IBS or Intestinal Disaccharidase Deficiency? Find out on your own

A 2023 study found that almost half of the patients presenting with functional gastrointestinal symptoms may suffer from intestinal disaccharidase deficiency! That means that they over-ferment specific sugar molecules; and lactose is just one of them. Find out what causes it and how to test at-home.

Article Highlights
Disaccharidase deficiencies, mimicking IBS symptoms, may go undiagnosed due to their striking resemblance, highlighting the importance of specific disaccharidase activity tests
Disaccharidase enzymes, essential for carbohydrate digestion, when deficient, cause symptoms like abdominal pain, bloating, gas, and diarrhea; thorough diagnosis can prevent misdiagnosis
IBS and disaccharidase deficiency share significant symptom overlap, but distinct diagnosis via duodenal biopsies and breath tests can identify specific disaccharidase activities, leading to accurate treatment
Adopting a low FODMAP diet and sequentially reintroducing lactose and sucrose can indicate specific disaccharidase deficiencies, offering a practical at-home method to discern between IBS and disaccharidase deficiency
Disaccharidase deficiency is more common that once believed
Table of Contents

Disaccharidase deficiency or irritable bowel syndrome?


Every IBS is unique

Lactase deficiency, commonly known as lactose intolerance, where the body struggles to break down lactose, a sugar found predominantly in dairy products, might be familiar to you. However, a less-known but equally significant condition known as disaccharidase deficiency has been emerging in the medical field. Recent research points towards a higher prevalence of this condition in adults than previously assumed. Furthermore, this deficiency may often be obscured by Irritable Bowel Syndrome (IBS) symptoms, increasing the complexity of diagnosis and treatment. 

Disaccharidase deficiency and gastrointestinal symptoms

There are 4 disaccharidases:

  1. Lactase
  2. Sucrase
  3. Maltase
  4. Isomaltase


Every IBS is unique

Disaccharidases play an indispensable role in carbohydrate digestion and absorption. These enzymes, produced within the intestinal brush border, simplify complex sugars into absorbable, simple sugars. Nevertheless, this process is disrupted in individuals with a disaccharidase deficiency.

The deficiency of these enzymes might seem a trivial setback in the vast landscape of digestive functions, but it is indeed a significant one. The deficiency has a direct effect on a person’s health, leading to gastrointestinal symptoms like chronic abdominal pain, gas, bloating, and diarrhea. Alarmingly, individuals deficient in all four disaccharidases, known as ‘pan-disaccharidase deficiency’, experience a more severe weight loss compared to those with a single disaccharidase deficiency.

The symptoms of disaccharidase deficiency show remarkable similarity to IBS, a prevalent gastrointestinal disorder affecting numerous individuals globally. It’s worth noting that some IBS sufferers might, in reality, be struggling with an undiagnosed disaccharidase deficiency.

Different forms of disaccharidase deficiency 

Eating behaviors and the gut microbiome

The average American consumes around 300 grams of carbohydrates and 140 grams of sugar daily. Within these, lactose and sucrose are the most prevalent. In the case of lactase non-persistence, a common phenotype in adults, your body decreases the production of lactase. This lactase deficiency can lead to diarrhea if lactose intake exceeds the gut’s absorption capacity.

The enzyme sucrase has a crucial function in decomposing sucrose into glucose. This enzyme, together with isomaltase, stems from the Sucrase-Isomaltase (SI) gene. A functional variant in this gene can cause sucrose and starch intolerance, known as congenital sucrase-isomaltase deficiency (CSID), an autosomal recessive disorder. Fascinatingly, these variants in the sucrase-isomaltase gene are detected more frequently in IBS patients, creating an interesting connection between disaccharidase deficiency, carbohydrate malabsorption, and IBS.

Causes of secondary disaccharidase deficiency

Primary or secondary

7 tips for faster PI-IBS
recovery time

Disaccharidase deficiencies can be caused by primary or secondary factors, with the onset ranging from birth to adulthood. Primary causes, although rare, are associated with genetic mutations in various genes. In contrast, secondary deficiencies usually arise from damage to the small intestinal mucosa, most commonly from NSAIDs, severe infections, and multiple antibiotics. Managing both types involves dietary strategies. However, while primary deficiencies necessitate treatment throughout one’s life, treatment for secondary disaccharidase deficiencies may only be needed until the recovery of the intestinal lining.
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Diagnosing disaccharidase deficiency in patients

Post Infectious IBS

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Considering the significant symptom overlap between disaccharidase deficiency and IBS, how can one accurately diagnose these conditions? 

