Blog Post

The Low FODMAP Diet: Everything You Need to Know

Low FODMAP diet title banner

Do you suffer from chronic bloating, abdominal pain and altered bowel habits?

If yes, then it’s likely you’ll benefit from the Low FODMAP diet.

Many GP’s and health practitioners are regarding it to be one of the best investigative diets for identifying problematic foods. Research shows that people with Irritable Bowel Syndrome (IBS) can often significantly improve symptoms by managing the amount of FODMAPs in their diet.

The success rate in terms of significantly improving symptoms is around 50-86% depending on the research you are looking at.

This post covers what FODMAPs are, how to follow the low FODMAP diet, and the importance of methodically reintroducing FODMAP foods into your diet below.

What Are FODMAPs?

FODMAPs are a group of food compounds that are eliminated on the low FODMAP diet. The low FODMAP diet, created by Sue Shepherd and her team in Melbourne, Australia, is a temporary elimination diet that aims to reduce symptoms of IBS.

The acronym FODMAP stands for:

Fermentable – these types of compounds are broken down (fermented) by bacteria in the large intestine
Oligosaccharides – “oligo” means “few” and “saccharide” means sugar. These molecules are made up of individual sugars joined together in a chain
Disaccharides – “di” means two. This is a double sugar molecule
Monosaccharides – “mono” means single. This is a single sugar molecule
● And Polyols – these are naturally occurring and manmade sugar alcohols

All FODMAPs are short-chain carbohydrates that ferment in your large bowel if they’re poorly digested. This results in many common symptoms of IBS including bloating, pain, and abdominal distention. As the fermentation process draws in water and produces carbon dioxide, hydrogen, and/or methane gas.

List of FODMAP-Containing Foods

There are 5 overarching types of FODMAPs found in a variety of different foods. They include:

Fructose: A natural sugar found in most fruits and some vegetables. Fructose containing foods are typically only high FODMAP when fructose is in excess of glucose.
Lactose: A natural sugar found in dairy foods like milk, yoghurt and some cheeses.
Fructans: Found in many vegetables and grains.
Galactans: Found primarily in legumes and beans.
Polyols: Sugar alcohols like xylitol, sorbitol, maltitol and mannitol. Commonly found in chewing gum or “no sugar” food and drinks.

The above FODMAPs can be found in high quantities in a variety of foods including:
Vegetables: artichoke, garlic, onion, asparagus, cauliflower, leek, mushrooms, sugar snap peas
Fruits: mango, apples, blackberries, cherries, figs, grapefruit, nectarine, peach, pear, plum and watermelon
Grains and Cereals: wheat, pumpernickel, kamut, rye, barley, spelt, and wheat noodles.
Dairy: cream cheese, sour cream, custard, ice cream, cow’s milk, and yoghurt.
Legumes, Nuts & Seeds: cashews, pistachios, baked beans, black beans, broad beans, chickpeas, fava beans, split peas.
Added Ingredients & Sweeteners: inulin (chicory root), natural flavours, high fructose corn syrup, agave, honey.

Be sure to read the ingredients list on the nutrition label of each product for any FODMAPs, including those added ingredients.

Is The Low FODMAP Diet Gluten Free?

There is a degree of overlap between the low FODMAP diet and a gluten-free diet.

This is because fructans are found in wheat (amongst other things).

During the elimination phase, you limit your wheat intake. Since the main source of gluten in most peoples diets is wheat, this leads to a significant reduction in gluten intake.

A low FODMAP diet is not specifically a gluten-free diet. For those with coeliac disease, gluten needs to be completely avoided.

On a low-FODMAP diet, fructans just need to be kept to a low amount during the elimination phase. After that phase, individual tolerance is assessed.

As an interesting note though, it seems like fructans account for the vast majority of IBS symptoms that are reportedly linked with non-coeliac gluten sensitivity.

Fructans vs Gluten

How to Know What Foods are Low FODMAP

One of the difficulties of the diet is identifying which foods and ingredients are or are not low FODMAP.

