Explaining FODMAPs and the FODMAP diet

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. 

These are small carbohydrates, or sugars, that your body can’t digest. In some people, they can cause gastrointestinal (GI) symptoms. A FODMAP diet is a diet that is low in FODMAPs.

Scientists at Monash University developed this diet to help people with specific gut issues, so it isn't for everyone.

However, for people with irritable bowel syndrome (IBS) or specific digestive problems, a low FODMAP diet can help improve symptoms.

This article will give you an overview of what FODMAPs are, how they affect your bowels, and what you can eat on a low FODMAP diet. 

FODMAPs explained

Around two-thirds of people with IBS perceive that their GI symptoms are related to food. But food likely plays a part in the symptoms of all people with IBS.

Experts are interested in FODMAPs because they can trigger abdominal symptoms in some people with IBS. 

The most common FODMAPs are carbohydrates such as:

  • Oligosaccharides: foods like garlic, onions, legumes, and wheat.

  • Disaccharides: mainly sucrose, lactose (mostly in dairy products), and maltose.

  • Monosaccharides: simple sugars such as fructose and glucose found in fruit, honey, and sugary drinks.

  • Polyols: found in stone fruits, many sugar-free sweeteners, and some vegetables like mushrooms.

These are just a few examples. We’ll go into more detail about foods that are high and low in FODMAPs below. 

What happens to FODMAPs in the body?

Not everyone is sensitive to FODMAPs, and, for most people, they pass through the digestive system with little change. 

But, if you are sensitive, a FODMAP can have several effects when it reaches your intestines:

  • FODMAPs draw fluid into the bowel, which can contribute to diarrhea. 

  • They quickly begin to ferment, producing gas. The increased gas can distend the bowel leading to pain or discomfort.

  • Gut bacteria that feed on FODMAPs tend to produce hydrogen. Hydrogen is more likely to cause abdominal cramping, pain, discomfort, and constipation.

  • The bowel can respond differently between people, and the bowel contents might move faster or slower. This can lead to either diarrhea or constipation.

As mentioned, not everyone will have this reaction to FODMAPs. To date, most of the research has focused on people with IBS.

However, scientists are exploring the role of FODMAPs in other gut health conditions, including ulcerative colitis and Crohn’s disease.

FODMAPs aren’t something that most people need to avoid. They can act as prebiotics, which help boost your beneficial gut bacteria. 

According to one review, the low FODMAP diet is associated with changes in the gut microbiome, including reduced levels of Bifidobacteria, which are “good” bacteria. 

ZOE is at the forefront of microbiome research. Our research has identified 15 "good" bacteria associated with positive health markers and 15 "bad" bacteria associated with poor health markers.

If you want to know which bacteria are in your gut and how to encourage the "good" bugs, start by taking our free quiz today.

If you are struggling with IBS symptoms, a FODMAP diet could be something you choose to explore. So, let's delve into the diet in a little more detail. 

What is the FODMAP diet?

Experts at Monash University primarily designed the FODMAP diet for people with IBS.

IBS is a very common condition affecting the digestive system. Around 10-20% of people live with IBS, and it is twice as common in women than men. 

Symptoms of IBS can vary greatly from person to person. However, the main symptoms are stomach pain, bloating, constipation, diarrhea, and abdominal distention. IBS can significantly impact an individual’s quality of life.

Thankfully, the FODMAP diet can help. Studies have shown that up to 86% of people with IBS had improved symptoms after following the diet. 

But a diet low in FODMAPs is not easy to follow. It's very restrictive, especially at the start when you cut out all foods high in FODMAPs. After eliminating these foods, the goal is to slowly reintroduce them one at a time. 

This way, you can determine which foods are triggering your symptoms. 

It’s important to note that the FODMAP diet is not meant as a long-term diet plan — the exclusion phase, where you eliminate high FODMAP foods, lasts 2–6 weeks, maximum. 

Then, there is the challenge phase, where you introduce FODMPAPs one at a time. You then re-introduce the FODMAPs you tolerate and introduce those you are sensitive to at lower levels.

Before trying the FODMAP diet, you should improve overall diet quality and identify other potential triggers, such as caffeine, spicy foods, and irregular meal times. 

Then, you can try a low FODMAP diet, but it’s best to speak with a dietician to ensure you meet all your nutritional needs.

It’s also important to note that people who have experienced an eating disorder should not try the low FODMAP diet.

Foods high in FODMAPs

To know where to begin, you must first understand which foods to avoid. These foods are high in FODMAPs:

  • Grains: wheat, rye, and barley-based breads, breakfast cereals, biscuits.

  • Vegetables: onion, garlic, artichokes, asparagus, cauliflower, green peas, mushrooms, and sugar snap peas.

