What is the Low FODMAP Diet?
The Low FODMAP Diet was designed by a team of researchers at Monash University to help reduce gastrointestinal (gut) symptoms such as bloating, abdominal pain, constipation, and diarrhoea in patients with medically-diagnosed Irritable Bowel Syndrome (IBS).
The Low FODMAP Diet is currently the most effective dietary intervention available for patients with IBS, and has been shown to significantly improve symptoms in 3 in 4 people (1).
What is IBS?
IBS is a very common functional gastrointestinal disorder, affecting around 1 in 7 Australian adults. In fact, it is the most frequently diagnosed condition by gastroenterologists in Australia (2).
The formal criteria for a diagnosis (as per the Rome Foundation (3)) are:
Recurrent abdominal pain on average at least one day per week in the last three months, and is associated with two or more of the following:
1. Related to defaecation (i.e. the abdominal pain can be better or worse after having a bowel movement); and/or
2. Associated with a change in frequency of stool (i.e. passing a bowel movement more or less frequently); and/or
3. Associated with a change in form (i.e. the appearance) of stool
The importance of seeking a definitive diagnosis of IBS
If you are experiencing frequent bouts of abdominal pain, bloating, constipation and/or diarrhoea, the first step is to have blood test through your GP to rule out Coeliac Disease as a potential cause of your symptoms, as the gut symptoms of untreated Coeliac Disease are often mistaken for IBS. Because Coeliac Disease is both relatively common in Australia (approximately 1 in 70 people (4)), and has serious health consequences if left untreated, it’s incredibly important to rule it out as a potential cause of your symptoms. There are two different blood tests requested by GPs to screen patients for Coeliac Disease: an antibody test (the most common, which requires you to be eating gluten daily), and a genetic test, which looks at your genetic susceptibility to developing Coeliac Disease in your lifetime.
Once you have had Coeliac Disease ruled out as a potential cause of your symptoms, the next step is to speak to your GP and/or a gastroenterologist about ruling out other conditions which can mimic the symptoms of IBS, such as Inflammatory Bowel Disease. This may require further blood tests and/or stool tests.
What are dietary FODMAPs?
FODMAPs is an acronym which describes a collection of short-chain carbohydrates (sugars) that are only partially-absorbed in the small intestine, and can be fermented by the resident bacteria in the large intestine. These bacteria produce gases (such as hydrogen and methane) which can cause wind, abdominal bloating, and/or constipation, triggering the sensation of pain in patients with IBS, due to hypersensitivity of the nerve endings found in the gut (known as visceral hypersensitivity). The presence of the dietary FODMAPs in the large bowel can also cause water to enter the bowel, resulting in diarrhoea.
The Low FODMAP Diet Basics
The Low FODMAP Diet is not a 'forever' diet; it is a restrictive elimination diet employed by dietitians to determine whether your usual intake of dietary FODMAPs is triggering your IBS symptoms, achieved by significantly reducing the total load of FODMAPs in your diet for a period of two to six weeks.
If the diet results in a significant improvement in your symptoms, you will be guided through the re-challenge phase (the second phase of the diet), which seeks to determine your individual tolerance to each of the FODMAPs (5).
Why not just stay on a low FODMAP diet indefinitely if it relieves the symptoms of IBS?
The FODMAPs are actually a source of fuel for the good gut bacteria (the bifidobateria and lactobacilli), which produce a wide range of compounds (such as short-chain fatty acids) with well-defined health benefits. As such, the ideal diet for keeping the gut healthy should be high in FODMAPs, not low in FODMAPs.
What does FODMAPs stand for?
FODMAPs refers to Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols, which is quite a mouthful - thankfully we have such a catchy acronym!
The FODMAPs are categorised as:
Oligosaccharides, which includes:
Fructans (also known as fructo-oligosaccharides, or FOS): found in foods such as wheat, rye, garlic and onion; and
- Galactans (also known as galacto-oligosaccharides, or GOS): found in legumes (beans, peas, chickpeas and lentils)
Disaccharides – this refers to the disaccharide lactose, which is of no relevance to vegans, as it is only found in dairy products
Monosaccharides – this refers to foods which contain fructose in excess of glucose, such as apples and pears
Polyols – these are a very common cause of bloating and wind. They are found naturally in certain fruits and vegetables, but also in sugar-free chewing gum, mints, lollies and chocolate. Examples of polyols in plant foods are:
- Sorbitol - found in apples and stone fruit (such as apricots, nectarines and peaches)
- Mannitol - found in celery and mushrooms
Is the low FODMAP diet suitable for vegans?
As the FODMAPs are found almost exclusively in plant foods (with the exception of lactose in dairy products), the low FODMAP diet is particularly restrictive (although not impossible!) for vegans.
What Can Vegans Eat On A Low FODMAP Diet?