The easiest way to check and see what the FODMAP content of foods are is to check out our comprehensive FODMAP food list resource. There is also a PDF version in there which you can use to search foods if you are ever in doubt.

Shown below is a helpful but less comprehensive list of foods to use as a starting point.

List of low fodmap foods
List of high fodmap foods

And although I have kept it simple in terms of explaining it as though a food either is or is not low FODMAP, it actually is slightly more complex than that. It is based on the amount of that food. An individual food can be low FODMAP in a small serving size, but high FODMAP in a larger serving size.

The Elimination Phase

This strict phase of the Low FODMAP diet is not a long-term solution. It’s an elimination phase only.

The Low FODMAP diet should be followed for 2-6 weeks, depending on how you respond. All FODMAPs are strictly limited within your diet in order to see a reduction in symptoms.

If and when the diet has successfully reduced your symptoms, you may then move into the next phase of the diet.

The Reintroduction Phase

During this phase you begin methodically reintroducing each FODMAP type one at a time, to determine which ones trigger your symptoms. For example: reintroduce a fructose only containing food such as fruit, followed by a FODMAP-free “washout” period, before trying a different FODMAP type.

FODMAPs often have a dose-dependent relationship with symptoms, so varying amounts of each food should be tested – remember the goal of the diet is to help ensure you are not unnecessarily eliminating beneficial foods from your diet.

If you have no symptoms from one type of FODMAP at a certain amount, this food can be trialled in higher amounts. If after one week of including the food in your diet with no symptoms, then that food is safe for you to eat.

If symptoms arise, you should end the trial of that FODMAP type and return to a baseline low FODMAP diet until symptoms settle/at least 3 days. Record how much, if any of that food you are able to eat before getting symptoms. You can try the same food at a lower dose if you think you have started too high, or you can move on to trying the next type of FODMAP.

Sometimes you might not be able to eat 1/2 an avocado, but 1/4 might be fine.

If you have no symptoms after reintroducing a FODMAP type, it’s important to still have the 3-day baseline low FODMAP diet break between trialling another type, as symptoms can occur days after consumption.

The initial reintroduction phase is complete once you have tried all 5 main types of FODMAPs. However, the aim is to reintroduce as much variety as possible, so if symptoms returned for one or more FODMAP types, you can also trial individual foods within the FODMAP types to assess your tolerance levels of those individual foods.

The process of trialling individual foods is the same as the original reintroduction phase. Once you have identified your problem FODMAPs, you can continue to limit or eliminate those foods to manage your symptoms long term.

How to Reintroduce FODMAPs

Reintroducing FODMAPs doesn’t have to be complicated. You should aim to do it in the comfort of your home, where you can control what you eat (and be close to amenities if required).

For those who would prefer to watch instead of reading, this video below is a great summary of how to implement the reintroduction phase.

Each individual FODMAP group should be tested using a food that is solely high in one FODMAP type. If you use a food that is high in two or more FODMAP types, then you won’t know which is causing your symptoms.

You can either:
A) Reintroduce a FODMAP food by consuming it at the same time you eat a regular low FODMAP meal i.e. a teaspoon of the FODMAP at the same time you eat your dinner OR
B) Combine the FODMAP food into your meal or snack i.e. soup or salad.

Option A allows you to easily take note of the portion size you consumed so that you can easily increase the amount during testing. Option B allows you to enjoy the food as part of your regular meal but makes it a little more difficult to know how much you consumed.

Below is the ideal test schedule for all FODMAP groups except for fructans & galactans:

Guide to the reintroduction phase of the low fodmap diet

Fructans and galactans pass through the digestive system more slowly and therefore take longer to trigger a reaction.

Due to this, these FODMAP groups require a slightly different testing schedule.

How to reintroducing fructans and GOS on the low fodmap diet

Now that you know how to test FODMAP groups, you will need to know what foods to use in order to do the testing.

