The low FODMAP diet is an elimination diet that is often used to manage the symptoms of irritable bowel syndrome (IBS). Many people mistakenly think the low FODMAP diet only has one phase, but it actually consists of three distinct phases. 

Before getting started with low-FODMAP diet, there are several things to know. The three phases of the low FODMAP diet are equally important, with the progression through the phases designed to help you identify your personal trigger foods and FODMAP thresholds. By identifying your body's reaction to different FODMAP groups, you can start to manage your reactions and symptoms more effectively, without having to stick to a very restrictive diet.

If you're feeling lost when it comes to progressing through the FODMAP reintroduction phase, don't worry. This article will help you understand how to do FODMAP reintroduction so you can manage your IBS symptoms with as varied a diet as possible.

Understanding the three phases of a low-FODMAP diet

Before diving into the phases of the low FODMAP diet, you're probably wondering: What are FODMAPS? Briefly, FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. They are short-chain carbohydrates that resist digestion and instead move to the large intestine intact. Here, they're fermented by your gut bacteria, which produces gas and, in some cases, draws water into the intestines. This can trigger your IBS symptoms like gas, bloating, abdominal pain, and changes in bowel movements.

There are five FODMAP groups: Fructans, galacto-oligosaccharides (GOS), lactose (found in dairy products), excess fructose, and polyols (often used as artificial sweeteners). Different foods contain different FODMAPs, with some foods containing more than one of the FODMAP groups. 

Apps like the Monash University FODMAP app can help you determine which type of FODMAP various foods contain. Different FODMAP groups trigger different symptoms, so it's important to know which types of FODMAPs a food contains. For example, polyols, which draw water into the bowel, can cause diarrhea, while GOS frequently cause gas and bloating.

The low FODMAP diet is an elimination diet frequently used to manage IBS symptoms. As we've already mentioned, the low FODMAP diet is made up of three distinct phases: Elimination, reintroduction, and integration (also called maintenance or personalization). Let's review each phase in more detail.

Phase 1. Elimination phase

The first phase of the low FODMAP diet is the elimination phase. During the elimination phase, you'll replace high-FODMAP foods with lower-FODMAP alternatives. The goal of the elimination phase is to get your symptoms under control by limiting your intake of FODMAPs. This phase typically lasts between two and six weeks, depending on how long it takes to get your symptoms under control.

During the elimination phase, using FODMAP-friendly recipes can be helpful for sticking to the diet. Using dietitian-approved recipes can help take the guesswork out of meal planning, and following a low FODMAP shopping list can help make grocery shopping less stressful.

It's worth noting that if your symptoms haven't improved at all after four weeks, you may be a FODMAP non-responder. Research shows that up to 86% of people with IBS find relief by following a low FODMAP diet. However, if you're one of the people who doesn't find relief on the low FODMAP diet, it may be that FODMAPs are not responsible for your symptoms, and you may need to explore other IBS management strategies, such as gut-directed hypnotherapy or cognitive behavioral therapy.

Phase 2. Reintroduction phase

Once you've completed the elimination phase, it's time to start FODMAP reintroduction by doing challenge food tests. This phase is where you collect data so you can understand your individual FODMAP triggers. 

Lasting from eight to twelve weeks, this phase requires you to start reintroducing high FODMAP foods into your diet, one FODMAP group at a time. Think about it as a series of challenges for your gut.

The trick in this phase is to give your body enough time to ‘deal with' the foods being reintroduced. It's generally best to have two to three days between each food reintroduction. During this time, you'll increase your portion size of the food being tested to assess your individual FODMAP thresholds. For most FODMAP groups being reintroduced, you'll try two or three gradually larger portion sizes before moving on to the next FODMAP group.

Navigating the reintroduction phase of the low FODMAP diet can be particularly challenging, but it is important to reintroduce foods to learn your food triggers, tolerances, and build a balanced diet that promotes digestive health and gives you more food freedom.

Phase 3. Integration phase

Lastly, you'll move on to the integration or maintenance phase. Once you've identified your trigger foods and tolerance thresholds by doing FODMAP reintroduction, it's all about finding a balance between including the FODMAP groups you can tolerate while avoiding the ones that trigger your symptoms. This phase is highly individual, as every person will have different thresholds and tolerance levels. 

But let's back up a bit and return to the reintroduction phase. Many people experience significant symptom relief and an improvement in overall well-being during the elimination phase, and may decide to comfortably stay in phase one, avoiding FODMAP reintroduction altogether. In this case, ‘comfortable’ means achieving control of symptoms, but it also means having to avoid major groups of delicious, nutritious foods. These foods are not only hard to deny yourself, but also, at times, impossible to avoid. This especially applies to social occasions, eating out, and anything that doesn't involve you making everything from scratch. 

