A concern that many FODMAP diet followers have is FODMAP “stacking.” Stacking refers to the cumulative build-up of FODMAPs in the digestive system over a given period of time. Even if you tolerate a particular low FODMAP food in isolation, consuming multiple servings throughout the day or combining low FODMAP foods can trigger symptoms. This can make the already complex low FODMAP diet even more challenging, especially for those who are particularly sensitive to FODMAPs.

Since each person digests food differently, the way FODMAP stacking may become an issue will vary between individuals. Understanding FODMAP stacking properly can help you avoid digestive symptoms like bloating, gas, and stomach pain while following a personalized low FODMAP diet.

Stacking FODMAPs as defined by Monash University

Monash University, which developed the FODMAP diet, defines stacking as when FODMAPs “add up” in your system before causing symptoms. This can happen when consuming too many servings of low FODMAP foods in the same meal, or by eating too many foods from the same or different FODMAP groups throughout the day.

With FODMAP stacking, multiple portions of low or medium FODMAP-containing foods may cause a build-up of FODMAPs in the gut, leading to digestive issues. For example, you might eat a low FODMAP serving of avocado with breakfast but also chew a piece of sugar-free gum later that morning, leading to FODMAP stacking that exceeds your tolerance for polyols.

How Does FODMAP Stacking Happen?

FODMAP stacking is of particular concern when consuming foods from the same FODMAP category multiple times a day or in large quantities, though it can also occur when two or more foods from different FODMAP groups are eaten.

Food can take as long as three days to move through the entire gut. This delayed digestion means that stacking can happen even if meals are spaced out over time. The "build-up" or stacking of FODMAPs in the digestive system can sometimes be the culprit for lingering or hard to resolve gut issues.

This phenomenon can even happen in extra sensitive folks with irritable bowel syndrome (IBS) if low FODMAP foods are eaten in excess. For example, someone might tolerate a small portion of onion in a sauce but experience discomfort if they consume additional high-fructan foods like garlic, wheat, or asparagus throughout the day.

Stacking could also occur if someone tolerates one serving of a high-FODMAP food, but not two servings. So, the stacking issues in this example would occur if someone ate a tolerable high-FODMAP serving in the morning and then another serving later that day. In this case, you might be able to handle wheat toast in the morning but find that eating another wheat-containing food later in the day exacerbates symptoms.

In short, FODMAP stacking is a concern when:

  • Combining foods from the same FODMAP group throughout the day
  • Consuming multiple foods with different FODMAPs at the same meal
  • Eating large amounts of "green light" low FODMAP foods in a short timeframe

Additional Considerations around FODMAP Stacking

There are also some considerations when it comes to food groups. For example:

  • Fruits and higher-carbohydrate ingredients are more likely to cause stacking because they contain fermentable sugars that can accumulate in the gut quickly.
  • Vegetables, which are lower in carbohydrates, often allow for larger portion sizes before stacking becomes a concern.
  • Protein sources, such as meat, fish, and eggs, are naturally low in FODMAPs and do not contribute to stacking as long as they are simply prepared (watch out for high FODMAP marinades and sauces).

Monash recommends careful timing and serving sizes to avoid stacking concerns and provides examples of FODMAP stacking scenarios.

Common Signs of FODMAP Stacking and Digestive Sensitivity

Symptoms of FODMAP stacking are similar to IBS symptoms, or general FODMAP intolerance. They typically occur between 2-4 hours after a meal, though everyone’s digestive system is different. The timing of symptoms will depend on whether multiple FODMAP groups were consumed in one meal or spread out over several hours.

Common symptoms of FODMAP stacking are:

  • Bloating
  • Gas
  • Abdominal pain
  • Diarrhea
  • Constipation

It’s important to note that food groups are digested differently, meaning that symptoms of FODMAP stacking can vary depending on which FODMAPs are being stacked. In other words, not all FODMAP categories stack the same way.

Some FODMAP groups (like lactose) are more osmotic, while others (like fructan or galacto-oligosaccharides (GOS)) are more likely to be fermented. These different ways that FODMAPs influence digestion contribute to a varying types of symptoms.

If you’re following a low FODMAP diet and not experiencing digestive symptoms, you probably don’t need to worry about FODMAP stacking. However, if you notice that reintroducing foods into your diet leads to bloating, discomfort, or other IBS-like symptoms, FODMAP stacking may be a factor.

How to Avoid FODMAP Stacking: Best Practices

To avoid FODMAP stacking, you first want to have a clear handle on the FODMAP groups and portions you tolerate and those that might trigger IBS symptoms for you. This is best done by working with a FODMAP trained dietitian, who can help you determine:

  • Your individual tolerance levels
  • How different FODMAP types affect your digestion
  • Which portion sizes you tolerate

With a dietitian, you'll develop a personalized plan that is balanced and diverse, but also limits the FODMAPs in your diet based on your tolerance.

