What foods should be avoided with CSID?

October 4, 2025 •

4 min read

Congenital Sucrase-Isomaltase Deficiency (CSID) is a rare genetic disorder affecting the ability to digest sugars like sucrose and starches. This enzymatic deficit leads to significant gastrointestinal distress, making a specialized diet necessary. Understanding what foods should be avoided with CSID is paramount for managing symptoms and maintaining nutritional health.

Quick Summary

CSID is a genetic digestive disorder caused by an inability to break down sucrose and starch. This article details the specific high-sucrose and starchy foods to eliminate or restrict, highlighting the importance of reading labels and personalizing your diet to control symptoms.

Key Points

Avoid Sucrose: Eliminate table sugar and processed foods with added sucrose to control symptoms, as the sucrase enzyme is severely deficient.
Limit Starch: Be cautious with grains and starchy vegetables, as tolerance levels vary between individuals and require careful testing.
Read Labels Carefully: Hidden sucrose (cane sugar, maple syrup, etc.) and starch fillers are common in processed meats, sauces, and spices.
Test Individual Tolerance: Introduce potentially tolerable starchy foods slowly and in moderation after a period of elimination to determine your specific limits.
Consult a Professional: Work with a dietitian experienced in CSID to develop a balanced meal plan that avoids malabsorption while ensuring proper nutrition.

Understanding CSID and Dietary Needs

Congenital Sucrase-Isomaltase Deficiency (CSID) is a genetic condition stemming from a mutation in the sucrase-isomaltase (SI) gene. This deficiency impairs the body's ability to produce or properly utilize the digestive enzymes sucrase and isomaltase in the small intestine. These enzymes are crucial for breaking down disaccharides like sucrose and maltose, as well as starches, into simple, absorbable monosaccharides. When these carbohydrates are not properly digested, they pass into the large intestine where they are fermented by bacteria, leading to a host of uncomfortable and often debilitating gastrointestinal symptoms.

Why Sucrose and Starch are Problematic

The fermentation process caused by malabsorption creates gas, organic acids, and other molecules that cause bloating, abdominal pain, and watery diarrhea. The severity of symptoms can vary widely depending on the individual's residual enzyme activity and the amount of sucrose and starch consumed. Children with CSID often experience more severe symptoms and are at risk for failure to thrive and malnutrition, making strict dietary management critical from an early age.

High-Sucrose Foods to Avoid

Sucrose is commonly known as table sugar, but it's found in many foods, both natural and processed. For many with CSID, these items must be completely eliminated.

Fruits High in Sucrose

Apples
Apricots
Bananas
Cantaloupe and Honeydew Melon
Dates and Figs
Oranges (Mandarin, Clementine)
Peaches and Pineapple

Sweeteners and Processed Sugars

Table sugar, brown sugar, powdered sugar
Maple syrup and molasses
Honey and agave syrup, depending on individual tolerance
Cane sugar, beet sugar, and coconut sugar

Sweetened Beverages and Desserts

Sweetened juices and flavored waters
Regular sodas and energy drinks sweetened with sucrose
Flavored milks and yogurts
Ice cream, sorbet, and frozen yogurt
Cakes, cookies, pastries, and biscuits with added sugar

Starchy Foods to Restrict or Avoid

Starch tolerance is highly individual and can improve with age. An initial strict low-starch diet is often recommended, followed by a gradual reintroduction to determine personal tolerance levels.

Grains and Grain-Based Products

Breads and pasta made from refined flour
Cereals with added sugar
Crackers and most processed grains
Rice and oats, particularly in large quantities

Starchy Vegetables and Legumes

Potatoes (white and sweet) and yams
Corn (and popcorn)
Peas (green and split peas)
Legumes, including beans, lentils, and chickpeas
Butternut squash, beets, and parsnips

Hidden Sources of Sucrose and Starch

Many processed and pre-prepared foods contain hidden sucrose or starch fillers that can trigger symptoms. Careful label reading is essential.