Staying in the elimination phase doesn't just impact your social life. It also deprives your body of essential nutrients that can be hard to find in low FODMAP alternatives. 

Why the FODMAP Reintroduction Phase Matters

There are many benefits to reintroducing FODMAPs into your diet. Here are a few reasons to start FODMAP reintroduction once your symptoms are under control.

Identify your personal FODMAP thresholds

Remember, the elimination phase of the low FODMAP diet involves eliminating all FODMAP groups (fructans, GOS, lactose, excess fructose, and polyols). This can result in an extremely limited diet. However, this degree of FODMAP restriction usually isn't necessary, as most people are not intolerant to all FODMAP groups.

By reintroducing the FODMAP groups one at a time, you can manage IBS symptoms while still eating some foods that are high in FODMAPs. Plus, the reintroduction phase enables you to determine whether there's a threshold for your symptoms when it comes to your FODMAP food triggers. 

For example, you may learn during the reintroduction phase that you can tolerate one clove of garlic per meal. This is valuable knowledge to have, because it means you may be able to include even your trigger foods in small amounts. This results in a much more varied diet, which can be beneficial for both your physical and mental health (the mental load of restricting a wide range of food can be extremely draining).

Support your gut microbiome

Many high FODMAP foods act as prebiotics (food for your good gut microorganisms). When you eliminate all high FODMAP foods, you're essentially starving your gut microbiome, which may be detrimental to your gut health. While we're still learning about the long-term effects of the low FODMAP diet, some research suggests that even temporary elimination of FODMAPs can reduce the amount of good bacteria (like Bifidobacterium species) in your gut.

Increase dietary variety and nutrients

Following a low FODMAP diet long-term can lead to not getting enough of certain nutrients, like calcium, iron, vitamin D, and fiber. Some people may also lose weight on the low FODMAP diet because they're not eating enough calories to sustain them. When you reintroduce foods you can tolerate, you're more likely to be getting enough of the nutrients your body needs. Plus, eating will be more fun when you have a wider variety of foods to choose from!

Establish a healthier relationship with food 

Gastrointestinal symptoms like gas, bloating, and constipation are extremely common in people with eating disorders. Plus, research shows that disordered eating behaviors may be more common in people with IBS. This makes sense, as restricting as many foods as are restricted on the low FODMAP diet can damage your relationship with food and may negatively impact your gut health. 

By reintroducing foods in amounts your body can tolerate, you open the door to having a healthier, more peaceful relationship with food. This can free up a lot of mental space and make eating feel less stressful overall.

When and how to reintroduce FODMAPs

Once you get your symptoms under control during the elimination phase, you need to remain on the low FODMAP diet during the series of food challenges. That means that even if you determine that you can tolerate a particular test food, you should continue avoiding it until the reintroduction phase is over. This helps prevent FODMAP stacking, where eating FODMAPs from different FODMAP groups can overflow your FODMAP "bucket," leading to digestive symptoms. It also means you can get a clear picture on how you tolerate each FODMAP individually.

It's important to carefully track every test food challenge and its outcomes, including your tolerance levels to each of the high FODMAP foods and the symptoms you experience. This can help you determine both which foods you can tolerate and the portion sizes that work best for you.

How to Safely Reintroduce Foods

  • Remain on the low-FODMAP diet until the end of the reintroduction phase.
  • Each FODMAP group should be tested separately by using the test food list in the next section. This ensures the food you're testing doesn't contain more than one FODMAP group.
  • Ensure that each test consists of at least two to three increasingly larger portion sizes to assess your FODMAP threshold accurately.
  • Be cautious of FODMAP stacking.

FODMAP groups and foods for reintroduction testing

While you may be aware of the different FODMAP groups, it's important to test your tolerance levels with a specific test food that does not contain more than one FODMAP group. Below are the examples of recommended challenge foods with their respective FODMAP groups, that don't contain group overlaps. If you'd prefer to use different foods, use the Monash University FODMAP app to choose test foods that contain only one FODMAP group.