For most people, reducing the risk of FODMAP stacking is easiest when eating a wide variety of foods from different FODMAP groups. A varied diet full of minimally processed fruits, vegetables, whole grains, lean protein and low FODMAP dairy is the simplest way to ensure you're not eating too much of any one type of FODMAP. Plus, it's good for your health, too.

Still, if you are experiencing symptoms while eating portions of foods you tolerated during your FODMAP challenges, there is the chance that you could be unknowingly stacking FODMAPs. This is when it may be time to start playing closer attention to the overall FODMAP load of your meals and throughout the day.

The Role of Portion Sizes in FODMAP Stacking

Portion size is highly important when it comes to FODMAP stacking. Even when consuming low FODMAP foods, eating too many servings in a short timeframe can trigger symptoms.

Apps like the Monash Low FODMAP app and FODMAP Friendly app can be helpful to keep track of the amount of FODMAPs you're consuming. The Monash Low FODMAP app uses a red, yellow and green traffic light system to indicate high and low FODMAP portions of foods.

However, sticking to green serving sizes alone isn’t always enough. You'll also need to make sure you're not consuming too many green serving sizes of the same FODMAP category in the same meal. Or even too many green servings of different FODMAP groups.

For example, a fruit salad or smoothie recipe might include several servings of green light portions of various different foods. But too many green light low FODMAP foods can add up to a high FODMAP dish. This high FODMAP dish, composed of multiple servings of green light foods, can trigger symptoms.

When combining foods in a mixed-ingredient dish, consider which FODMAP groups are present and how the FODMAP portions are adding up overall. Over time, you'll learn how you tolerate stacking multiple FODMAPs. Some people will find they can tolerate multiple green light portions as long as they are composed of a variety of FODMAP types, while others may find they cannot eat multiple servings of any green foods.

Timing of Meals and Its Impact on FODMAP Accumulation

FODMAPs have an accumulative effect in the digestive tract so meal timing also matters. Low or moderate FODMAP meals and snacks that are timed too close together can lead to FODMAP stacking.

Even if you carefully plan a breakfast, lunch and dinner to remain low FODMAP, you'll still want to consider the overall FODMAP load of your meals and snacks combined.

For example, if you're careful to use just a 1/4 tsp of garlicky-pesto on your morning eggs but then also use 1/4 tsp of pesto on roasted carrots for lunch 2-3 hours later, this could trigger gut symptoms. Even though each dish individually contains a low FODMAP serving size of pesto, both may be present in the digestive tract at the same time. Instead, you could try using a garlic-infused olive oil instead of the pesto at breakfast or lunch to reduce the total amount of FODMAPs in your meals that day.

How FODZYME can help put FODMAP stacking concerns to rest

If you're already feeling overwhelmed about how to avoid FODMAP stacking you're not alone. There are tools to achieve good symptom control without needing to pay such close attention to the FODMAP content of every individual FODMAP food you consume.

Digestive enzyme solutions like FODZYME® can help by breaking down problematic FODMAPs before they accumulate in your gut.

FODZYME® is a clinically validated digestive enzyme powder designed to break down common FODMAPs like fructan, galacto-oligosaccharides (GOS), and lactose. Instead of timing out your meals to avoid stacking, simply use FODZYME® to break down the FODMAP contents in the foods. By addressing FODMAPs at the point of digestion, this strategy can prevent stacking-related symptoms before they start.

FODZYME® is a simple solution so you don't have to worry about stacking throughout your day. 

Real-World Example: Preventing Fructan Stacking with FODZYME

Say someone is sensitive to fructan (part of the “O” group in FODMAP) and loved pomegranates.

Now, they wish to have a small serving of pomegranate seeds three times today since pomegranates are in season. Fifty-five grams (1/3 a cup) of pomegranate seeds have a “medium” FODMAP rating due to fructan content [3]. Three servings of food with medium FODMAP content could certainly cause stacking-related issues. 

To avoid this, use FODZYME® with some or all of these servings of pomegranate seeds.

How fructan is broken down by FODZYME

FODZYME® allows you to enjoy the foods you're craving, without worry or complex FODMAP math.

  • Having a fruit smoothie? Add FODZYME®, it works great in smoothies and mixing will help integrate the enzymes directly with the FODMAPs.
  • Having yogurt topped with pomegranate? Add some FODZYME®, as it will address the lactose in yogurt and the fructan content in pomegranate.
  • Having some pomegranate seeds on their own? Chew FODZYME® with your first bite or just cover the seeds in our texture-free powder.

Just like that, stacking concerns can be part of your past since the fructan in these pomegranate dishes has been broken down with the help of FODZYME®. Three servings in a day is not a problem anymore!

Now your only concern should be: what to do with all these pomegranates?

FODMAP Stacking Success Stories

A customer recently reached out to us on Instagram with gratitude that FODZYME® is helping her eat more of her favorite vegan protein powder. The protein powder is high in FODMAPs if the serving is large enough, but now with FODZYME®, she's able to "stack" twice as many scoops into her diet!

We love success stories like this. Please let us know: how has FODZYME helped you eat a healthier diet? 

Get started with FODZYME today.