Sucrose intolerance

Sucrose intolerance (also referred to as congenital sucrase-isomaltase deficiency (CSID) (7)/ congenital sucrose-isomaltose malabsorption) is in most cases an autosomal recessive genetic metabolic disease where normal granulated/household sugar (sucrose) is either poorly tolerated or not tolerated at all. Sucrose is also known as saccharose, granulated sugar or its finer ground versions e.g. castor or icing sugar.

primary type

The problem here is an enzyme deficiency in the small intestine (primary type). The enzyme that is responsible for breaking down sucrose (granulated sugar) and maltose (malt sugar) is not functioning properly. It is present, but it is inactive. When it matures it loses the ground under its feet, so to speak – in other words it loses contact with the cell’s membrane - and is then excreted into the small intestine.(1) Both sugars thus cannot be absorbed and will at some point reach the large intestine where they will be decomposed, with the aid of bacteria, into carbon-dioxide and water.

The consequence of this will be symptoms such as diarrhoea, stomach ache, vomiting and a general malaise.

Sucrose-isomaltose malabsorption often only appears from the age of 6 months because this is around the time when this type of sugar is first absorbed by infants through their first solid foods.
Intestinal symptoms in children often include abdominal bloating, vomiting or explosive diarrhea. Clinical symptoms can vary from dehydration, growth failure to milder symptoms in adults.

secondary type

There is also a secondary type: in this case sucrose-isomaltose malabsorption is the result of an intestinal inflammation or other damage to the intestinal mucosa (for instance, that caused by antibiotics...). It can also appear as a consequence of coeliac disease.

Synonyms and prevalence

Dissacharide intolerance = congenital sucrose (=saccharose)-isomaltose malabsorption = congenital sucrose intolerance = (congenital) sucrase (saccharase)-isomaltase deficiency (CSID)

In individuals of European descent, the frequency of sucrose intolerance is estimated at 0.05% to 0.2%. With 3-10% it is higher in so called circumpolar populations like the Inuit or people of Greenland. 2-5)


1) "Journal of Clinical Investigation" (Jacob et al., 106:281-287 (2000))
2) Peterson M, Herber R. Intestinal sucrase deficiency. Trans Assoc Am Physicians 1967; 80:275–283.
3) Welsh J, Poley J, Bhatia M, et al. Intestinal disaccharidase activities in relation to age, race, and mucosal damage. Gastroenterology 1978; 75:847–855.
4) Bell R, Draper H, Bergan JG. Sucrose, lactose, and glucose intolerance in northern Alaskan Eskimos. Am J Clin Nutr 1973; 26:1185–1190.
5) Ellestad-Sayad J, Haworth J, Hildes J. Disaccharide malabsorption and dietary patterns in two Canadian Eskimo communities. Am J Clin Nutr 1978; 31:1473–1478.
6) Uhrich, Stefanie; Wu, Zaining; Huang, Jie-Yu; Scott, C. Ronald; Four Mutations in the SI Gene Are Responsible for the Majority of Clinical Symptoms of CSID; Journal of Pediatric Gastroenterology & Nutrition: November 2012 - Volume 55 - Issue - p S34–S35

7) Sander P, Alfalah M, Keiser M, et al. (January 2006). "Novel mutations in the human sucrase-isomaltase (SI) gene that cause congenital carbohydrate malabsorption". Hum. Mutat. 27 (1): 119


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