Sucrose Intolerance: an Overlooked Cause of Digestive Disorders

Kathryn Adel July 26, 2026 FODMAP, gastrointestinal health, Health

Do you suffer from bloating, gas, abdominal pain, or diarrhea? Have you tried various dietary approaches — including the FODMAP* diet — without finding the relief you hoped for? If so, a little-known condition could explain your symptoms: sucrose intolerance.

Although this condition has long been recognized in children, recent research indicates that it is likely underdiagnosed in adults with chronic digestive symptoms. Because its symptoms closely resemble those of irritable bowel syndrome (IBS), it often goes undetected. Yet, once identified, targeted management can make all the difference.

What is a disaccharidase deficiency?

Disaccharidases are enzymes produced by the cells lining the small intestine. Located on the intestinal surface — specifically in the brush border — they enable the digestion of certain carbohydrates (sugars) so that they can be absorbed.

The main enzymes are:

• Lactase, which digests lactose (milk sugar);
• Sucrase, which digests sucrose (table sugar);
• Isomaltase, which plays a role in the digestion of sucrose and certain starches;
• Maltase, which helps complete the digestion of starch.

In individuals with normal activity of these enzymes, sugars such as sucrose are fully digested and absorbed in the small intestine. When the activity of one or more of these enzymes is reduced, some carbohydrates are not completely digested. These carbohydrates then pass into the colon, where they are fermented by intestinal bacteria. This fermentation produces gas and draws water into the intestine, which can cause digestive symptoms. Symptoms vary from person to person and may include gas, bloating, abdominal pain or cramps, abdominal distension (a swollen belly), diarrhea, and sometimes constipation.

The mechanism involved is similar to that of FODMAPs, which is why some experts refer to sucrose as the “6th FODMAP”. While it is not a true FODMAP, it can trigger similar symptoms in individuals with sucrase-isomaltase deficiency. As with FODMAPs, symptoms associated with the maldigestion of sucrose or maltose typically appear two to eight hours after consuming the foods in question.

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Author

Kathryn Adel

Kathryn holds a Bachelor Degree in Nutrition as well as a Bachelor and a Master Degree in Kinesiology, all from Laval University. She is a Registered Dietitian and active member of the Ordre professionnel des Diététistes Nutritionnistes du Québec (ODNQ) and of the American Academy of Nutrition and Dietetics. She holds the Monash University's certification for the FODMAP diet and IBS, and has considerable clinical experience in that area. She is also an accomplished athlete, having ran track and cross-country at a national level. Kathryn specializes in sports nutrition, weight loss, diabetes, as well as heart and gastrointestinal health.