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Food, FODMAPs and IBS: What to eat and what to avoid

Scientific studies have shown that a low-FODMAP diet can significantly relieve irritable bowel syndrome (IBS) symptoms for many sufferers. In a new book, Dr Sue Shepherd and Dr Peter Gibson explain how to make it work for you.

What is IBS?

Irritable bowel syndrome (IBS) is one of a group of conditions called ‘functional gastrointestinal disorders’. This means that they cause disturbances in the function of the gut but don’t have any identifiable physical features such as ulcers, inflammation, thickening of tissues, lumps and bumps or abnormal blood tests — all of which would indicate a different condition. The diagnosis of IBS relies upon the types of symptoms experienced and their context, such as how long they have been experienced and when they occur.

What are the symptoms?

Sufferers can experience a broad range of symptoms including abdominal pain and discomfort, bloating, changes in bowel habits, heartburn, nausea, over-fullness and so on. Some of these symptoms originate in the upper gut (the oesophagus and stomach) while others originate in the bowel. Other symptoms or perceived symptoms can include excessive wind, unsatisfied defecation (incomplete emptying), passage of slimy mucus into the toilet bowl, a noisy abdomen (the noises are called borborygmi) and pain in the rectum. Tiredness is also common and its severity usually depends on that of the bowel symptoms. Muscle aches and pains (called fibromyalgia) occur in some people, while others experience an ‘irritable bladder’ (urinary frequency and urgency).

People with IBS often know that certain foods will trigger their symptoms and really want to know what they should or should not eat. It has been shown that dietary change is the major way in which sufferers of IBS attempt to help themselves. Unfortunately, until recently doctors tended to shy away from offering specific dietary advice, although they worked hard to eliminate poor eating habits (such as stress-filled meals or always eating on the run) and to avoid obvious dietary extremes (such as too many cups of coffee each day or a diet full of fat or devoid of fibre). Until the low-FODMAP diet, there was minimal scientific evidence that specific dietary changes helped people with IBS.

Dietitians with expertise in gastrointestinal nutrition and many doctors now recommend a low-FODMAP diet as a cornerstone of their treatment for people with IBS. The majority of IBS sufferers who have tried the diet have experienced greatly improved symptoms and a markedly reduced need for medication.

Certain food components can cause the bowel to distend by drawing in more fluid and rapidly generating gas when they are fermented by bowel bacteria.

The main dietary components that do this are known as fermentable, poorly absorbed short-chain carbohydrates. In other words, they are indigestible sugars that provide fast food for bacteria. Such sugars have been given the acronym FODMAP which stands for:

  • Fermentable — rapidly broken down by bacteria in the bowel
  • Oligosaccharides — fructans and galacto-oligosaccharides (GOS)
  • Disaccharides — lactose
  • Monosaccharides — fructose
  • And
  • Polyols — sorbitol, mannitol, xylitol and maltitol

If this seems too wordy to get your head around, just remember that 'saccharide' is simply another word for sugar. Polyols are what we call sugar alcohols — sugar molecules with an alcohol side-chain. You don’t need to know anything more than this. You may have heard of some of these sugars or seen them in ingredients lists.

FODMAPs are ‘fast food’ for the bacteria that live naturally in the large bowel. The large bowel (and the lower part of the small bowel) naturally contains billions of bacteria. If molecules are not absorbed in the small bowel, they continue the journey to the large bowel. The bacteria that live there see these food molecules as ‘fast food’ and quickly break them down, which produces hydrogen, carbon dioxide and methane gases.

Multiple types of FODMAPs are usually present in any one meal. Because they all cause distension in the same way once they reach the lower small bowel and colon, their effects are cumulative. This means that the degree of bowel distension can depend upon the total FODMAPs consumed, not just the amount of any individual FODMAP consumed. If someone who cannot digest lactose well and absorbs fructose poorly eats a meal that contains some lactose, some fructans, some polyols, some GOS and some fructose, the effect on the bowel will be 1 + 1 + 1+ 1 + 1 = 5 times greater than if they ate the same amount of only one of those. That is why we have to consider all FODMAPs in food when modifying our diet.

A low-FODMAP diet has been shown to work in the treatment of IBS symptoms in both the short and long term. Once you know how to follow the diet, it is self-directed and self-empowering, meaning there are no ongoing costs for consultations or drugs.

When you start a low-FODMAP diet you should avoid all FODMAPs — fructans, GOS, lactose, excess fructose and polyols. If you know you can completely absorb fructose, however, you need not restrict your excess fructose intake, and if you know you can completely absorb lactose, you need not restrict your lactose intake.

