Sucrose Intolerance

What is Sucrose intolerance?

Sucrose intolerance results from the inability to digest sucrose, or ‘table sugar.’ Beyond its presence in cane sugar, sucrose is the primary sugar in maple syrup, many fruits and even a few vegetables.

An enzyme called “sucrase isomaltase” that is expressed on the surface of the small intestine cells digests sucrose molecules, which are then absorbed into the blood stream. If inadequate enzyme is present, the sucrose is not absorbed and passes into the colon, where intestinal bacteria digest it, producing gas, bloating and discomfort.

Once thought to be a rare condition that is always caught in early childhood, we now understand that sucrose intolerance may affect a more significant percentage of the population even into adulthood, and may account for chronic digestive symptoms that have been incorrectly attributed to other conditions, such as irritable bowel syndrome (IBS).

The inability to digest sucrose properly usually results from genetics. However, sucrose intolerance can also result from inflammation or infection of the small intestine. In these situations, treatment of that illness – for example treatment of small intestinal infection with antibiotics, or the treatment of celiac disease with a gluten free diet – can restore normal levels of sucrase isomaltase.

How do we diagnose sucrose intolerance?

Often, it is our dietitians who will suggest that you be tested for sucrose intolerance based on a detailed food and symptom history. To confirm the diagnosis, we can order a 13C-sucrose breath test that you can complete un our office under medical supervision or at home on your own. During this non-invasive test, you will consume a solution containing a modified form of sucrose and breathe into a bag 30, 60 and 90 minutes afterwards. The lab will assessing the chemistry of the air you exhaled during the test and can quantify the amount of sucrase isomaltase enzyme activity your body has.

Another way to diagnose sucrose intolerance is by taking biopsies (tissue samples) of the small intestine during endoscopy. While this is more invasive than breath testing, it has the added advantage of measuring enzyme activity for sucrase isomaltase as well as other digestive enzymes produced in the same region, including lactase (to digest milk sugar) and maltase (to digest starches). If more than one food intolerance is suspected, or the diagnosis is uncertain, this diagnostic approach may be favored.

How do we manage sucrose intolerance?

If there is an underlying non-genetic cause, we treat that cause, but in most people, there is no way to restore normal levels of the sucrase isomaltase enzyme. If you have received a sucrose intolerance diagnosis, you will likely be treated through some combination of supplemental enzyme use and diet change. A prescription enzyme supplement is available and should help you comfortably tolerate sucrose-containing foods when dosed properly before a meal. Since the enzyme needs to be refrigerated, however, some people find it doesn’t always travel well. For this reason, many people with sucrose intolerance find that they sometimes need to adapt their diet to avoid sucrose-containing foods when enzyme supplementation is not convenient.

Our expert GI dietitians will help you understand what foods contain sucrose, how to read food labels on a low sucrose diet, which sweeteners are likely to be safe and well tolerated, and how to navigate eating when you are not able to use your enzyme supplement.

If you have sucrose intolerance, consuming sucrose will be uncomfortable but it is not dangerous – it does not cause long-term damage to the intestine.