  • Lactose: Cow's milk (start with ¼ cup, then ½ cup, then 1 cup)
  • Excess fructose: Freshly squeezed orange juice (start with ½ cup, then ⅔ cup, then ¾  cup)
  • Sorbitol: Cherries (start with 4 medium, then 5 medium, then 6 medium) 
  • Mannitol: Celery stalks (start with 2 medium stalks, then 2½ medium stalks, then 3 medium stalks) 
  • GOS: Canned and drained pinto beans (start with 4 tablespoons, then 5, then 6 tablespoons). 
  • Fructans (grain foods): Cooked wheat pasta (start with ½ cup, then ⅔ cup, then 1 cup)
  • Fructans (vegetables and fruit): Ripe banana (start with ½ medium, then ¾  medium, then 1 medium)
  • Fructans (garlic): Garlic clove (start with ⅓ clove, then ⅔  clove, then 1 clove). It's important to test garlic separately from other fructan foods, as some people may be sensitive to garlic but not other types of fructans.
  • Fructans (onion): Any variety of onion (start with 1 tablespoon, then 1 ½ tablespoons, then 2 tablespoons) 

There is a reason why fructan is one of the most common troublemakers within FODMAPs. Foods often contain a mixture of different types of fructans, and it can be difficult to measure the exact mix of every type of fructan in a food. So instead, looking at ‘total fructans' is going to work better when quantifying these foods. This is why, when picking testing foods, it's important to test grain foods, vegetables and fruit, garlic, and onions separately.

How to manage symptom flare-ups during reintroduction

If you've found relief by eliminating FODMAPs, reintroducing foods through a FODMAP challenge can be nerve-wracking, especially if symptoms like gas and bloating return. But it's important to remember that some discomfort doesn't always mean a full intolerance. Instead of stopping the entire reintroduction phase altogether, here are a few options to manage flare-ups and make further testing less stressful.

Adjust the portion size

If you have a reaction during the challenge phase, it might not be the food, but rather, the portion size. Try reducing the portion size and then continue testing. Many people can tolerate small amounts of high FODMAP foods, even if larger portions cause symptoms. Taking this approach can help you find your personal threshold, which is more useful and sustainable than having to eat strictly low FODMAP forever.

Space out testing days

If symptoms arise during the reintroduction phase, give your gut time to rest before the next FODMAP challenge. Pause testing and wait for at least two to three symptom-free days before starting a new food challenge. This helps you get a clearer picture of what caused the flare and prevents overlapping reactions.

Stay on top of your sleep and stress management during reintroduction

While food intolerance can trigger symptoms, we also know that poor sleep and stress can cause digestive symptoms in people with IBS. If you experience symptoms during reintroduction, take a look at your sleep schedule and stress levels. If you're not sleeping well or are very stressed during the challenge phase, it's possible that's what's causing your symptoms — not the high FODMAP foods.

If you're struggling to sleep, avoid looking at screens for at least two hours before bed, and make sure your bedroom is cool and dark to promote restful sleep. Stress management techniques like deep breathing, meditation, and yoga can also help. Remember, it's best to undergo the reintroduction phase during a time when stress is minimal to ensure that stress doesn't impact the results of the different food challenges.

Use digestive enzymes

Digestive enzymes can help break down certain FODMAPs more effectively. For example, FODZYME is designed to target three types of FODMAPS: fructans, GOS, and lactose. It breaks them down before they reach your gut and ferment, thereby reducing symptoms like gas, bloating, and abdominal discomfort. 

Using a digestive enzyme after a ‘failed’ reintroduction test can help you learn if you can in fact tolerate that FODMAP, just with the help of a digestive enzyme. They can help reduce the severity of symptoms while still allowing you to include this FODMAP group on your diet long-term. They can be a useful tool for smoother testing and long-term dietary flexibility.

Signs you're ready for reintroduction

The reintroduction phase is a key part of the low FODMAP diet because it's how you learn your personal triggers and expand your food choices. But how do you know when you're ready to start testing foods? Here are some clear signs you're ready:

  1. Your IBS symptoms have improved: If you've been following a strict low FODMAP diet for two to six weeks and your digestive symptoms have significantly improved or become more predictable, you're likely ready to move on.
  2. Your diet is consistent: If you're constantly eating a variety of low FODMAP foods without accidentally eating foods high in FODMAPs, you're likely ready to move on. A stable, low FODMAP baseline diet makes it easier to identify whether your symptoms are caused by reintroduced foods.
  3. You feel confident and prepared: If you have a good understanding of how the reintroduction phase works, including with FODMAP groups to test, how to test them, and how to monitor symptoms (such as a symptom and food journal), you're likely ready to start reintroducing foods.
  4. You're working with a registered dietitian: This is ideal, but not required. A dietitian can guide you through the reintroduction phase and help you interpret test results.

Once these boxes are checked, you're ready to start the reintroduction phase and move one step closer to a more flexible, personalized diet.

