Choosing Your Foods

A Basic Dietary Guide for People with CSID

Every case of Congenital Sucrase-Isomaltase Deficiency (CSID) is unique, so no one diet is appropriate for all CSID individuals. People with CSID may need to work with their physician and a registered dietitian to develop an individualized diet plan to meet their specific needs. In general, dietary treatment, when necessary, may need to be combined with therapeutic treatment to focus on restricting the consumption of sugar (sucrose) and starch (isomaltose and maltose). The degree of restriction an affected individual needs is specific to each person.

Keeping food logs or food diaries is an important part of dietary planning for individuals affected by CSID. All foods and beverages consumed should be recorded. The food log should include the time the food was consumed, what food was consumed, details about the food and how it was prepared, and how much food was consumed (for example, ½ cup, 8 ounces, 2 tablespoons). Symptoms, such as bloating, gas, diarrhea, or abdominal pain, should also be recorded. The time of symptom onset and the duration of the symptoms should be recorded as well. A food and symptom log helps you and your registered dietitian identify trigger foods, and thus is an aid in developing an appropriate diet that meets your specific needs.

For individuals with more severe symptoms that may require dietary intervention, it is typically recommended that sucrose and starch be completely eliminated from one’s diet for the first two weeks. This is called an “elimination diet.” However, the elimination diet is severe, very hard to follow, and may not be nutritionally complete. Therefore, it should not be followed for more than approximately two weeks without close guidance from a physician or registered dietitian. The elimination diet has two phases: a sugar elimination phase and a starch elimination phase.

Do certain foods cause you to experience gas, bloating, and chronic diarrhea?

Sucrose, known as table sugar or white sugar, is a carbohydrate that is added to many processed foods. Sucrose also occurs naturally in some foods, such as fruits and juices. People with CSID who are not being treated have trouble digesting foods containing sucrose. After the initial two-week elimination diet is completed, sucrose-containing foods are gradually reintroduced into the diet to determine how much sucrose can be tolerated. It is recommended that only one new food be reintroduced into the diet every three to five days before adding the next new food. Symptoms should be closely monitored during this time to help identify foods that trigger symptoms.

Starch, in addition to fiber and sugars, is another type of carbohydrate. Starch is found in grains like wheat, oats, rice, and starchy vegetables like corn, potatoes, beans, peas, and lentils. Breads, cereals, and crackers, including gluten-free breads and crackers, are all foods with a high starch content. Other sources of starch include certain additives such as maltodextrin, a modified tapioca starch.

After the two-week elimination period, it is important to determine starch tolerance by re-introducing starch-containing foods gradually (one new food every three to five days). It is also important to continue recording your food intake and symptoms during this time. If available, disaccharidase assay results (a test that determines how much enzyme activity exists in the small intestine) may be used as an initial indication of general starch tolerance.

Below is a table to assist people with CSID, physicians, and registered dietitians in planning both the elimination diet (low-sucrose, low-starch) and the reintroduction of foods as your level of sucrose and starch tolerance is established. The fruits and vegetables in the “Foods Tolerated by Most” column are the foods allowed during the two-week elimination phase of the diet (low-sucrose, low-starch). The foods in the other two columns are then gradually reintroduced into the diet to determine sucrose and starch tolerance.


Fruits Tolerated by Most People with Sucrose IntoleranceFruits Tolerated by Some People with Sucrose IntoleranceFruits Tolerated by Few People with Sucrose Intolerance
boysenberrieswatermeloncantaloupe (rockmelon)
cranberries, freshgrapefruits
figs, rawhoneydew melons
kiwi fruitsoranges
lemonspassion fruits
papayastangerines (mandarin oranges, clementines)


Vegetables and Legumes Tolerated by Most People with Sucrose IntoleranceVegetables and Legumes Tolerated by Some Sucrose IntoleranceVegetables and Legumes Tolerated by Few People with Sucrose Intolerance
alfafa sproutsedamame soybeansbeets
artichokes, globe*jicamasblack beans
arugulasleeksblack-eyed peas (cowpeas)
asparagus*okrabutternut/buttercup squashes
bamboo shootspumpkinscarrots
bok choysnow peascassavas (yuca)
broccoli*tempehchickpeas (garbanzo beans)
brussels sprouts*tofucorn
cabbages*yellow wax beansgarlic
cauliflower*green peas
chardkidney beans
chicorieslima beans
chivesnavy beans
collard greensonions
cucumberspinto beans
green beanssplit peas
kalesweet potatoes
mung bean sprouts
mustard greens
peppers (red, yellow, and green)
spaghetti squash
yellow squash (summer)
zucchini (courgettes)

*Artichokes, asparagus, broccoli, brussels sprouts, cabbages, and cauliflower can cause gas in all individuals, not just people with Sucrose Intolerance, so consumption of these foods should be monitored closely.


