Figuring out what you can eat, what you can't eat and then navigating the supermarket can all be overwhelming when starting the low FODMAP diet. This guide will talk you through what the elimination or restriction phase of the low FODMAP diet is and answer your questions to help you get symptom free faster.
Before You Start
Before you dive head first into the low FODMAP diet, it is important that you stop and go and see your doctor and if possible a low FODMAP trained dietitian. The low FODMAP diet is a medical nutritional therapy commonly used to help people with IBS control their symptoms. It's restrictive and can be socially awkward so the diet isn't the best option for everyone. Also your doctor needs to rule out that your troubling GI symptoms are not being caused by other serious medical conditions like coeliac (celiac) disease, inflammatory bowel disease, Crohn’s disease, cancer or other medical conditions (1 2). Once you are on the low FODMAP diet, testing for some of these medical conditions can become more challenging.
If possible, a registered dietitian with specialised knowledge of the low FODMAP diet can you help navigate the complexity of the diet while making sure you are get the nutritional requirements that your body needs (2c). Your dietitian will also help you troubleshoot if your symptoms aren't settling, before walking you through re-challenging and reintroducing high FODMAP food back into your diet.
What the heck is FODMAP?
If you are sitting there thinking FOD-what? Then you aren't the only one... No FODMAP isn't an acronym out of a sci-fi movie, nor is it the latest and greatest new candy flavour. In super simple terms FODMAPs are short chain carbohydrates (sugars). Don't panic - the diet isn't actually sugar free and you can still enjoy a low FODMAP treat! These FODMAPs naturally occur in a wide range of fruit, vegetables, cereals, grains, dairy products, legumes and pulses. The FODMAPs are poorly absorbed in our small intestines where they draw water into our bowels. Next the FODMAPs are fermented by our gut bacteria in our large intestines where they create gas, which triggers unpleasant GI symptoms.
Let's break the FODMAP acronym down:
This nasty sounding FODMAP group isn't as scary when you break it down into it's sub groups: fructans and galactans. Fructans (fructo-oligosaccharides or FOS) are commonly found in onion, garlic, wheat, rye, barley and dried fruit. Galactans (galacto-oligosaccharides or GOS) are often found in silken tofu, pistachios, cashews, legumes and pulses (7 8).
Have you ever wonder why beans make everyone fart? This is because humans weren't born with the right enzymes to fully digest oligosaccharides, so they will make everyone gassy but only trigger IBS symptoms in some people (2 8).
The only disaccharide you need to worry about is lactose which can be found in products derived from cow, sheep or goat's milk. Lactose contains two sugar units that need to be 'unzipped' using an enzyme called lactase before our bodies can absorb it. If your gut lacks lactase enzymes then you will struggle to process high lactose products and they are likely to trigger symptoms.
This is simply fructose that is found in excess of glucose. To process fructose effectively our bodies need equal amounts of glucose to stop it being malabsorbed. This means on the low FODMAP diet we only worry about foods containing excess fructose like apples, pears, mango, honey, asparagus, and high fructose corn syrup.
Polyols are sugar alcohols but they won't make you drunk. They are found in a wide range of fruit (apples, pears, stone fruit, lychee) and vegetables (mushrooms, cauliflower, sweet potato). They are also man-made and used in products as low calories artificial sweeteners like protein powders, chewing gum, and diabetic candy.
What is the Elimination Phase?
The low FODMAP diet is broken down into three phases: elimination, reintroduction, and then modified low FODMAP diet. The elimination or restriction phase is the initial phase of the diet where the goal is to significantly reduce or completely resolve your IBS symptoms through lowering the amount of FODMAPs you eat (5). To achieve this we need you to remove all high FODMAP foods from your diet and focus on eating low FODMAP foods instead.
It is recommended that you only stay in the elimination phase for a 2 to 8 week period while you gain symptom control (6, 7, 8). Due to the complexity of the low FODMAP diet, a 2 week elimination period is sometimes not long enough, as it can a few weeks before you stop accidentally consuming high FODMAP foods. Once your symptoms are under control you can then start the reintroduction phase with the guidance of your dietitian.
Where do you find low FODMAP food lists & serving size information?
If you are working with a dietitan then they will normally provide you with a list of high and low FODMAP foods. Otherwise the Monash University FODMAP App or FODMAP Friendly App are great resources and have up-to-date lists of high and low FODMAP Foods.
The Monash app clearly indicates high and low FODMAP foods through a traffic light system, and gives safe serving sizes for each food (2). Their system works by rating foods as green (low FODMAP dose), orange (moderate FODMAP dose), and red (high FODMAP dose) (5). Monash University also produces a printed guide, The Monash University Low FODMAP Diet booklet.
The FODMAP Friendly app has a pass/fail system for each food which shows their FODMAP rating. You can also look at the FODMAP percentages for each food to see if the FODMAPs compound when you eat different foods together.
When undertaking the elimination phase, Monash University researchers recommend that you avoid the red foods/portion sizes, limit the orange foods/portion sizes, and eat mainly the green rated foods/portion sizes (5). You can eat a number of green rated (low FODMAP) foods per meal, however it is important that check the suggested serving sizes, as some foods become high FODMAP in larger serves (5). You will find more information on the importance of serving sizes here.
Where do sneaky FODMAPs hide?
FODMAPs love to hide in processed products and many pre-made products and sauces contain high FODMAP ingredients. Look out for high FODMAP fruits/vegetables (particularly onions and garlic), high fructose corn syrup (HFCS), inulin, honey, and wheat (2 3). During the elimination phase it is recommended that you avoid high FODMAP ingredients if possible. When it comes to wheat, rye, and barley try to avoid products that list these ingredients as first to third in the ingredient list (3). For more information on how to read labels please read our Low FODMAP Guide To Reading Labels.
Is gluten a problem while on the low FODMAP diet?
There is often a lot of confusion around this point. Gluten is a protein and FODMAPs are carbohydrates. This means gluten does not need to be avoided, however gluten free products are often recommended while on the diet. This is because wheat, rye and barley which contain gluten also contain oligosaccharides so eating gluten free helps you avoid these FODMAP sources. The goal is to limit the oligosaccharides and not the gluten (7). Small amounts of wheat can be low FODMAP and should not be a problem unless you also have coeliac disease. Not all gluten free products are FODMAP friendly as they can contain sneaky FODMAPs.
Are alcohol & caffeine allowed during the elimination phase?
While on the low FODMAP elimination phase it is often recommended that you limit your consumption of alcohol and caffeine (2 1). While small amounts of caffeine and most alcohols are not high in FODMAPs, they can be gut irritants and can make IBS symptoms worse (2 1). This means you should test alcohol and caffeine in the reintroduction phase of the low FODMAP diet after talking to your dietitian.
How do you deal with constipation on the low FODMAP diet?
The low FODMAP diet is lower in fibre which can be problematic for some people and cause constipation. This means you may need to increase low FODMAP fibre rich foods and your water intake (2). If you are struggling with constipation after starting the low FODMAP diet make sure you consult with your dietitian.
Do you need to keep a food diary?
If your symptoms are start settling quickly while on the elimination phase, then there is often no need to keep a food diary. However, if you are still having unexplained symptoms then a food diary can help identify low FODMAP foods that are IBS triggers for you. Talk to your dietitian about the best way to keep a food diary so they can help you identify problem foods.
When do you test high FODMAP foods?
Are A Little Bit Yummy’s recipes safe for the elimination phase?
A Little Bit Yummy’s recipes are based on the Monash Low FODMAP App serving size guidelines and have been checked by low FODMAP trained registered dietitian. This means the recipes are safe to use as a resource during the elimination phase.