You should eat no more than one serve of ‘suitable’ fruits (see DOWNLOADS) per meal or sitting. One serve is usually one metric cup of cut-up fruit, or one whole piece of fruit, such as one orange or banana. You can enjoy many fruit serves each day, but you should allow two to three hours between each serve.

Table sugar (also called sucrose or cane sugar) should not cause symptoms if eaten in moderation. Sucrose is a double sugar made up of one part glucose and one part fructose. Large amounts of sucrose in one sitting may cause a problem for some people.

Onion is one of the greatest contributors to IBS symptoms. We recommend that you strictly avoid onion for at least two months. This means not only cooking without onion, but also avoiding packaged foods that contain onion ingredients, such as onion powder in soups and stocks. You may find that you can reintroduce onion into your diet, but this will probably be only in very small amounts. If you cook with onion but leave it on your plate, this will only reduce the fructan load rather than remove it, since fructans can leach out of the onion into the other ingredients during cooking. Garlic also contains fructans, though if you like the flavour, one to two cloves per recipe can often be tolerated by IBS sufferers. An even better way to enjoy the taste of garlic without the fructans is to use garlic-infused oil.

Fats and oils do not contain FODMAPs and nor do animal-based protein foods, such as meat, fish, chicken and eggs. However, plant-based protein foods, such as legumes and lentils, do contain FODMAPs and you may need to restrict your intake of these foods. FODMAPs typically occur in carbohydrate-based foods.

Vegetarians often consume large amounts of legumes as an important source of protein. However, these contain GOS and fructans. As there is a risk that your vegetarian or vegan diet will become nutritionally inadequate if you cut out legumes, your dietitian may advise you to allow a certain amount of these in your diet but exclude all other food sources of FODMAPs. The best approach will depend on your individual tolerance. Good news for vegetarians: tofu is low in FODMAPs, so can be included as a protein source.

A gluten-free diet is often recommended as a way of managing the symptoms of IBS. Many people claim that it effectively relieves the symptoms of IBS, and there are plenty of websites promoting gluten-free diets as a cure for everything from IBS to chronic fatigue syndrome and autism. Often these claims are not backed up by any scientific evidence.

A gluten-free diet could improve symptoms of IBS as it removes fructans, a type of FODMAP. Well-designed scientific studies that produce validated evidence are needed before we can blame gluten for symptoms of IBS in people who do not have coeliac disease.

If you need to follow a low-FODMAP diet, you must avoid eating wheat and rye in large quantities. This means avoiding breads, cereals, pasta and biscuits, but you can still enjoy such things as a breadcrumb coating on a chicken schnitzel, or wafer pieces in chocolate. A specialist dietitian can help assess your individual intolerance to wheat and rye products. The table on the next page gives common wheat-based products and suitable alternatives. Rye products contain fructans and so should be restricted. Some people, however, find they can tolerate rye bread, probably because we can eat only small portions of it at a time. Some people may tolerate small amounts of 100 per cent spelt bread. Once you have been on a low-FODMAP diet for several weeks and your symptoms have improved, it might be worth trying small amounts of rye and/or spelt products to assess your own tolerance to them.