Challenges of long-term low FODMAP diets

Once your triggers and thresholds are identified and you're comfortable in knowing how to manage them through a personalized low FODMAP diet, there isn't a lot of advice out there on how to manage this long-term. For some of us, it's more manageable than others, yet restricting these food groups for good can be a challenge.

Here are some of the most common challenges of the low FODMAP diet:

  • Eating out at restaurants: Eating out while managing FODMAPs can be tricky, and date nights with IBS can feel stressful before they've even begun.
  • Traveling: Just like eating out, traveling while following a strict low FODMAP diet can be challenging. While it can be helpful to pack your own travel snacks, most people would likely find traveling easier if they weren't avoiding all FODMAPs.
  • Nutritional deficiencies: Restricting your intake of high FODMAP foods long-term can reduce your intake of fiber, prebiotics, and key nutrients like calcium, iron, and vitamin D.
  • Gut microbiome changes: The low FODMAP diet can reduce beneficial bacteria due to a reduced intake of prebiotics, which act as fuel for your good gut microbes.
  • Social and emotional strain: The low FODMAP diet can feel isolating and stressful, and constant food vigilance may contribute to anxiety or disordered eating patterns.
  • Cost and accessibility: Specialty low FODMAP products can be hard to find at regular grocery stores and are often more expensive. 
  • Over-reliance on packaged foods: Some people turn to processed low FODMAP snacks and products, which may be lower in fiber and nutrients than whole foods. This may lead to an inadvertent decrease in overall diet quality.

As you can see, following a low FODMAP diet long-term can be challenging and may negatively impact your health. That's why the FODMAP reintroduction phase is so important.

How digestive enzymes can support FODMAP reintroduction

While you may be familiar with enzymes, it may not be extremely clear as to how they can help and, more importantly, which enzymes you need to take to make them work for you. 

At the most basic levels, enzymes are proteins that regulate the rate at which different metabolic and chemical processes occur. Often referred to as biological catalysts, enzymes are highly specialized proteins that act on a specific molecule, called the enzyme's substrate. One instance some of us are familiar with is when specific digestive enzymes break down the various components, such as carbohydrates, fats, and proteins, in the food we eat. This process allows our bodies to absorb the nutrients it offers and turn them into energy.

Benefits of using enzymes during reintroduction

  • Prevent the effects of FODMAPs on the digestive system, like digestive discomfort, pain, or other symptoms.
  • Help you receive the nutritional benefits from foods that you might otherwise avoid.
  • Enable dietary diversity and food freedom, and allow you to lift the restrictions placed by the low FODMAP diet.

While rapidly fermentable fibers like FODMAPs promote gut health, they can also cause trouble for people with increased gut sensitivities. Using digestive enzymes can enable you to receive nutritional benefits without having digestive discomfort, pain, or other symptoms.

Digestive enzymes for FODMAPs do not act on the body. Instead, they act on the food your body has trouble digesting.

FODZYME's enzyme blend as a solution for FODMAP sensitivity

FODZYME® is the world's first enzyme blend to tackle the FODMAPs fructan, GOS, and lactose directly. If you are wondering about polyols, we are working on a novel polyol-targeting enzyme as we speak. Our enzymes are very specialized proteins produced by microorganisms that break down specific substrates, in this case, FODMAP molecules.

Here's a brief overview of what FODZYME® is and how it works: 

  • Contains fructan hydrolase (acts on fructan), alpha-galactosidase (acts on GOS), and lactase (acts on lactose).
  • Breaks down FODMAPs as you digest your meal, effectively reducing FODMAPs in your gut.
  • Comes in powder form for maximum integration with high-FODMAP foods.

Clinical Evidence Supporting FODZYME

FODZYME® was administered concurrently with three grams of inulin (a common source of fructan) in SHIME®, a multi-compartment, scientifically validated model of the complete human gut, to study the efficacy of FODZYME's fructan hydrolase in fructan breakdown.

Lactase and alpha-galactosidase, the two other enzymes in FODZYME's formulation, were assessed as an additional control arm to verify the specificity of fructan hydrolase in fructan breakdown. 

Findings indicated a rapid breakdown of fructan to fructose in gastric conditions, with approximately 90% of the inulin mass converted to fructose within 30 minutes, thus demonstrating resilience to both stomach pH and protease activity (in other words, the fructan hydrolase enzyme was not damaged by stomach acid or enzymes that break down proteins). The study also showed that 70% of fructose was absorbed during the simulated small intestinal transit, thus reducing gas. 

You can learn more on the science here.

Remember, FODZYME® breaks down the FODMAPs fructan, lactose, and GOS, helping you enjoy your favorite meals with confidence and giving your body the nutrients it deserves.

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