Disaccharidase deficiency occurs when the small intestine lacks sufficient amounts of specific enzymes called disaccharidases. These enzymes are responsible for breaking down disaccharides, which are complex sugars found in various foods. Without these enzymes, the body cannot properly digest and absorb these sugars. This leads to digestive discomfort and other potential issues, as undigested sugars pass through the digestive tract. This condition can affect individuals of any age.
Causes of Disaccharidase Deficiency
Disaccharidase deficiencies can arise from various origins, categorized broadly into primary, secondary, and developmental forms.
Primary Deficiencies
Primary deficiencies are genetic conditions, meaning an individual is born with the inability to produce adequate amounts of a specific disaccharidase enzyme. A notable example is Congenital Sucrase-Isomaltase Deficiency (CSID), where individuals have a reduced or absent ability to digest sucrose (table sugar) and isomaltose due to a genetic mutation affecting the sucrase-isomaltase enzyme complex.
Secondary Deficiencies
Secondary, or acquired, deficiencies develop later in life due to damage to the small intestine’s lining, where these enzymes are produced. Conditions that inflame or injure the intestinal villi can lead to this type of deficiency. Common causes include celiac disease, an autoimmune disorder triggered by gluten consumption, Crohn’s disease, a chronic inflammatory bowel condition, or severe gastroenteritis. This form of deficiency can sometimes be temporary, with enzyme function potentially improving once the underlying intestinal damage is resolved or managed.
Developmental Deficiencies
A third category, developmental deficiency, is observed primarily in premature infants. Their digestive systems are not yet fully mature at birth, meaning they may not produce sufficient levels of disaccharidases. This immaturity often results in a temporary inability to digest certain sugars, such as lactose. As these infants continue to develop, their enzyme production typically increases, and the deficiency resolves over time.
Symptoms and Associated Complications
When disaccharidase enzymes are deficient, undigested disaccharides pass from the small intestine into the large intestine. In the large intestine, gut bacteria ferment these unabsorbed sugars, producing gases and drawing water into the bowel. This fermentation process causes the digestive symptoms experienced by affected individuals.
Common symptoms include osmotic diarrhea, characterized by loose, watery stools. Abdominal bloating, excessive gas (flatulence), and cramping abdominal pain are also frequently reported as the bacteria produce gas during fermentation. The severity of these symptoms often correlates with the amount of the undigested sugar consumed.
If a disaccharidase deficiency remains unmanaged, particularly in infants and children, it can lead to more serious complications. Persistent diarrhea and malabsorption can result in malnutrition, as the body struggles to absorb necessary nutrients from food. Dehydration is another potential concern due to ongoing fluid loss from frequent bowel movements. In young children, a prolonged state of malabsorption and inadequate nutrient intake can hinder growth and development, leading to a condition known as failure to thrive.
The Diagnostic Process
Identifying a disaccharidase deficiency typically begins with a thorough review of the patient’s symptoms and a detailed dietary history by a healthcare professional. Understanding which foods trigger symptoms provides initial clues, helping guide further diagnostic steps to confirm the presence of an enzyme deficiency.
The hydrogen breath test is a common non-invasive diagnostic tool used to detect disaccharidase deficiencies. For this test, the patient consumes a specific sugar, such as lactose or sucrose. If the enzyme is deficient, the undigested sugar reaches the large intestine, where bacteria ferment it, producing hydrogen gas. This hydrogen gas is then absorbed into the bloodstream and exhaled, measured in breath samples collected at regular intervals.
The gold standard for diagnosing disaccharidase deficiency involves an upper endoscopy with a biopsy of the small intestine. During this procedure, a thin, flexible tube with a camera is inserted through the mouth to visualize the upper digestive tract and take small tissue samples from the small intestine. These biopsy samples are analyzed in a laboratory to directly measure the activity levels of specific disaccharidase enzymes, providing a precise diagnosis. Other tests, such as a stool acidity test, may also be used, particularly for infants. This test measures the pH of stool samples, as the fermentation of undigested sugars by bacteria can produce acidic byproducts, lowering stool pH.
Managing the Condition
Managing disaccharidase deficiency primarily involves dietary modification to reduce or eliminate the intake of the specific sugar that cannot be properly digested. For instance, individuals with lactase deficiency must avoid or limit dairy products containing lactose, while those with sucrase-isomaltase deficiency need to restrict sucrose found in table sugar, many fruits, and processed foods. Working closely with a registered dietitian is highly beneficial, as they can help create a balanced meal plan that avoids problematic sugars while ensuring adequate nutrition.
Enzyme replacement therapy offers another approach to managing the condition. This involves taking enzyme supplements that provide the missing disaccharidase. For example, individuals with lactase deficiency can take over-the-counter lactase pills before consuming dairy products, which helps break down the lactose. For Congenital Sucrase-Isomaltase Deficiency, a prescription enzyme replacement called sacrosidase (Sucraid®) is available, which helps digest sucrose. These supplements replace the body’s deficient enzymes, allowing for better digestion of specific sugars.
For secondary disaccharidase deficiencies, addressing the underlying condition that caused the intestinal damage is a key part of the management strategy. Treating conditions like celiac disease by adhering to a gluten-free diet, or managing inflammatory bowel diseases such as Crohn’s disease with appropriate medical therapies, can allow the small intestine to heal. As the intestinal lining recovers, its ability to produce disaccharidase enzymes may improve, potentially alleviating or resolving the secondary deficiency over time.