FODMAPs are by far one of the most interesting and helpful discoveries for the management of Irritable Bowel Syndrome (IBS) in recent years. If you’ve previously been diagnosed with IBS, or if you suffer from gastrointestinal distress on a regular basis, then a low FODMAP diet may be beneficial in helping you to manage your symptoms.

What is a low FODMAP diet and who is it for? | A Less Irritable Life


What are FODMAPs?

FODMAPs are fermentable oligosaccharides, disaccharide, monosaccharide and polyols. This is a technical term to describe small carbohydrate molecules, many of which are derived from natural sugars. However not all sugars and carbohydrates are FODMAPs – only specific ones. FODMAPs include excess fructose, lactose, fructans, galacto-oligosaccharides and sugar alcohols (e.g. mannitol, sorbitol, and some others).

What makes FODMAPs a problem is that they are fermentable. This means that when they are in the bowel, they can be fermented by bacteria to produce gas. FODMAPs also create an osmotic effect because they are sugars, meaning that they cause water to be pulled into the bowel. Together these effects can create bloating, excess gas and flatulence, diarrhoea and/or constipation.

While some FODMAPs are added to food during manufacturing, FODMAPs are also found in many natural foods that most people eat every day. For instance, the most commonly eaten FODMAPs are wheat, onions, garlic, legumes, apples and honey. The full list of foods that are high in FODMAPs is quite extensive so I won’t reproduce them here.


Are FODMAPs a problem for everyone?

While some FODMAPs are fermented in the bowel to produce gas in everyone, particularly the fructans and galacto-oligosaccharides, not everyone reacts to FODMAPs in the same way. People with IBS seem to be particularly sensitive to FODMAPs because IBS is associated with a visceral hypersensitivity, which means that the nerves in the gut of people with IBS react more strongly to the gas build up, causing an increased sensation of pain or discomfort in IBS sufferers.

Essentially that means that it’s people with IBS who will gain the most benefit from limiting the amount of FODMAPs that they eat each day. In fact, scientific research has found that about 75% of people who have IBS can obtain considerable relief in their symptoms if they follow a diet that restricts FODMAPs. This diet is known as the “low FODMAP diet”.


What is the low FODMAP diet and what is it’s purpose?

The first thing to understand about a low FODMAP diet is that it is a ‘low’ FODMAP diet and not a ‘no’ FODMAP diet. This means that the aim is to reduce the amount of FODMAPs that you eat, not eliminate them from your diet. Firstly, it’s next to impossible to remove all FODMAPs from your diet because they are present in many foods at varying amounts. Secondly, studies have shown that so long as the total amount of FODMAPs eaten across the day is very low, people can tolerate small amounts of FODMAPs in each meal provided that they do not exceed those thresholds.

The second thing to understand about a low FODMAP diet is that it’s purpose is to help you understand your own personal food intolerances. Because of that, the diet has three phases:

  1. An initial restriction phase that lowers all types of FODMAPs across your diet. This phase tests whether your IBS symptoms decrease on a low FODMAP diet, which will indicate whether FODMAPs are a trigger for your symptoms. Ideally, your symptoms will become little more than an irritation after this phase and you’ll find it much easier to go about your normal daily tasks without fear of IBS symptoms occurring.
  2. A reintroduction phase to test your tolerance to individual FODMAPs. This phase is to determine which FODMAPs specifically trigger your IBS symptoms, since most people with IBS can tolerate some of the FODMAPs, but not all of them. During this phase, you’ll test one type of FODMAP at a time by eating a food that is high in that one FODMAP, e.g. eating honey to test excess fructose. If you experience symptoms, you know this is a FODMAP that triggers your IBS symptoms. But if you don’t get symptoms, then it’s likely you’ll be able to eat other foods that contain that particular type of FODMAP.
  3. A maintenance phase where you adjust the low FODMAP diet to suit your needs. Once you know which FODMAPs you can tolerate, your diet is then adjusted to include these foods. The goal of this phase is to keep your IBS symptoms as manageable as possible, while allowing your food choices to be as varied as possible.

The third thing to understand about a low FODMAP diet is what it isn’t:

  • The low FODMAP diet is not a fad diet. The low FODMAP diet is a medical diet designed to help people who suffer from IBS. It has been extensively researched by scientists all around the world and continues to be researched today. It most definitely is not a fad diet. It does not restrict food groups unnecessarily and it is possible to maintain a healthy and balanced diet.
  • The low FODMAP diet is not a weight loss diet. The low FODMAP diet is not a calorie-restricted diet. It is not designed to help you lose weight. In fact, if you experience sudden weight loss when following a low FODMAP diet, you should see a qualified nutrition professional and/or your doctor to ensure that there isn’t something more sinister at play.
  • The low FODMAP diet is not a gluten-free diet. While the low FODMAP diet does require limiting gluten-containing grains because they are high in fructans, it is not the gluten in these grains that is the problem. For this reason, it’s possible to eat small amounts of gluten-containing grains while following a low FODMAP diet.
  • The low FODMAP diet is not a dairy-free diet. Lactose is a FODMAP that needs to be limited on a low FODMAP diet, however there are many lactose-free dairy products available that can be safely eaten by most people who need to limit lactose. Some people find that they enjoy using dairy-free alternatives instead of lactose-free dairy products, but unless you have an intolerance or allergy to dairy proteins (which is not a FODMAP issue), it is not necessary to eliminate dairy while following a low FODMAP diet.