  • Fruit: watermelon, peaches, nectarines, apples, pears, mango, cherries, and dried fruit.

  • Beans and pulses: most pulses and legumes.

  • Dairy products: cow’s milk, yogurt, ice cream, evaporated milk, custard, condensed milk, and soy milk.

  • Sugars and sweeteners: honey, corn syrup, and sugar-free confectionery.

  • Nuts and seeds: cashews and pistachios.

What can you eat on a FODMAP diet?

FODMAPs occur in carbohydrate foods. That means foods without carbs, such as meat, fish, and eggs, are FODMAP-free. 

Also, quantity matters — 1 cup of something might contain high levels of FODMAPs, but a half-cup could be classed as low in FODMAPs.

Here are some other foods that are low in FODMAPs:

  • Grains: sourdough spelt bread, quinoa flakes, corn flakes, oats, plain rice cakes, and sourdough bread and pasta made from quinoa, rice, or corn.

  • Vegetables: eggplant, green beans, bok choy, red bell pepper, carrot, cucumber, lettuce, potato, and zucchini.

  • Fruit: cantaloupe, kiwi fruit, pineapple, mandarin, pineapple, and orange.

  • Dairy and alternatives: almond milk, rice milk, lactose-free milk, soy milk (made from soy protein), brie, camembert, feta cheese, and hard cheeses.

  • Sugars and sweeteners: maple syrup, table sugar, rice malt syrup, and dark chocolate.

  • Nuts and seeds: macadamias, peanuts, pumpkin seeds, sunflower seeds, and walnuts.

How to start the FODMAP diet

Although it is called a low FODMAP "diet," it is not a weight-loss plan. Instead, it is for people with IBS. It’s a specific, short-term prescriptive plan to determine which foods aggravate your symptoms. 

Before starting a FODMAP diet, you should consult a doctor or dietician. 

Since it’s very restrictive and not suitable for everyone, it will help to have clinical support to guide you through the process. If you haven’t received a medical diagnosis of IBS from a doctor, this diet is not for you. 

Step 1

The FODMAP diet begins with a 2–6 week period of high restriction. The first step is to remove all foods high in FODMAPs from your diet and replace them with low FODMAP alternatives. It may take a few weeks to see any improvement. 

Step 2

Once you see an improvement in your symptoms, it's time to take the next step.

Under the guidance of your dietician or doctor, you can methodically reintroduce one type of FODMAP at a time at increasing levels — to see how much produces symptoms. 

The aim is to reintroduce each FODMAP subgroup separately over 3 days. 

You should record your symptoms to see if the food you have added to your diet causes aggravation. Reintroducing foods can take around 6–8 weeks. 

A dietician can help guide you through the process to ensure you reintroduce high FODMAP foods at the right time and know what symptoms to look out for. They will also ensure that you are still consuming all the nutrients you need to stay healthy.

A dietician will help you figure out which FODMAPs you are sensitive to and how much you can tolerate.

Step 3

Finally, once you have established which foods make your IBS worse, you can build your personalized FODMAP diet for long-term symptom management. 

At this stage, you will only limit the FODMAPs that trigger symptoms and can continue eating the ones you tolerate well. You can also try to slowly reintroduce the FODMAPs you are sensitive to.

It's important to remember that FODMAP foods are generally good for you and that the restrictive element of the diet is not continual. Instead, the purpose is to find out what aggravates your digestive issues in the first place.

At ZOE, we understand that everyone responds differently to foods. This is why personalized nutrition is so important. Using our at-home test, you can understand how your blood fat and blood sugar levels respond to foods. 

We also analyze your gut bacteria. From this information, we tell you which foods best suit your body, helping you move toward your long-term health goals.

Find out more by taking our free quiz today.

Summarizing the FODMAP diet

IBS symptoms can be debilitating and adversely affect your life. Research from Monash University shows that 3 out of 4 people who follow a low FODMAP diet will see an improvement in their symptoms. 

Therefore, 1 out of 4 people will not benefit from a FODMAP diet and will need to speak with their doctor about other IBS therapies. It isn't suitable for everyone and isn't a cure for IBS. 

There are a few key points to take away from this article:

  1. The FODMAP diet is not for everyone, and clinicians designed it for people with a medical diagnosis of IBS.

  2. It is not a weight-loss diet.

  3. The FODMAP diet aims to determine your IBS triggers and develop a management strategy.

  4. The FODMAP diet should always be done under the guidance of a dietitian or doctor.

  5. You should try other dietary approaches before the FODMAP diet.

It can be challenging to follow a low FODMAP diet on your own. It is best to seek advice from a doctor or dietitian who can support you through the process.

This will give you the best chance to carry out the diet effectively and see if it helps manage your IBS symptoms. 


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