Food Suitable options
Fruits Bananas, blueberries, grapefruit, grapes, honeydew melon, kiwifruit, lemons, limes, mandarins, oranges, passionfruit, paw paw, raspberries, rockmelon (cantaloupe), strawberries, tangelos, tomatoes
Vegetables Alfalfa, bamboo shoots, bean shoots, bok choy, broccoli, capsicum (pepper), carrot, celery, choko, choy sum, corn, cucumber, eggplant (aubergine), green beans, lettuce (butter, iceberg), marrow, olives, parsnip, potato, pumpkin (squash), silver beet, spinach, spring onion (green part only), squash, swedes, sweet potato, taro, tomatoes, turnips, yams
Milk products Lactose-free milk, rice milk, ‘hard’ cheeses including brie and camembert, lactose-free yoghurt, gelato, sorbets, butter and margarine
Grain foods Gluten-free bread and cereal products, amaranth, arrowroot, buckwheat, corn (maize), millet, oats, polenta, potato, quinoa, rice, sorghum
Sweeteners Sugar (sucrose), glucose, stevia, any other artificial sweeteners not ending in '-ol' (eg. aspartame)
Other Garlic-infused oil as an onion and garlic substitute, fresh and dried herbs and spices, chives, ginger, maple syrup and golden syrup as honey substitutes
Food Varieties containing FODMAPS Suitable alternatives
Flours, grains Wheat and legume products, including barley, bulgar, chickpea flour (besan),* couscous, durum, kumat, lentil flour,* multigrain flour, pea flour,* rye, semolina, soy flour,* triticale, wheat bran, wheat flour, wheaten cornflour, wheatgerm Arrowroot, buckwheat flour, cornflour and cornmeal (maize), custard powder, glutinous rice, ground rice, malt, oat bran, oatmeal, oats, polenta, potato flour, quinoa, rice (brown, white), rice bran, rice flour, sago, tapioca, wild rice
Cereals Wheat-based and mixed-grain breakfast cereals, bulgar, couscous, muesli, semolina Rice-based or corn-based breakfast cereals, rolled oats (porridge), baby rice cereal, wheat-free muesli (with minimal amounts of suitable dried fruit)
Pasta, noodles Noodles, pasta, gnocchi Mungbean (glass) noodles, rice noodles, rice vermicelli, soba noodles, gluten-free pasta
Breads, biscuits, cakes All breads, biscuits, cakes, muffins, croissants, crumpets and pastries containing wheat and rye, sourdough commercial breads, breadcrumbs Gluten-free breads, taco shells, maize tortillas, plain rice cakes and crackers, gluten-free biscuits, gluten-free cakes and pastries
Dairy foods, alternatives Regular milk, ice cream, soft cheeses
(in large quantities), yoghurt
Lactose-free milk, calcium-fortified soy milk,** lactose-free ice-cream, hard cheeses, most lactose-free yoghurts, tofu
Sausages and other processed meats (check for onion and dehydrated vegetable powders) Plain red meat, fish, poultry, bacon, eggs
Nuts, seeds Pistachios All nuts except pistachios, all seeds
Fruit, veges See table above See table above
Spreads, condiments Most commercial relishes, chutneys, onion-containing gravies, stock cubes, dressings and sauces, honey Jam, marmalade, golden syrup, maple syrup, peanut butter, soy sauce, tamari, vinegar
Beverages Coffee substitutes, large quantities of fruit juice, apple, pear and mango juices Water, rice milk, mineral water, soda water, soft drinks, tonic water, fruit juice (safe fruits only, 125ml per serve), tea, coffee, most alcohols
Fats, oils Large amounts of margarine and  dairy whip/table spread Vegetable oils, butter, ghee, lard, dripping,  small serves of cream
Others   Baking powder, baking soda, cocoa, gelatine, pure icing sugar, salt, xanthan gum, herbs, spices

*These contain GOS and fructans, but in small amounts as part of a recipe do not cause IBS symptoms in most people. You should assess your own tolerance.
**Soy milk is usually well-tolerated. Assess your individual tolerance.

Nutritionist’s note

Not all gut symptoms relate to IBS. It’s important to get a confirmed diagnosis from a health professional. A low-FODMAP diet is not suitable for everyone with IBS, can be difficult to do without help and can be very restrictive nutritionally if care is not taken. See our Health practioners directory.

42 Comments. Add yours

Niki Bezzant says:

Hi - hummus is made from chickpeas, so it's not recommended if you're eating a low-FODMAP diet. Hope that helps - Niki

Im just learning that I am possibly wheat intolerant and upon testing this out it has helped me to understand but also now be less tolerant of others foods leading me to try out the FODMAP. I have two questions.
1. Due to my current disability I was on high dose of laxatives but going wheat free have reduced this. Will FODMAP diet effect this as in lack of fibre?
2. I also found I break out in a rash if I drink beer and other FODMAPS say beer and wine are an issue but specify this in your list. Could you explain this more to me please.

Niki Bezzant says:

Hi Krissie - a properly formulated low-FODMAP diet should not be low in fibre - you just need to take care with it. If you're getting a rash I would suspect it's nothing to do with FODMAPs but more likely to be other things in wine eg sulphites - it would be well worth seeing a specialist dietitian who is an expert in this area for more personalised guidelines - diagnosis of IBS can be quite tricky and needs to be done properly. 

Niki Bezzant says:

Hi - honey is high in fructose, which is one of the FODMAPs that people can have trouble with. 

