Symptoms of Sucrose Intolerance

How to Distinguish Sucrose Intolerance from Other Gastrointestinal Disorders

Many individuals with Sucrose Intolerance, clinically known as Congenital Sucrase-Isomaltase Deficiency (CSID), lack sucrase, the enzyme needed for sucrose digestion. An individual with Sucrose Intolerance cannot digest table sugar and, as a result, develops gastrointestinal symptoms after eating food containing sucrose. Many of those affected with CSID also have irregular amounts of isomaltase and maltase-glucoamylase, the enzymes required for starch digestion. These individuals may experience gastrointestinal symptoms from starch consumption as well.

Those with Sucrose Intolerance may experience mild-to-severe gastrointestinal discomfort when consuming food that contains sucrose as it moves through the small intestine undigested and enters the colon. Resident bacteria within the colon (large intestine) feed on the undigested sugar by a process called fermentation. This fermentation results in increased gas production. When undigested substances are not absorbed in the colon, an osmotic pull of water into the colon causes watery diarrhea. Gastrointestinal symptoms may differ among infants, children, and adults affected by this enzyme deficiency.

Infants and Children

Symptoms of Sucrose Intolerance do not appear in infants until they start ingesting sucrose- and starch-containing foods such as fruit juices, solid foods, common baby foods, milk-based formula, and medications sweetened with sucrose. Infants who are breastfed may not show symptoms until a milk-based formula is introduced into their diet, or they begin eating solid foods.

Chronic abdominal pain, watery diarrhea, and/or failure to thrive (poor physical growth) are common symptoms of Sucrose Intolerance. Abdominal swelling (distention), gassiness, chronic colic, irritability, excoriated (abrasions and irritations) buttocks, vomiting, and diaper rash can all be signs of pediatric Sucrose Intolerance. When symptoms in infants advance to the point of dehydration, malnutrition, muscle wasting, and weakness, hospitalization may be required. However, this occurs in only a minority of cases. Symptoms in children may be more severe than in adults because children have shorter gastrointestinal tracts.

Sucrose Intolerance is often misdiagnosed in infants as chronic, nonspecific diarrhea, called toddler’s diarrhea. Older children are often misdiagnosed as having irritable bowel syndrome (IBS) because cramps, abdominal pain, gas, and intermittent diarrhea are symptoms common to both IBS and Sucrose Intolerance. Unfortunately, older children may learn to live with their symptoms and never be properly diagnosed. Other erroneous diagnoses may include milk protein intolerance, food allergies, and chronic, nonspecific diarrhea. It is important to note that Sucrose Intolerance is a genetic disease that infants and children cannot outgrow.


Adults, too, may learn to live with their gastrointestinal symptoms and accept that their issues are normal. Adult symptoms are similar to those experienced by infants and children; but because the adult gastrointestinal tract is longer, their symptoms may not be as severe or as frequent. Adult symptoms may be limited to increased frequency of loose stools, abdominal distention, and flatulence. Episodic watery diarrhea may occur when ingesting foods containing high levels of sucrose. Also, diarrhea may alternate with constipation, which can contribute to an IBS misdiagnosis.

For infants, children, and adults alike, failure to absorb dietary sucrose and starch can impact the absorption of other nutrients, as well as disrupt the normal hormonal regulation of gastrointestinal functions. Improperly absorbed carbohydrates slow down the rate that consumed food moves from the stomach into the small intestine and, at the same time, accelerate the rate consumed food in the small-intestine moves into the large intestine. These changes in gastrointestinal transit time contribute to the malabsorption of starch, fat, and monosaccharides. The severity of symptoms can be affected by contributing factors such as the quantity of sucrose and starch consumed, the level of bacterial activity in the colon, the absorptive capacity of the colon, and the rates of transit out of the stomach and small intestine.

Recurrent symptoms like chronic diarrhea, unexplained abdominal pain, gas and bloating, weight loss, frequent bowel movements, gassiness, abdominal distention, and vomiting should not be ignored. Any persistent gastrointestinal symptoms should be discussed with a gastroenterologist.

Sucrose Intolerance May Be More Common Than You Think