Why would you choose to follow a low FODMAP diet?

A low FODMAP diet is not something that anyone would choose to follow for fun. It restricts specific food across all five of the food groups, which makes food choices difficult to navigate. This is particularly noticeable when it comes to processed foods or when you’re eating out and can’t control how your food is prepared. As such, the low FODMAP diet requires you to adapt your current food choices and favourite recipes to suit the foods that are low in FODMAPs.

That being said, a low FODMAP diet can be very effective for the management of IBS symptoms. While FODMAPs (or other food intolerances) don’t actually cause IBS, they have been shown to trigger IBS symptoms and create substantial pain or discomfort in 75% of sufferers. Therefore, if you suffer from IBS, following a low FODMAP diet could be a strategy to help make your life less irritable.


Is there anything you should do before starting a low FODMAP diet?

Gastrointestinal symptoms can be caused by many things, with IBS being only one of those things. Some causes are more of an inconvenience than a genuine risk to your ongoing physical health, such as IBS, although the ongoing challenges of IBS can greatly impact mental wellbeing in some people.

This is why you should always see a doctor if you’ve been experiencing ongoing gastrointestinal distress or if you’ve had recent changes in your bowel habits or the onset of persistent abdominal pain or discomfort. You should never try to diagnose your own symptoms because you could miss more serious issues and do yourself irreparable harm.

To help your doctor understand your gastrointestinal symptoms, it’s good to track them for at least a week beforehand to see if there are any patterns. Knowing what type of symptoms you experience and when you experience them will also help your doctor to make a more accurate diagnosis. The easiest way to do this is by using an IBS symptom tracker.

Once your doctor has ruled out other potential causes of your gastrointestinal symptoms, you should make an appointment to see a qualified nutritional professional who understands the low FODMAP diet and is up to date on the latest research.

Note that because of the complexity of the low FODMAP diet, and the diversity of the nutrition field, not all nutrition professionals will be able to provide you with the best information to help you so make sure you check their knowledge first.


What does following a low FODMAP diet involve?

The initial phase of the low FODMAP diet involves restricting foods that contain moderate to high levels of FODMAP so that your total intake of FODMAPs each day is kept very low. This requires you to completely avoid foods that are known to be very high in FODMAPs (which span all of the five food groups) and instead preferably choose foods that are known to be very low in FODMAPs.

In theory, this sounds like it wouldn’t be too hard if you had access to accurate lists of low FODMAP and high FODMAP foods. However, FODMAP levels aren’t quite that easy to control because there are also many foods that contain moderate levels of FODMAPs and so are only appropriate to eat if they’re consumed in safe portion sizes. Knowing these portion sizes is challenging, but the Monash University Low FODMAP Diet app does make it easier.

An additional complexity arises though because the amount of FODMAPs across each meal also has to be considered and FODMAPs can have additive effects. These challenges mean that people who try to follow a low FODMAP diet without support often make mistakes and don’t get the full benefit of the diet. When that happens, it can seem like the diet isn’t working, yet the lack of apparent benefits is really because it hasn’t been followed correctly.

This is why it’s best to trial the low FODMAP diet under the guidance of a qualified nutrition professional who specialises in FODMAPs. It’s also helpful if the person helping you has followed the diet themselves since they’ll understand what you’re experiencing and how challenging it really is to adjust your diet in the way that you need to. Believe me, I know how tough it is.

Another reason why it’s best to seek the assistance of a nutrition professional is that nutrient deficiencies can occur with these dietary restrictions. To make sure that this doesn’t happen, you need to get appropriate advice on how to adequately substitute ingredients to make sure that you are still eating a healthy and nutritionally balanced diet that is suitable for your personal needs.


What’s the next step?

If you already have a good understanding of your IBS symptoms and have ruled out other potential causes for your gastrointestinal distress, then it’s best to make an appointment with a qualified nutrition professional who can take you through the low FODMAP diet.

If however you’re not yet sure of how severe your IBS is and want to gain a better understanding of what you’re experiencing each day, it’s best to track your symptoms for about a week or so. This will help you to learn which symptoms are most troubling to you, how often they occur, when they occur, and whether there is something specific that might be triggering them. Remember that while IBS is triggered by FODMAPs and other food intolerances in most people, it can also be triggered by stress, illness or other factors.

The best way to do this is by using a symptom diary where you record your IBS symptoms at different times of the day, as well as recording how severely these symptoms are impacting your life. If your symptoms are quite mild and have little impact on your day, you might not need to make adjustments at this time. But if your symptoms are quite severe and are preventing you from living your life the way you want to, then it’s probably time you considered seeking help.

Then once you’re ready, check out this comprehensive guide to starting a low FODMAP diet that I’ve put together to help you.


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