What is a Sucrose Intolerance & How Do You Know If You Have It

What is a Sucrose Intolerance, and How Do You Know if You Have It?

If you’re among the ~25-30% of people with irritable bowel syndrome (IBS) who doesn’t get much symptom relief from following a low FODAMP diet (1), and you’ve ruled out other underlying conditions (with help from your treatment team), you could possibly be suffering from a sucrose intolerance – aka an inability to break down, digest, and absorb sucrose from foods.s

Read on to learn more about what sucrose is, the signs and symptoms of a sucrose intolerance, how to tell if you have it, what you can do about it, and more.

What is sucrose?

On the molecular level, sucrose is a type of simple sugar which is made up of equal parts glucose + fructose.  (In other words, “sucrose” is just a fancy chemical name for “sugar”!)

Sucrose vs sugar

From a food science lens, sucrose and sugar are one and the same.  

They both take on many different forms, and can be called different names, which is why it can get confusing. But if you see “sugar” listed on a nutrition label, you can bet that it’s sucrose – and vice versa!

For example, the term “sucrose” is interchangeable with (including, but not limited to) any of the following types of sugar which you may know and love:

  • Beet sugar
  • Cane sugar
  • Domino sugar
  • Brown sugar
  • Granulated sugar
  • Turbinado sugar
  • Sugar in the Raw®

Hidden sucrose in the diet

Unfortunately, finding sucrose on a nutrition label isn’t always that cookie-cutter or black-and-white.  

Most other types of sweeteners (such as maple syrup, molasses, and coconut sugar) still contain some sucrose – but unlike the above sweeteners, they’re not 100% sucrose since they may also contain fructose, glucose, fibers, micronutrients, and other constituents.

  • For example, real maple syrup is only made up of about 60-66% sucrose (2) and coconut palm sugar is about 70-80% sucrose. (3)

High FODMAP sweeteners (such as honey and agave nectar) are made up of mostly fructose, so these would be considered “low sucrose” or even “sucrose-free” foods/sweeteners.

Sucrose in the diet also isn’t limited to the form of sugars and sweeteners – it’s also naturally occurring in certain fruits, veggies, legumes, starches, and more.

But before we dive into that, let’s unpack what it means to have a “sucrose intolerance” since it’s such a common but little-known underlying culprit of IBS. 

Sucrose intolerance: what is it?

A sucrose intolerance is very similar to a lactose intolerance, except instead of being unable to break down lactose (milk sugar), your gut is not able to break down sugar in the form of sucrose, or starch (which gets broken down into sucrose during digestion). (4)

While a lactose intolerance is caused by a missing lactase enzyme (which breaks down lactose in the gut), people with a sucrose intolerance are lacking enough sucrase enzyme (a type of digestive enzyme which breaks down sucrose into glucose + fructose in the gut).

  • In my world of functional nutrition, you may also hear a sucrose intolerance often referred to as a “sucrase isomaltase deficiency.”

Unfortunately, in most of these cases, chronic digestive symptoms have likely been lifelong. 

These people may have also been among the many with IBS who have received colonoscopies and were told everything was “fine.”

For the above reasons, it’s probably no surprise that an estimated ~25-35% of adults with IBS-D / IBS-M and/or hydrogen-dominant small intestinal bacterial overgrowth / “SIBO” actually have an underlying sucrase isomaltase deficiency. (4)

Types of sucrase isomaltase deficiency

There are two types of cases in which you can develop a sucrose intolerance:

  1. Genetic/congenital (primary) sucrase isomaltase deficiency
  2. Acquired (secondary to SIBO) sucrase isomaltase deficiency

While both of these entail lacking the digestive enzyme “sucrase isomaltase” which leads to the inability to properly break down sucrose in the gut, there are two different reasons it can happen.

What causes sucrose intolerance?

Genetic/congenial (primary)

People with a genetic or “primary” case of sucrase isomaltase deficiency were born with one or more gene mutations which block their body’s ability to naturally produce this enzyme in their intestines. (4, 5)  

The result is an inability to break down sucrose from sugars and starches in the intestines, leading to a cascade of symptoms that masquerade as IBS.

People with a genetically-inherited (“primary”) sucrose intolerance are more likely to test negative for SIBO via a breath test, anecdotally based on clinical case study experiences, despite presenting with all the classic symptoms.  These people are also more likely to have struggled with this lifelong.