Examples of suitable low FODMAP foods for vegans are:
Non-dairy milks: almond milk, soy milk (made from soy protein), rice milk
Fruits: unripe (slightly green) bananas, strawberries, oranges, kiwi fruit, grapes, mandarins, cantaloupe, honeydew melon, passionfruit, paw paw, raspberries, blueberries, pineapple
Vegetables: potato, carrot, zucchini, capsicum, kale, green beans, eggplant, tomato, cucumber, bok choy, ginger, parsnip, radish, silverbeet, baby spinach, Swiss chard, green cabbage, celeriac, squash, chives, choy sum, endive, lettuce, turnip, Chinese Cabbage, Jap (Kent) pumpkin
Nuts & Seeds: Brazil nuts, pumpkin seeds, sunflower seeds, chia seeds, sesame seeds, flaxseeds, peanuts, macadamias, pecans, walnuts, pine nuts
Legume foods: firm tofu, tempeh, up to 1/2 cup tinned red kidney beans (6), up to 1/2 cup tinned brown lentils
Grains: quinoa, brown rice, oats, millet, bean thread noodles, polenta
Grain products: spelt sourdough bread, gluten-free bread, buckwheat pasta, gluten-free pasta (made from gluten-free ingredients such as rice, potato and corn)
Condiments: lemon juice, fresh herbs, dried spices, tamari, soy sauce, vinegars, coconut milk, maple syrup
Drinks: green tea, white tea, black tea, cacao powder, peppermint tea
Low FODMAP Vegan Meal Ideas:
- Porridge made with 1/2 cup rolled oats or quinoa with chia, unripe banana, strawberries and low FODMAP non-dairy milk of choice
- Spelt sourdough toast with peanut butter and sliced unripe banana
- Gluten-free Weet-Bix with low FODMAP non-dairy milk of choice and low FODMAP fruit
- Spelt sourdough toast with scrambled firm tofu (with added low FODMAP vegetables, e.g. baby spinach and tomato)
- Warm brown rice pudding with low FODMAP non-dairy milk of choice and cinnamon
- Berry or unripe banana smoothie with low FODMAP non-dairy milk of choice and chia seeds
Main Meal Ideas:
- Rice paper rolls with grilled tofu, rice noodles, carrot, cucumber, coriander and capsicum with a homemade low FODMAP peanut butter and lime juice dressing
- Sushi with brown rice, tamari marinated tofu, capsicum, cucumber and carrot
- Buckwheat or gluten-free pasta with tinned diced tomatoes (up to 1/2 cup per serve) and low FODMAP vegetables (e.g. grated zucchini, carrot, baby spinach) and either crumbled tofu or 1/2 cup tinned brown lentils/red kidney beans
- Fried brown rice or quinoa with tamari-marinated tofu, chives, diced carrot, diced zucchini and spinach
- Tofu and low FODMAP vegetable stir-fry (e.g. green beans, capsicum, bok choy, carrot, zucchini) with homemade peanut satay dressing
- Grilled marinated tofu or tempeh (in a tamari, ginger, orange juice and maple syrup marinade), served with brown rice or quinoa and steamed low FODMAP vegetables
- A serve of low FODMAP fruit
- A handful of low FODMAP nuts, e.g. walnuts
- A slice of spelt sourdough toast with peanut butter
- A smoothie with berries or banana, chia and low FODMAP non-dairy milk of choice
Nutrition Tips for Vegans on a Low FODMAP Diet:
Even though the diet is only short-term, it is still important to ensure you are meeting your nutrient requirements.
My nutrition tips for vegans are:
- Include a serving of either firm tofu (150g), tempeh (100g) or allowed legumes (1/2 cup tinned red kidney beans or brown lentils) with at least two meals per day to ensure you are meeting your requirements for protein, iron and zinc
- Include at least 2 servings of low FODMAPs fruits and 5 servings of low FODMAPs vegetables daily
- To meet the Recommended Dietary Intake for calcium (1000mg for adults between 19 and 50 years), choose non-dairy (soy or almond) milks fortified with at least 300mg calcium per cup, tofu set with calcium salts (listed as ‘E509/E516 on the ingredients list), and calcium-rich vegetables such as bok choy and Chinese cabbage every day
- Don’t forget to supplement with vitamin B12, use iodised salt (or take a daily multivitamin, which generally provide 100% of the RDI for iodine), and consider an algal-derived EPA + DHA omega-3 supplement
Is the low FODMAP diet a gluten-free diet?
No, the low FODMAP diet isn’t strictly gluten-free, but it is a mostly wheat-free diet, as wheat is naturally high in FOS. Some gluten-containing foods are allowed on the diet, including rolled oats and spelt sourdough bread. Spelt is a variety of wheat which is naturally lower in FOS than regular wheat or rye, and the FOS content is further reduced by the traditional sourdough fermentation process employed in breadmaking. Only spelt sourdough bread can be included in the diet - not spelt pasta, rolled spelt, or other spelt products.