FODMAP Challenge Phases
FODMAP Challenge Phases

There is no right or wrong time to test. It’s up to you, depending on when you can and the typical scenarios for when you would eat the food you’re testing. If you’re anxious about symptoms returning, do it in the evening when you’re home without any other commitments.

Stages of the low FODMAP diet

A Low FODMAP Meal Plan

A sample low FODMAP meal plan may look something like this:

Breakfast:

2 eggs
2 slices sourdough bread
1 small tomato
1 handful of baby spinach, sauteed in olive oil
1 small coffee with lactose-free milk

Snack:

1 mandarin
30g mix of walnuts, macadamia nuts and pecans

Lunch:

Tuna salad with potato, tuna, green beans, cherry tomatoes, olives, mustard and olive oil.

Snack:

1 banana
1 tbsp natural peanut butter

Dinner:

Chicken breast with brown rice, roast Jap pumpkin, carrot, potato, capsicum, broccoli, and zucchini.

Why the Low Fodmap Diet Isn’t a Permanent Solution

As the Low FODMAP diet is an elimination protocol and very restrictive in its nature, it’s important to highlight that the full diet should not be considered a permanent option. You do need to reintroduce foods at some stage, to allow for plenty of variety from a range of different food groups.

Emerging research shows eliminating FODMAPs over the long term can hinder your gut health and potentially cause more harm than good. It’s important to identify the FODMAPs that cause you symptoms, and in what amounts, so that you know how much you can tolerate, without having to avoid certain FODMAP foods completely.

It’s also important to reintroduce the FODMAPs back into your diet sooner rather than later to help decrease the chances of making your food intolerance worse.

Research on the Low FODMAP Diet

The Low FODMAP diet has been the main focus of research. In particular, its ability to help those with IBS.

IBS is a chronic disorder of the gastrointestinal system that results in symptoms including abdominal pain, bloating, excessive gas, diarrhoea and/or constipation. It is believed to affect 12–30% of people globally. Somewhere 70% of people with IBS respond well to the Low FODMAP diet.

It also seems to be far more effective for solving symptoms such as diarrhoea and bloating than constipation. That does not mean it cannot help with constipation, it just appears to have a much better success rate with other IBS symptoms.

The Low FODMAP diet is also effective in children, helping to decrease the frequency of abdominal pain.

Much more research is required to determine if the diet is an effective treatment for other conditions. However, according to the latest systematic review of the evidence, the Low FODMAP diet improves quality of life and reduces the severity of symptoms in those with IBS and should be considered as one of the go-to treatment options for this chronic digestive condition.

What if FODMAPs Does Not Work For You?

It is also worth highlighting that the low-FODMAP diet significantly helps in 50-86% of cases. That means not everybody finds benefit from it.

If the low FODMAP diet does not work for you, it is worth exploring other options such as the ones listed in this post on the topic.

How to Get Started

Normally I am not the kind of person to overtly promote myself or even dietitians in general. I much prefer trying to put out as much helpful content for free as I can, without being self-promotional. But when it comes to the low FODMAP diet, I highly recommend seeing a dietitian.

It is a difficult process to go through alone, although it certainly is possible. That being said, I’ve legitimately never seen somebody do the low FODMAP diet well on their own.

The way I would recommend going about it would be to either book in to see myself or my team or search through the Monash FODMAP dietitians directory to find another dietitian who specialises in this area.

By Aidan Muir

Aidan is a Brisbane based dietitian who prides himself on staying up-to-date with evidence-based approaches to dietetic intervention. He has long been fascinated by all things nutrition, particularly the effects of different dietary approaches on body composition and sports performance. Due to this passion, he has built up an extensive knowledge base and experience in multiple areas of nutrition and is able to help clients with a variety of conditions. One of Aidan’s main strengths is his ability to adapt plans based on the client's desires. By having such a thorough understanding of optimal nutrition for different situations he is able to develop detailed meal plans and guidance for clients that can contribute to improving the clients overall quality of life and performance. He offers services both in-person and online.