While congenital sucrase isomaltase deficiency isn’t yet curable (since we can’t change our genetics), the good news is it’s treatable and manageable!

But first, let’s review the second type of sucrase isomaltase deficiency, which is the result of a mismanaged or neglected case of SIBO.

Acquired (secondary to SIBO)

In cases of “acquired” or “secondary” sucrose intolerance, you likely haven’t had these issues for your entire life – your symptoms most likely developed in your body over time, following a case of small intestinal bacterial overgrowth (SIBO) left unchecked for too long.  

  • SIBO is another type of gut disorder which often masquerades as IBS, and which also flies under the radar way too often!

In this case, the intestinal inflammation caused by the overgrowth of unhealthy, pathogenic microbes in your intestines  interferes with the natural enzyme production in the brush border of your intestines, ultimately leading to poorly digested sugars/starches followed by a cascade of unwanted symptoms if you eat anything containing sucrose.

Signs and symptoms of a sucrose intolerance

Much like a lactose intolerance or fructose intolerance, the signs and symptoms of a sucrose intolerance (boh primary or secondary types) can manifest as any of the following IBS/SIBO-like symptoms, usually within a few hours after eating:

  • Gas
  • Bloating
  • Abdominal cramping
  • Diarrhea 
  • IBS-D or IBS-M

Many people with a sucrose intolerance will also notice they feel worse on a low FODMAP diet, (since it increases sucrose intake).

Those presenting with IBS-C (the constipation subtype without diarrhea) are less likely to have sucrose intolerance compared to those with IBS-D or IBS-M. (6)

How to tell if you have it

In my world of clinical and functional nutrition, there are always two ways to tell if you have something: testing or guessing

Neither of those options is inherently better or worse, but there are definitely pros and cons to consider on both sides.

Opinion 1:  Guessing 

If you’re feeling savvy and you’d like to boot-strap your way to Gut Clarity, embarking on a low-sucrose elimination diet (alongside keeping a meticulous food-symptom journal via an IBS food diary) is an exponentially more cost-effective way to determine whether or not you can tolerate, digest and absorb sucrose from food.  

The downside of this approach is it can create a lot of burdensome dietary restrictions, and it can also be a slow process (especially if you’ve got other issues such as food sensitivities, which are common among people IBS-D & IBS-M).

  • This option is probably not the best way to go if you’re already prone to disordered eating, nutritional deficiencies, a very clinically complex case, and/or unintentional weight loss.

Option 2:  Testing

Elimination diets aren’t always appropriate, and some people would rather just spare themselves a bunch of time throwing things at the wall to see what sticks.

While the gold standard for ruling out sucrase-isomaltase deficiency is to do a “sucrase enzyme assay of duodenal biopsies” via an endoscopy, that method is also very invasive, and more expensive than the alternative testing method which is to rule out sucrose malabsorption via breath testing. (4)

Running a sucrose intolerance home breath test to measure your degree of potential sucrose malabsorption may be more expensive than just food journaling alongside an elimination diet, but it’s also more affordable and less invasive compared to the biopsy. This route is also easier from the lens of saving time and unnecessary stress.

How to address it

Okay, so you’ve uncovered that you do in fact have a sucrose intolerance… Now what?!

The good news is it’s manageable and figureoutable; the bad news is the entire process of addressing your sucrose intolerance likely won’t be a cake-walk…

Sucrose intolerance treatment plan (step-by-step)

While this is something I address more in-depth with my 1:1 and group clients via my online program, the Complete Gut Repair Roadmap (over the course of ~3 to 6 months), here’s a 1,000-foot overview of what you can do to start addressing your sucrose intolerance holistically from start to finish:

  1. Keep a detailed food-symptom journal via an IBS food diary.
  2. Begin eliminating foods high in sucrose, and review your food logs with a registered dietitian to determine your sucrose tolerance level (or “threshold”) to various foods containing sucrose.
  3. Rule out and any related underlying root-cause issues (i.e. SIBO, dysbiosis, candida overgrowth, food sensitivities, etc.) which could be impacting the state of your intestinal brush border enzyme production.
  4. If your SIBO test is negative, and you suspect your sucrose intolerance is genetic: consult your doctor and dietitian about the digestive enzyme Sucraid® (sacrosidase) Oral Solution to help your body digest sucrose more efficiently, alongside learning more about a low-sucrose diet.
  5. If your sucrose intolerance was secondary to SIBO:   work your way through the 5R protocol for gut repair (alongside a functional dietitian nutritionist) and then begin reintroducing foods that contain sucrose, one by one, gradually as tolerated.

