What Are FODMAPS, and What is a Low-FODMAP Diet?

FODMAPs are a group of short-chained carbohydrates, such as sugars and fibers, that the body can’t fully digest or absorb.

Irritable Bowel Syndrome (IBS) is a condition in which individuals experience frequent gastrointestinal symptoms, including bloating, abdominal pain, irregular bowel habits, and gas.

While the exact cause of IBS is unknown, research has suggested that these short-chained carbohydrates may cause or worsen symptoms.

The Low-FODMAP diet was created in 2004 by a research team at Monash University in Melbourne, Australia. It was designed to help reduce symptoms in people who have been medically diagnosed with IBS.

And over the past few years, the diet has gained in popularity in individuals with and without IBS.

So, what is this diet? And what should we know about it? Let’s discuss it!

What are FODMAPs?

FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols.

Here’s a breakdown of what these terms mean:

Fermentable

Some carbohydrates have been found to be more fermentable than others.

So what does that mean?

Well, when these carbs are eaten, bacteria in our gut start to break them down. And this results in the production of gas, which can cause symptoms like bloating and stomach discomfort.

One thing that all high FODMAP foods have in common is that they’re high in these fermentable carbohydrates.

Oligosaccharides

Oligosaccharides are a group of carbohydrates that can be further broken down into two main categories: Fructans and Galactans. 

Examples of high fructan foods: Artichokes, onions, garlic, dried fruits, wheat products, barley, rye, and inulin.

Examples of high galactan foods: Broccoli, Brussels sprouts, lentils, legumes, and soy-based products.  

Disaccharides

Lactose is the most commonly known disaccharide. It’s primarily found in dairy products like milk, soft cheeses, cottage cheese, and yogurt. 

Monosaccharides

Fructose is a monosaccharide that is found mainly in fruits.

Foods high in fructose include apples, honey, agave, high fructose corn syrup, mangoes, and watermelon.

Polyols

Polyols are also known as sugar alcohols.

Sugar alcohols are found in some fruits, vegetables, sweeteners, and sugar-free products. 

Examples of foods high in polyols include cherries, apples, pears, mushrooms, cauliflower, sorbitol, maltitol, and xylitol.

Why do FODMAPs Trigger Symptoms in Individuals with IBS? 

Because FODMAPs are not fully digested and absorbed, they can attract water to the small intestine and may cause bloating and increases in constipation and/or diarrhea.

Additionally, when FODMAPs reach the large intestine, they are fermented by gut bacteria, which causes gas and abdominal pain. 

The Low-FODMAP diet is an eating plan that encourages the utilization of foods that contain smaller amounts of FODMAPs. This has been shown to reduce symptoms of IBS.

What is the Difference Between High FODMAP and Low FODMAP Foods?

High FODMAP foods contain a larger amount of FODMAPs than low FODMAP foods. 

Because there are fewer FODMAPS per serving with low FODMAP foods, they cause less bloating and discomfort in the intestines. 

This is where servings sizes are important. Even if someone with IBS eats a low FODMAP food, they may still have symptoms if they eat a large portion.

Efficacy of the Low-FODMAP Diet

Studies show more improvement in quality of life and IBS symptoms in individuals who have an IBS diagnosis while following a Low-FODMAP diet with the help of a Registered Dietitian compared to a traditional IBS diet.

For comparison, a traditional IBS diet generally involves recommendations for eating 3 portion-controlled meals and snacks per day, chewing thoroughly, and distributing fiber intake throughout the day.

Certain foods like fatty or spicy foods, alcohol, coffee, onions, gassy vegetables (like cabbage), beans, and carbonated beverages are also on the “do not eat” list.

While the overall research on the low FODMAP diet is promising, more research is needed to see whether some IBS subgroups (diarrhea, constipation, or mixed-type) may benefit more from following a low FODMAP diet than others.

Low-FODMAP Diet Timeline 

The Low-FODMAP diet consists of three phases and is designed to be temporary. The overall goal of the diet is to help pinpoint foods that may be causing your IBS symptoms.

After following the diet, the hope is to find a way that an individual with IBS can enjoy different foods with minimal restriction — and minimal discomfort or pain. 

