up to almost 1/3 of people who suffer a bout of gastroenteritis go on to develop ongoing gut symptoms known as post-infectious irritable bowel syndrome (PI-IBS). The risk of developing PI-IBS increases if the bout of gastroenteritis beforehand is particularly severe or long-lasting. It is thought that gastroenteritis can change the type and amount of bacteria in the gut, cause ongoing inflammation and/or damage the lining of the gut which can lead to these ongoing symptoms.

5. What is the difference between ‘gluten-free’ and ‘wheat-free’ foods? Do I have to restrict gluten?

A strict life-long ‘gluten-free’ diet is only required if you have been diagnosed with coeliac disease. Coeliac disease is an auto-immune condition that results in inflammation of the small intestine when any gluten is ingested. Ensure you are properly investigated for coeliac disease before restricting gluten in your diet. When following the low FODMAP diet, fructans and other FODMAPs, but not gluten, are restricted. Gluten is the protein found in wheat, rye and barley. These cereals also happen to be high in FODMAPs (mostly fructans). ‘Gluten-free’ foods are usually based on rice flour, maize- or corn-flour, potato-flour and quinoa which are low in FODMAPs, so by choosing ‘gluten-free’ you may also be choosing low FODMAP. Keep in mind, ‘gluten-free’ foods may have high FODMAP ingredients added (e.g. onion, pear or honey) so read the ingredient label carefully. Choosing a strict gluten free diet when you only require a low FODMAP diet will lead to over-restriction. Oats and spelt bread contain gluten but are relatively low in FODMAPs so are suitable to have on a low FODMAP diet in appropriate serves. In addition, gluten is found in products derived from wheat, rye and barley, such as wheat starch, wheat thickeners and barley malt. These are common ingredients in a wide range of commercial products including soy sauce, confectionary, mayonnaise, yoghurts and more. They contain gluten and must be avoided on a gluten free diet for coeliac disease, BUT they are not high in fructans and are suitable to include in a low FODMAP diet.
‘Wheat-free’ refers to any food that does not use wheat in the manufacturing, but ‘wheat-free’ foods may still include ‘gluten-containing’ cereals such as rye, barley, oats and spelt and “fructan-containing” cereals rye and barley. Wheat-free does not necessarily mean that it will be low in FODMAPs. The ingredients of products claiming “wheat free” should be checked for other FODMAP-containing foods.

6. How does sucrose (table sugar) fit into the low FODMAP diet?

Sucrose is a disaccharide (2 sugar units) made up of equal parts of glucose and fructose. Sucrose is broken down and absorbed efficiently in the small intestine. Small amounts (e.g. 1 or 2 teaspoons in a hot drink or a small handful of lollies) are usually well tolerated. For some people with IBS, large amounts of sucrose may be poorly tolerated and so it is best to limit large doses (e.g. a large serve of regular soft drink).

7. What happens if I break the diet?

The main aim of a low FODMAP diet is to achieve good symptom control. Occasional intake of FODMAPs may not induce symptoms when the overall load of FODMAPs is reduced. If you do experience gastrointestinal symptoms, return to a strict low FODMAP diet and symptoms should improve within 1–3 days.

8. Is this a life-time diet?

No. It is recommended that the full restriction of a low FODMAP diet is followed for 2-6 weeks and then your progress should be reviewed by a dietitian. The dietitian will help advise which foods (and how much) can be gradually re-introduced into your diet. Diets should be tailored for each individual’s needs. Many people can return to their usual diet, with just a few high FODMAP foods that need to be avoided in large amounts. Recent research has also shown that following a strict low FODMAP diet in the longer term can reduce levels of certain beneficial bacteria in the gut. For this reason also, it is advised not to follow an unnecessarily strict low FODMAP diet and to see a specialist Dietitian for appropriate re-introduction of FODMAP-containing foods. This is the focus of current research.

9. What about other strategies to manage IBS (e.g. probiotics)?

Probiotics are live micro-organisms that confer some health benefits in the gut. There is some evidence that probiotics can help with IBS symptoms, but this may vary depending on which probiotic preparation is used.
We recommend that you try one management strategy at a time; commence the low FODMAP diet first. If you have not achieved good symptom control after 2-6 weeks on the diet then at review with the dietitian discuss other management strategies and the possibility of introducing probiotics.

10. Is there anything else that can improve the absorption of FODMAPs?

We are currently researching the role of glucose in assisting the absorption of excess fructose. However results of these trials are still pending.  We do know that lactase enzyme products (available from pharmacies as drops or tablets) can be used to break down the lactose present in milk and other dairy products. These may be worth trialling if you have lactose malabsorption.