Why Sucraid doesn’t help with starch digestion can be a confusing topic, especially for SI deficiency patients who have tried Sucraid and still experienced symptoms. Many times, symptoms persist because Sucraid cannot break down starch. Sucraid only replaces one specific step in carbohydrate digestion, the breakdown of sucrose.
To understand why Sucraid can’t help digest starch, we first need to look at what Sucraid is meant to do. Sucraid is a solution that contains the enzyme sacrosidase, which is a yeast-based enzyme that mimics the function of the sucrase enzyme so sucrose can be digested properly. However, it does not mimic the function of isomaltase, which is also deficient in many people with CSID or GSID. Sucrose is a complex sugar that is made up of glucose and fructose. When we eat sucrose, the sucrase enzyme breaks it down into glucose and fructose and these simple sugars are small enough for the body to absorb. However, sucrose is too big to be absorbed before it’s broken down, which is why a deficiency in the enzyme causes the symptoms most of us have experienced. Overall, when Sucraid mimics the function of sucrase and allows the body to break down sucrose into simpler monomers, glucose and fructose, it does two things. First, it allows you to efficiently utilize the sugar as energy. Second, it stops those larger sugars from irritating your digestive system because they’re actually broken down and subsequently absorbed as nutrients before they can cause issues.
Simply put, starch digestion is a different pathway and sucrase is not involved. Starch is digested by multiple enzymes that work together - one of which is isomaltase. Starch digestion starts in your mouth and is broken down further in the small intestine by multiple enzymes in specific sequences. Starch is also an extremely complex carbohydrate, even compared to sucrose. If sucrose is like two lego blocks stuck together, starch is like a lego building made of hundreds of legos. It’s a lot more complicated to separate every part of starch because sucrose hydrolysis (breakdown) is a single reaction - like pulling the two legos apart. Digesting starch is more like taking the entire lego building apart brick by brick. This reason alone is a large part of why it’s much harder to therapeutically replace the enzymes in starch digestion.
It’s also important to note that sucrase and isomaltase cleave bonds on different molecules even though their active sites are housed within the same enzyme, which can be confusing. I like to think of Sucrase and Isomaltase as a two-car garage. Both sides of the make up the larger “garage”, but each side has a separate function - both store a different car. Sucrase’s function is to cleave sucrose and isomaltase cleaves limit dextrins. Limit dextrins are byproducts of starch digestion that are similar to complex sugars like sucrose, but are not broken down by sucrase. This is why Sucraid can’t digest starch, why starch can still cause symptoms for many people taking Sucraid, and why the manufacturer of Sucraid recommends eliminating starch when trialing the medication to see how well it works.
This means that even with Sucraid, dietary management is still required to manage symptoms if you notice that starch is problematic for you or your child. It also means that symptoms from starch maldigestion can still persist when taking Sucraid if starch load is not adequately reduced.
One of the most unfortunate misunderstandings around Sucraid is the difference between “Sucraid doesn’t work” and “starch is still causing symptoms.” When Sucraid doesn’t work, there is a functional failure of either the enzyme itself or the way it was stored and administered. When starch is still causing symptoms, Sucraid did what it was supposed to, but starch maldigestion continues irritating the digestive tract. Many people have mistaken “starch is still causing symptoms” as “Sucraid doesn’t work” and given up on trying Sucraid. This distinction is important, because it changes how Sucraid should be evaluated and helps prevent people from dismissing a therapy that may still be working as intended.
Sucraid is designed to replace one specific step in carbohydrate digestion - the breakdown of sucrose. Starch digestion follows a completely different pathway that involves multiple enzymes, including isomaltase, which Sucraid does not replace. Understanding this distinction helps explain why symptoms can persist and allows for a more accurate evaluation of how well Sucraid is working.