Niki Bezzant says:

They both contain lactose, so if you're in the elimination phase I'd say no. Once you're re-introducing foods you could give them a try. they might be more easily tolerated than cow's milk, but it's really individual so you would just need to experiment. :) 

Niki Bezzant says:

Hi Elizabeth - because the science on FODMAPs is new and developing, the lists of foods are changing a bit. I suggest the Monash University FODMAP app if you have a smartphone - it's very very useful. According to that: broad beans are high in fructose, so if that is a problematic FODMAP for you, broad beans are not good. If you are OK with fructose then you should be fine. Beetroot is OK in small doses (2 slices or less). says:

I have been on the low FODMAP diet for over two weeks but am still at time having to spend sessions of 20-30 mins on the toilet If start to bring foods back into my diet after a month or so. how will I know if they are a problem?

Niki Bezzant says:

Embarking on a low-fodmap diet on your own is pretty tricky - I'd strongly advise seeing a dieitian who specialises in this area if you're having problems - the issue could be another food chemical or it could be something else entirely. (ie FODMAPs might not be the answer for you).  If it is, chances are you need to be on a full elimination phase for more than two weeks - it can take a while for things to settle down if your IBS has been quite bad. But getting professional help is highly recommended. -Niki

Tracey Plummer says:

Hi there,
I am starting the FODMAP diet tomorrow as suggested by a gastroenterologist (yippee ... NOT). Anyway, I absolutely love raspberry jelly and have it most nights, I'm pretty sure it's ok but just wanted to check if you can confirm either way for me.
Thanks in anticipation.

Niki Bezzant says:

Hi Tracey - I actually can't find anything in the FODMAPs data about fruit jellies. Fruit juices can be problematic - some are high in fructose - but raspberries in their fresh state are OK. Short answer - I would be careful, and see how it goes! - Niki

Wilma Duncan says:

Tracey - you might like to try banana icecream with raspberries. You can make the icecream in a foodprocessor. I use a Yonanas machine. You peel and chop a banana, freeze for 24 hours (or less). Put half the frozen banana through the machine and add raspberries then the remaining banana. It comes out like soft icecream - delicious.

Wilma Duncan says:

I make banana icecream with frozen raspberries. Both the banana and raspberries are frozen. Would it be safe to make the icecream and freeze it?

Hi Niki, after being gluten free for about a year, I've started having problems again, with high flatulence (embarrassing) and being bound up. My doctor has suggested that I go on a FODMAP diet. should I use a dietian for this.

Healthy Food Guide says:

Hi Sally - apologies for the delay in responding to your comment. Yes, we do recommend you use a dietitian to help guide you through a FODMAP diet as it can be a reasonably complex exercise. Good luck with your journey, and we hope it provides you with some respite from your symptoms.

I am getting no support from my doctor and only just encountered FODMAP. I have self diagnosed myself with an intolerance to potato and corn / maize. It appears that I can eat wheat and dairy, but when trying to eliminate potato and corn from my diet it is proving difficult as a lot of products are switching from wheat to potato or maize for those that are gluten free. Is this intolerance (bloating, cramps, gas and if I consume enough diarrhea ) to potato and maize FODMAP?

Niki Bezzant says:

Hi Hine. It seems unlikely that you have a FODMAP issue - but I think you would really benefit from seeing a dietitian with expertise in the area of IBS. Self-diagnosis can often miss the bigger picture of what is really going on, and with FODMAPs there is a bigger picture. For example - potatoes are not a FODMAP food, so if your issue is FODMAP-related, potatoes should not cause a problem at all. Corn (ie sweetcorn) is a FODMAP-containing food, but even so, small amounts (eg 1/2 cob of corn) and some corn products such as polenta (cornmeal) should also be tolerated. So there could very well be something else going on here, which a dietitian could help you figure out. It's tough going doing it alone! 

Niki Bezzant says:

I'm not sure on the yoghurt - perhaps check one of the bigger, better supermarkets or specialty stores like IE Produce. So Good is a soy milk made from soy protein which is what you want, not one made from whole soy beans. 

A question about coconut as I see no reference to it anywhere. I normally substitute coconut sugar for honey in recipes and as I am GF, its a common flour I use in baking. Is coconut in any form - desiccated, sugar, flour or milk/cream safe on low FODMAP?

Niki Bezzant says:

Coconut has some polyols, so use caution with it and its products (eg coconut water, coconut shredded, dried, dessciated etc). Small amounts should be OK. I can't find anything on coconut sugar, but we do know there's nothing particularly special about it and it's really expensive, so you'd be just as well to substitute brown or raw sugar for coconut sugar, and save a bit of money! And of course, use sparingly as you would all sugar. :) 

Hi, I can't get the link with the dietitians contact details to work. Can you confirm what the correct link is please?