Processed Meats: Deli meats, sausages, and bacon often use sucrose or starch fillers as curing agents.
Condiments and Sauces: Barbecue sauce, ketchup, and many salad dressings are loaded with hidden sugars and starches.
Spices and Seasoning Blends: Some pre-mixed spice blends can contain anti-caking agents that are starch-based or include sugars.
Processed Dairy: Flavored yogurts, ice cream, and American cheese slices can contain starches and sugars.

The CSID Diet: A Framework for Eating

While a restricted diet may seem daunting, a wide variety of foods are typically well-tolerated. The key is focusing on whole, unprocessed items and carefully testing your personal tolerance levels. Protein sources like plain meats, poultry, and eggs are generally safe. Unsweetened dairy and alternatives are often suitable, as are healthy fats from oils and avocados. Many low-sucrose fruits like berries and certain melons, and non-starchy vegetables such as leafy greens, are also excellent choices.

Sucrose vs. Starch Tolerance in CSID

Individual tolerance to carbohydrates varies, but there are some general trends regarding sucrose and starch. This table compares the typical experience with each.


Feature	Sucrose Malabsorption	Starch Malabsorption
Symptom Severity	Generally causes more severe symptoms due to complete lack of sucrase enzyme.	Can cause symptoms, but often less severe due to other enzymes assisting with digestion.
Enzyme Replacement	Sacrosidase (Sucraid®) is an effective prescription treatment to aid in sucrose digestion.	No specific enzyme replacement is available for starch, so management relies on dietary modification.
Improvement with Age	Some children may develop a better tolerance to sucrose over time.	Tolerance to starches typically improves with age as the digestive tract lengthens.
Dietary Restriction	Often requires a lifelong adherence to a strict, sucrose-free diet.	Starch restriction can sometimes be relaxed over time based on individual tolerance.

Reading Food Labels for CSID

Mastering label reading is crucial for successful CSID management. Be vigilant for various terms indicating sucrose or hidden starch. Look for ingredients such as cane sugar, high-fructose corn syrup, honey, maple syrup, corn syrup solids, and maltodextrin. A helpful resource for identifying additives and building a personalized diet is provided by CSID Cares: https://www.csidcares.org/treatment/diet/.

Conclusion

Navigating a CSID-friendly diet requires diligence and a personalized approach. By understanding what foods should be avoided with CSID, particularly high-sucrose and high-starch items, and learning to read labels meticulously, individuals can significantly reduce symptoms and improve their quality of life. Regular consultation with a healthcare provider and a registered dietitian experienced with CSID is recommended to ensure nutritional needs are met while maintaining symptom control. With careful management, a balanced and healthy diet is achievable.

Frequently Asked Questions

Sucrose intolerance is typically more severe in CSID because the body lacks the specific sucrase enzyme to break it down. While the isomaltase deficiency affects starch digestion, other enzymes can help, meaning some starch may be better tolerated than sucrose, and starch tolerance can improve with age.

Yes, but they must be selective. High-sucrose fruits like apples, bananas, and mangos should be avoided. Lower-sucrose fruits like berries, melons, and citrus fruits are often better tolerated, but individual reactions can vary.

Not necessarily. Grains and starches often have variable tolerance. Many people with CSID start with a low-starch diet but may reintroduce certain whole grains like quinoa or oats in small, well-chewed portions over time to test their tolerance.

Always read the ingredient list. Look for terms like sugar, cane sugar, brown sugar, maple syrup, molasses, or dark corn syrup, which are all sources of sucrose that should be avoided.

Safe options include unsweetened natural yogurt with low-sucrose fruits like berries, gelatin or sugar-free jelly, and desserts made with alternative sweeteners like Stevia or dextrose.

Thorough chewing is key to allowing salivary amylase to start breaking down starch. Additionally, combining starches with fats, like adding sour cream to a potato, can slow digestion and increase the time available for enzymatic breakdown.

No, it is a treatment for sucrose malabsorption, not a cure. Sacrosidase (Sucraid®) helps digest sucrose but does not correct the maldigestion of starch.