Should I try probiotics for IBS?
There is some evidence to suggest that probiotic supplementation may be beneficial for people with IBS (7), but Monash University recommend trialling one intervention at a time (i.e. either the Low FODMAP diet or probiotics), so you know what is most beneficial for you.
I can't tolerate any amount of legumes in my diet. What should I do?
The FODMAPs found in legumes (galacto-oligosaccharides or GOS) are unable to be digested by humans, as our bodies don't produce the required enzyme (α-galactosidase) to cleave a specific bond found in between the sugar subunits in these carbohydrates. As such, GOS are known as prebiotic fibres, as they pass through the digestive tract to the large intestine, where they are fermented preferentially by the good gut bacteria (lactobacilii and bifidobacteria).
For people transitioning to vegan diets, the rapid increase in consumption GOS-containing legumes can cause abdominal bloating and wind, however, this usually resolves with regular consumption, as the gut bacteria adapt to breaking down the GOS more efficiently.
One study investigating the increase in flatulence with regular legume consumption (1/2 cup cooked beans per day) found that although one third of participants reported an increase in flatulence by the end of the first week, only 3% were still experiencing significant flatulence by the end of the eight week study (8). Similar findings were found for bloating, with 13% of participants reporting an increase in bloating at the end of the first week, which dropped to only 2% of participants by the end of the study (8).
My advice for vegans who struggle to eat legumes is to include a small amount every single day (or on alternate days if symptoms are severe), alternating legumes with tofu or tempeh at main meals. This may be as little as a tablespoon of homemade hummus (without added garlic) or 1/4 cup cooked legumes with just one meal per day. Including the legumes regularly is imperative to encouraging your gut bacteria to break down the GOS more efficiently.
If you are still struggling with including legumes regularly, a recent study published by researchers at Monash University showed that their may be a benefit to trialling an 300mg α-galactosidase supplement with legume meals (9), which can be purchased online from retailers such as iHerb.com.
What if I my symptoms don't improve on the Low FODMAP Diet?
If you're one of the one in four people with IBS who doesn't experience a significant improvement in your symptoms with the Low FODMAP Diet - don't despair! - there are a number of alternative interventions that may help, such as gut-directed hypnotherapy (practised at the Mind+Gut clinic here in Melbourne), probiotics, medications, or clinically-trialed herbal preparations (such as Iberogast).
Resources for patients with IBS:
I recommend trialing the Low FODMAP Diet under the guidance of an Accredited Practising Dietitian (APD). You can find a local dietitian using the Find an APD search function on the Dietitians Association of Australia website. Select ‘gastrointestinal (bowel and stomach) disorders’ in the area of practice dropdown menu to find a dietitian familiar with the Low FODMAP Diet.
I also recommend purchasing the Monash University Low FODMAP Diet app (available for iPhone and Android) if you are considering trialling the diet. It contains a comprehensive searchable food guide, which makes shopping while on the diet a breeze.
1. Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome. Gastroenterology. 2014 Jan;146(1):67–75.e5.
2. Marsh A, Eslick EM, Eslick GD. Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis. Eur J Nutr. 2016 Apr;55(3):897–906.
3. Schmulson MJ, Drossman DA. What Is New in Rome IV. J Neurogastroenterol Motil. 2017 Apr 30;23(2):151–63.
4. Coeliac Disease - Coeliac Australia [Internet]. [cited 2018 Feb 28]. Available from: https://www.coeliac.org.au/coeliac-disease/
5. Tuck C, Barrett J. Re-challenging FODMAPs: the low FODMAP diet phase two: Re-challenging FODMAPs. J Gastroenterol Hepatol. 2017 Mar;32:11–5.
6. Tuck C, Ly E, Bogatyrev A, Costetsou I, Gibson P, Barrett J, et al. Fermentable short chain carbohydrate (FODMAP) content of common plant-based foods and processed foods suitable for vegetarian- and vegan-based eating patterns. J Hum Nutr Diet [Internet]. 2018 Feb 23 [cited 2018 Feb 26]; Available from: http://doi.wiley.com/10.1111/jhn.12546
7. McKenzie YA, Thompson J, Gulia P, Lomer MCE, (IBS Dietetic Guideline Review Group on behalf of Gastroenterology Specialist Group of the British Dietetic Association). British Dietetic Association systematic review of systematic reviews and evidence-based practice guidelines for the use of probiotics in the management of irritable bowel syndrome in adults (2016 update). Journal of Human Nutrition and Dietetics. 2016 Oct;29(5):576–92.
8. Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutrition Journal. 2011 Dec;10(1):128.
9. Tuck CJ, Taylor KM, Barrett JS, Gibson PR, Muir JG. Oral α-galactosidase improves gastrointestinal tolerance to a diet high in prebiotic fibre (galacto-oligosaccharides). Journal of Nutrition and Intermediary Metabolism. 2017 Jun;8:71