Healthy Food Guide says:

Thanks for pointing that out to us, Mina - unfortunately it looks like IBSNZ is no longer operating. We've updated the link to take you to the HFG health practitoners directory, as many of the people listed there can help with FODMAP diets. Good luck with your search.

Low fodmap diet and Gluten free diet.
I have been on a low fodmap diet since December and a gluten free diet for round 3 weeks. I am still having some symptoms after trying both these, any ideas.

Niki Bezzant says:

I'd suggest you talk to a dietitian or nutritionist who specialises in IBS - there are lots around now. The low-FODMAP diet is complex, and there are some pitfalls you might not even realise you're falling into. Also, the problem for you could be something else - which an expert would be able to delve into. They'll also be able to help you get to a point where you're not avoiding foods unecessarily. 

Hi. Can onion pulp with a little onion juice be included in soups and casseroles for a person on a fodmap diet?
Secondly, can you give me hints on gluten and fodmap diets for a person who's lactating. Thank you

Niki Bezzant says:

Hi Elinor - it's unlikely onion pulp/onion juice would be suitable if fructans are a problem - which they often are. You'd be better off using the green part only of spring onions. 

mobr023 says:

I bought gluten free breadcrumbs but see they have onion in them.
Can I eat these breadcrumbs on a FODMAP diet?
Does that amount of onion matter?

Thank you

Niki Bezzant says:

If it's a tiny bit of onion powder, it's proably going to be fine. Try it and see. If it's whole onion pieces that might be more of a problem. As always, it's the total load that's the issue. :) 

I eliminated all wheat and dairy at doctor's suggestion 6 months ago, now use almond milk in tea and coffee - symptoms have returned and I now realize that the almond milk may be one of the culprits - help - what now? Don't use soy products as I don't fully trust their credentials! I also use nuts as a healthy snack - any suggestions on alternatives please? thank you

Niki Bezzant says:

Soy milk made from soy protein is low-FODMAP, so I'd suggest that as an alternative. So Good is a brand made with soy protein. Avoid soy milk made from whole soy beans (odd I know, but sometimes the degree of processing seems to affect the FODMAP content). Nuts vary - have you got the Monash University FODMAP app? It's very useful for telling you what's suitable, and in what doses. Almonds are OK in small doses (10 nuts or less) so it could be if you're having a lot of almond milk that might have an effect. FODMAP friendly nuts are macadamia, walnuts, pecans, pine nuts, peanuts. Also most seeds are fine, too, and make nutritious snacks. :) 

Hi I Have Gastroparies and reflux I had mic butten tube for seven years a couple of years ago I had the tube removed because of infections the site did not by itself so had it intenaly closed.since then I havn't been well againso today I went back to to Docter she said that had iratable bowel sundrome gave me a link to the website to have a look at.not sure where to start what I should elimiute first.
Thanks Debbie Kane

Niki Bezzant says:

Hi Debbie - I think the best thing for you would be to see a dietitian who specialises in IBS and gut issues - you will need very specific help. Your doctor should be able to organise a referral. 

Hi I have had problems with bloat, constipation for a while. I feel I eat a very healthy diet and have eliminated wheat and dairy from my diet. I take probiotics, digestive enzymes and make my own water keffir and sauerkrat. At present nothing much seems to help as during the course of the day and especially after dinner my tummy is hugely distended and very uncomfortable. I eat salad every night will steamed veges and wondering if the salad greens are the culprit. I eat red meat about once a month as I feel this just bungs me up. My doctor suggested the fodmap diet but upon reviewing it it says lettuce is ok, any suggestions as I'm going crazy !,,,

Niki Bezzant says:

Hi - the issue could easily be FODMAPs - they are in lots of very healthy foods. It's impossible to say what the issue maybe for you, but it could be the other veges in your dinner, or anything you've eaten in the day, or most likely a combination of things. It would be ideal to consult a dietitian who specialises in IBS, who could guide you through a FODMAP elimination and re-introduction. There's a protocol for this so that you can actually identify the problem FODMAP groups for you. Good luck! 

whalleyworks@xn... says:

Geraldine. Hi there, plese could you tell me if sauerkrat is ok? And also, are any of the dried fruits ok on a fodmap free diet? Thanks.

Niki Bezzant says:

Cabbage is generally OK in reasonable servings (1 cup or less). If there's garlic or onion in your sauerkraut you could run into problems if fructans are an issue for you. With dried fruit, they will be OK if fructans are not an issue. If fructans are an issue, then dried fruit in any larger serving sizes will be a problem. Dried cranberries in a serving size of 1 tablespoon or less should be fine. :)