What is Congenital Sucrase-Isomaltase Deficiency (CSID)?

by | Jan 15, 2019 | Nutrition | 10 comments

I attended a three day GI conference at the University of Michigan in September. It was an amazing conference packed full of presentations from some of the best GI doctors and dietitians. One presentation was on a topic I had never heard of, so I was intrigued and ready to learn more about it.

​Congenital Sucrase-Isomaltase Deficiency (CSID) is a rare disorder that causes individuals the inability to digest certain sugars due to an absence or low levels of two digestive enzymes, sucrase and isomaltase. Both of these enzymes are involved in the digestion of sugar and starch. Table sugar is broken down into glucose and fructose with the help of the sucrase enzyme. Isomaltase is one of the several enzymes that help digest starches.

Both sucrose (found in fruits, and known as table sugar) and maltose (sugar found in grains) are disaccharides, which means they are made of two simple sugars. During digestion, intestinal enzymes break these down into simple sugars called monosaccharides. Sucrose=glucose + fructose and maltose=glucose + glucose. An individual with CSID has difficulty breaking down the disaccharides into monosaccharides that the body uses for fuel. These disaccharides are too large to be absorbed in the intestines by the microvilli (known as the brush border).

Starch can be a simple or complex carbohydrate. Simple carbohydrates have one or two sugar molecules, and complex carbohydrates have three or more sugars linked together.

Multiple enzymes are needed to properly digest starch. Digestion begins in the mouth with an enzyme in the saliva called amylase. Digestion continues in the stomach by further breaking down the food. In the small intestine, starch is processed by an enzyme called pancreatic amylase and converted into maltose and sucrose. The brush border contains numerous enzymes (sucrase, lactase, maltase) to continue the breakdown of digested food into smaller particles that can be better absorbed. The isomaltase enzyme breaks the bonds linking sugars into glucose, which can’t be broken down by amylase or maltase. This is one of the final steps in the digestion of starch to glucose.

To sum it up, those with CSID lack the sucrase and isomaltase enzymes to properly break down the food to a simpler form, so the body can absorb it.

Without the proper enzymes, digestion can’t take place correctly and individuals can have symptoms, such as:
-Chronic Diarrhea
-Abdominal Pain
-Abdominal Distention
-Excess Gas
-Weight Loss
-Acid Reflux

So, what do you do if you suspect you have CSID?
Visit sucroseintolerance.com to take their quiz. On that site there is also an “ask your doctor” form to take to your physician. A sucrose breath test can help with the diagnosis. This can be ordered by your doctor or I can order a complimentary sucrose breath test to be sent to your home.

What if you have a positive breath test?
You will do a two-week elimination diet of sucrose and starch, followed by a gradual reintroduction of both. The reintroduction will help identify how much of these foods you can tolerate. Many like the guidance of a dietitian familiar with this deficiency to help them navigate through the elimination and reintroduction phases. Others also do the diet along with a test of the sucrase enzyme, Sucraid® (sacrosidase) Oral Solution. The sucrase enzyme can be purchased through One Patient Services, a subsidiary of QOL, Medical, LLC, the manufacturer of Sucraid® Oral Solution, at SucraidASSIST.com.

Please consult with your doctor regarding your symptoms and for a final diagnosis.

If you have any questions regarding Congenital Sucrase-Isomaltase Deficiency, please feel free to call or text me at 410-963-4782 or email at [email protected].

Meet Valerie

Registered Dietitian Nutritionist - CDN, RDN

My name is Valerie Polley. I am a Indianapolis-based registered dietitian and owner of Blue Tree Nutrition. I consult with clients both local and far away.
I have a bachelor’s degree in nutrition from Purdue University and I have been practicing for 20 years.
I thoroughly enjoy helping clients through their gut health journey. I see a range of GI issues including, but not limited to celiac disease, IBS and SIBO. I also specialize in the FODMAP elimination diet.

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