As a reference, below is a list of high-sucrose foods which you can refer back to as-needed, if you decide to move through a sucrose intolerance diet.

Foods high in sucrose

A food is considered high in sucrose based on the number of grams of sucrose it contains per serving.

If you have a sucrose intolerance, referring to and avoiding/reducing/limiting the following list of high-sucrose foods will likely help you to improve your IBS symptoms (7):


  • Apples
  • Apricots
  • Bananas
  • Cantaloupe
  • Citrus:  oranges, grapefruit, clementines, tangerines, mandarin oranges, tangelos, etc.
  • Dates
  • Guava
  • Honeydew melon
  • Mango
  • Passion fruit
  • Pineapple
  • Passion fruit


  • Beets
  • Butternut squash
  • Carrots
  • Green peas
  • Onions
  • Parsnips
  • Pumpkin

Legumes / proteins

People with a sucrose intolerance can generally eat any type of meat, poultry, or fish/seafood as long as it isn’t made with a high-sucrose type of sauce/seasoning (i.e. garlic, or barbeque sauce which contains a source of added sugar).

Only the following plant-based protein sources naturally contain significant amounts of sucrose: 

  • Black beans
  • Black-eyed peas
  • Chickpeas (“garbanzo beans”)
  • Edamame
  • Kidney beans
  • Lentils
  • Lima beans
  • Navy beans
  • Pinto beans
  • Soybeans
  • Split peas
  • Tofu


  • Cassava
  • Corn / corn flour products
  • Grains (rice, wheat, oatmeal, rye, barley, etc.)
    • Breads, bagels, pastries, crackers, croutons, breadcrumbs, flour, etc.
  • Popcorn
  • Potatoes
  • Sweet potatoes
  • Tapioca starch
  • Yams


  • Garlic
  • Nuts


  • Real maple syrup
  • Coconut palm sugar / “coconut sugar”
  • Beet sugar
  • Cane sugar
  • Brown sugar
  • Domino sugar
  • Granulated sugar
  • Turbinado sugar
  • Sugar in the Raw®

Processed foods

  • Any food containing starch (flour), and/or “sugar” or “sucrose” or “maple syrup” or “coconut sugar” as an added ingredient
    • Desserts
    • Candy
    • Pastries
    • Pancakes/waffles
    • Sauces (i.e. barbecue sauce, tomato sauces with added sugar)
    • Dressings

Additional resources

If you’d like to learn more about how to navigate our complex modern-day food & healthcare system from a holistic lens (according to someone who has been there and done that first-hand), feel free to check out the following resources depending on what’s most relevant for you:


A sucrose intolerance (or inability to break down sucrose and starches in the gut) is a common underlying root-cause of IBS symptoms, silently impacting millions of people worldwide. 

It is caused by a sucrase isomaltase deficiency, which could be lifelong due to certain genetic mutations, or it can also be acquired secondary to an underlying case of SIBO, left unchecked for too long,

Either way, most people with this condition have flown under the radar for many years/decades because sucrose and starch are in so many foods, and because so few practitioners (even in the holistic health space) are familiar with sucrase isomaltase deficiency.

A sucrose intolerance can be identified via a combination of food logging, a low-sucrose elimination diet, a sucrose malabsorption breath test, and/or a sucrase enzyme assay of duodenal biopsies” via an endoscopy, alongside working with your doctor and a functional dietitian who specializes in this.

The best way to address a sucrose intolerance is not just to avoid sucrose-containing foods, but to address and resolve any potential underlying root causes (such as SIBO/dysbiosis) and to lean on sucrase enzymes and/or other types of supplements, as needed.

Since this information is not well-known, and it could make a huge difference for someone suffering from IBS, please share this article! (Knowledge is power, when we have the right mindset and tools to take aligned action based on what we learn.)

XO – Jenna