Carbohydrates that are higher in fiber, which slows down the rate of digestion, may be better tolerated than more processed carbohydrates. For this reason, it is recommended that someone affected by Sucrose Intolerance choose whole-grain bread instead of white bread, whole-grain breakfast cereals (made with whole oats, barley, or bran) instead of more processed cereals. It is also recommended that those affected by Sucrose Intolerance choose whole-wheat pasta, quinoa, lentils, brown rice, or wild rice instead of processed grains like white rice. It is important to read food labels carefully because some whole-grain products may have added sugars, including sucrose.

Since the digestion of starch begins in the mouth with salivary amylase (a digestive enzyme), it is important to thoroughly chew starchy foods. The more a food containing starch is chewed, the greater the exposure the starch has to the salivary amylase enzyme, which allows for more starch to be broken down and digested.

Adding fat and protein along with starches may enhance starch tolerance by slowing the digestive process and allowing more time for ingested food to pass through the small intestine and be exposed to digestive intestinal enzymes. For example, when eating a potato, add sour cream, cheese, or butter.

As people with CSID grow older and their digestive tract lengthens, they can most likely increase the amount of starch in their diet.

Meats and Other Sources of Protein

Most individuals with CSID can eat plainly prepared sources of protein, such as beef, pork, lamb, fish, turkey, chicken, and eggs. A plain preparation refers to cooking without breading, sauces, or seasonings. Protein sources can be cooked with butter, oils, salt and pepper. However, many processed meats, such as bacon, sausage, luncheon meat, deli meat, liverwurst, and pâté, are cured with sucrose or have starch fillers and should be avoided. Once your sucrose and starch tolerance levels have been established, these food items may be reintroduced (one new food every three to five days).

Nuts and nut butters can be a great source of calories for an individual with Sucrose Intolerance. Some nuts are higher in sucrose and starch, however, and should be avoided initially. Nuts and nut butters that are generally tolerated include almonds, Brazil nuts, hazelnuts, macadamia nuts, peanuts, pecans, pumpkin seeds, flax seeds, almond butter, and peanut butter. Legumes and beans are high in starch and should be avoided until your level of starch tolerance has been established. Most individuals with Sucrose Intolerance can tolerate tofu.


Dairy products like cow’s milk, ricotta cheese, plain cottage cheese, sour cream, butter, cream, whipping cream, and hard cheeses (cheddar, Colby, mozzarella, parmesan, provolone, and Swiss) are foods most individuals with CSID can eat. One should inspect food labels and ingredients in processed cheeses or cheese products since these foods may contain sucrose or starch fillers and should be avoided.

Plain, unsweetened yogurt, yogurt sweetened with dextrose, and yogurt sweetened with fructose are dairy products that most CSID patients can tolerate. Many affected individuals choose to eat full-fat dairy products to ensure they are getting enough calories.

A minority of individuals with CSID also have lactose intolerance. Those who are lactose intolerant should consult their physician or registered dietitian to see if milk products can be tolerated.


In general, most fats and oils, such as butter, margarine, olive oil, and vegetable oil, can be tolerated without restriction. With regard to margarines, it is always a good idea to read labels carefully for potential starch or sucrose content. Olives and avocados are high in fat and may be beneficial to those who need to preserve a high calorie intake.


Typically, individuals with CSID can tolerate milk, diet soda, water, and homemade limeade or lemonade made with fresh juice and fructose or dextrose. Many can tolerate regular sodas (non-diet) that are sweetened with high fructose corn syrup. Sweetened sodas should only be consumed under the advice of a registered dietitian or physician.


In general, most people with CSID can tolerate salt and pepper, as well as fresh herbs. However, many spices may contain sugar or starch fillers, so one should read the labels of spices carefully. It may be best to avoid seasonings initially during the two-week elimination diet. Once your sucrose and starch tolerance levels have been established, herbs and spices may be added back to your diet. Remember to only add one new food (herb or spice) every three to five days to best determine your ability to tolerate it.

Other Tips

Parents or caregivers have noticed a few trends that have contributed to raising tolerance levels when adding starch to the diet.

First, thoroughly chew food. For example, chew a bite of starchy food 30 times before swallowing. Salivary amylase is the first enzyme to break down starch, so starchy foods break down more easily if exposed to salivary amylase in the mouth for an extended period. The more a food is chewed, the greater the exposure of the starchy food to this digestive enzyme.

Second, the combination of a high-starch food with a fatty food at the same time of ingestion assists in digestion; for example, combining cheese with a starchy vegetable. The amount of time an ingested food spends in the small intestine affects starch digestion. Foods with a high-fat content are processed more slowly and allow the starch to have more exposure to the pancreatic enzyme amylase, isomaltase, and maltase-glucoamylase in the small intestine.

Working with a registered dietitian who has experience with Sucrose Intolerance is crucial for dietary success. Registered dietitians are able to demonstrate how to effectively write and manage a food log or diary and how to add foods to the diet. They can also use their networks of fellow registered dietitians who may have experience with low-sucrose diets. At first, the list of food choices for someone with Sucrose Intolerance may seem very limited, but rest assured that, over time and close monitoring of specific foods and related symptoms, the list of acceptable foods you can tolerate will grow substantially.

Sucrose Intolerance May Be More Common Than You Think