The solution resides in a combination of small intestinal biopsies and breath tests. Duodenal biopsies, minute tissue samples from the duodenum — the first part of the small intestine — are recognized as the standard for identifying disaccharidase deficiency. Nonetheless, breath tests offer an invaluable, non-invasive diagnostic tool. Patients with disaccharidase deficiency exhibit certain changes in their breath after sugar consumption, further validating the diagnostic process. Disaccharidase testing using methods like the Dahlqvist method and disaccharidase assay further aids the diagnosis, thereby leading to better diagnosis and treatment outcomes.

This highlights the significance of disaccharidase deficiencies in children and adults alike and the need for early diagnosis to prevent the risk of irritable bowel syndrome and chronic abdominal pain. The crucial role of genetic testing is also underscored to detect the increased risk of irritable bowel syndrome in patients with functional variants in the sucrase-isomaltase gene.

Check disaccharidase deficiency at home

Perform this test and find out

The intricacies of diagnosing disaccharidase deficiency call for a systematic, empirical approach. Owing to the symptomatic overlap between this condition and other gastrointestinal disorders like IBS and celiac disease, it becomes paramount to employ a method that can differentiate between these conditions while diagnosing accurately. The prevalence of disaccharidase deficiencies demands a technique that is both comprehensive and precise. The following steps offer an empirical approach to diagnosing disaccharidase deficiencies, focusing on the individual’s reaction to dietary modifications. These steps align with the objective of detecting disaccharidase levels and identifying specific enzyme deficiencies.

At-home test for disaccharidase deficiency

The steps are:

  1. Eliminate FODMAPs: Start by adopting a low FODMAP diet. This dietary approach is frequently utilized to ease symptoms associated with Irritable Bowel Syndrome (IBS) and might be effective in mitigating symptoms related to disaccharidase deficiencies, including pan-disaccharidase deficiency.

  2. Reintroduce Lactose: 14 days later, reintroduce lactose into your diet. Not too much, just 1/2 glass of milk for 7 days will suffice. If symptoms resurface or exacerbate, it could signal a lactase deficiency, a form of disaccharidase deficiency.

  3. Reintroduce Sucrose: Subsequently (after 7 days), reintroduce sucrose into your diet. If symptoms reappear or worsen upon this reintroduction, this could be indicative of a sucrase deficiency, pointing towards a possible sucrase-isomaltase deficiency.

  4. Perform a Breath Test: If the reintroduction of lactose and sucrose triggers symptoms, it would be prudent to discuss undergoing the 13C-Sucrose Breath Test with your healthcare provider. This non-invasive test can provide crucial insights into potential disaccharidase deficiency, thus proving instrumental in the diagnostic process.

  5. Consult with a Healthcare Provider: If the breath test indicates disaccharidase deficiency, consult with your healthcare provider for appropriate next steps. These could entail enzyme replacement therapy or further dietary modifications to manage symptoms. In some cases, an endoscopy may be recommended to better understand the condition and devise an effective treatment strategy.


How is disaccharide deficiency treated?

Treatment for disaccharidase deficiency hinges on an individual’s specific enzyme deficiency, employing a mix of enzymes and dietary modifications. Levels of deficiency dictate dietary restrictions. Post-antibiotic treatment often necessitates further adaptations due to reduced enzyme levels.

Theodoros Prevedoros
With extensive experience evaluating over 3000 cases in various specialties, including gastroenterology, pediatrics, and endocrinology, Theodoros has collaborated with more than 25 doctors from Greece and Cyprus and over 10 laboratories worldwide.

With a background in Chemistry and Biochemistry from the National and Kapodistrian University of Athens, Theodoros brings a wealth of knowledge in functional medicine and advanced treatments to his role. He possesses exceptional skills in analysis, pattern recognition, diagnostic translation, and storytelling. He is also FMU certified in Functional Medicine and has received training in advanced treatments from the Saisei Mirai Clinic in Japan.
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