As the initial diet involves cutting out several types of foods, it’s important to work with a registered dietitian. An RD will help make sure that you’re still getting adequate amounts of important nutrients.

In addition to working with a dietitian, you’ll also want to keep a food and symptom journal throughout the entire process. This will help you identify which foods (or a combination of foods) may be causing your symptoms.

Lastly, the low-FODMAP diet is entirely individual. Not all high-FODMAP foods will affect every individual the same.

For example, someone may find in the reintroduction process that they can tolerate lactose, but foods containing fructans are an issue. However, another person may be fine with fructans but cannot tolerate lactose.

Or, someone may be able to handle a smaller portion of a combination food but cannot handle a larger portion.

This reinforces the fact that working with an RD is required in order to help find trigger foods and appropriate food quantities.

Phase 1

Phase 1 is the low FODMAP substitution phase (also referred to as the elimination phase).

During this phase, you’ll eliminate high-FODMAP foods and include only foods that are low in FODMAPs.

Under the supervision of a Registered Dietitian, Phase 1 should last from 2-6 weeks.

As mentioned earlier, working with a dietitian is important as they will help educate you on which foods are allowed during Phase 1 and make sure your diet is nutritionally adequate.

The goal of Phase 1 is for your IBS symptoms to resolve. This way, once you start adding foods back in, you can identify which ones may be causing your symptoms.

Phase 2

Phase 2 is the reintroduction phase. During this phase, you’ll gradually start reintroducing high FODMAP foods to see which groups (or even individual foods) trigger symptoms.

A Registered Dietitian will help guide the individual on which higher FODMAP foods to reintroduce first. 

Foods should be reintroduced one at a time to reduce confusion about potential triggering foods. 

Additionally, foods should be reintroduced in small amounts. Gradually reaching normal serving sizes if the food is not causing unwanted symptoms.

Typically, you’ll reintroduce one group at a time (for example, fructans) and then go back to the elimination/low-FODMAP phase for a few days until you’re symptom-free again. Once that happens, you’ll then start reintroducing the next group (such as lactose).

Phase 3

Phase 3 is FODMAP food personalization to create a long-term eating plan.

At this point, you can add back any high FODMAP foods that didn’t cause unwanted symptoms and avoid (or limit) your intake of those that were found to be problematic for you.

You’ll still want to keep a food and symptom diary during this phase to help identify any trends in your new eating pattern that may be causing the continuation of symptoms.

Who Should Follow a Low-FODMAP Diet?

There are claims that the low-FODMAP diet can help improve gut health, reduce leaky gut, and “boost” the immune system. However, there’s currently insufficient evidence to support these claims.

In fact, several high FODMAP foods are actually great sources of prebiotics, which support the growth of beneficial bacteria in our gut. And a healthy gut microbiome has been linked with benefits for immune health.

The FODMAP diet is designed for individuals who have been diagnosed with IBS. As a result, unless recommended by a dietitian, it’s not meant for healthy individuals or those with other GI-related conditions.

Low-FODMAP and IBD

Irritable Bowel Disease (IBD) is an auto-inflammatory condition within the GI tract and includes Crohn’s disease and ulcerative colitis.

Both diseases may have IBS-like symptoms. However, more research needs to be done regarding the effectiveness of the Low-FODMAP diet and intestinal inflammation.

However, as individuals with IBD are more likely than the general population to also be diagnosed with IBS, the low FODMAP diet may be helpful for some individuals.

It’s important to talk with your doctor about whether your symptoms are more inflammatory (IBD-related) or functional (IBS related), and consult with a Registered Dietitian before trying a low-FODMAP diet.

Do Not Self Diagnose! 

If you are experiencing gastrointestinal symptoms, talk with your doctor before putting yourself on a low FODMAP diet.

Other medical conditions, including endometriosis, irritable bowel disease (IBD), certain cancers, and Celiac disease, may have similar symptoms as IBS. However, the medical treatment for each is different.

The Bottom Line 

The low-FODMAP diet has gained popularity over the past few years in individuals with and without IBS.

However, it’s important to understand that this diet is only recommended for people with diagnosed IBS who are under the supervision of a registered dietitian.

If you’re experiencing unpleasant gastrointestinal symptoms, consult with your doctor or registered dietitian.