Lifestyle and Wellness for Patients and Families living with Glycogen Storage Diseases

Nutrition Guidelines for Glycogen Storage Disease Type I

Glycogen Storage Disease Type I (GSDI) is a genetic metabolic disorder of the liver. GSD I causes the inability of the liver to breakdown glycogen to glucose which the body uses as its main source of fuel. Glycogen is a stored form of sugar in the body. As a result of the inability to breakdown glycogen, patients with GSD are at risk for low blood sugars (hypoglycemia) during periods of fasting (i.e. between meals).

The following is a recommended general nutrition guideline for those with GSDI to help maximize blood sugar and lactic acid control, nutrition, and energy.



All carbohydrates are classified as complex carbohydrates or simple sugars. Complex carbohydrates take longer to digest than simple sugars and include foods such as breads, cereals, grains, rice, pasta, crackers, beans (garbanzo, pinto, kidney for example). The combination of taking cornstarch and eating complex carbohydrates with each meal is important to maintain appropriate blood sugar levels. However, complex carbohydrates should be avoided if they contain added sugar, dried fruits and honey.

Read the food label on each package to find brands with the lowest sugar content (i.e.preferably less than 5 grams per meal).

Simple sugars include:

Glucose, Galactose (dairy sugar), Lactose (galactose + glucose), Fructose (fruit sugar) and Sucrose (fructose + glucose).

When a person has GSDI, the enzyme that converts galactose and fructose to glucose is defective. This means that glucose can immediately be used by the body, but any sugar containing fructose or galactose cannot be used by the body. Instead, galactose and fructose are converted to unwanted glycogen stores, lactic acid, fatty acids, and uric acid which can be harmful to the body in large quantities.

Therefore, patients with GSD Type Ia or Ib should not consume foods that contain fructose and galactose as the goal is to try to limit the amount of non-usable sugars at all times.

Our team’s recommended diet allows small amounts of fructose and galactose to be consumed in order to diversify the diet and improve nutrition, but it is important to keep the amount of fructose + galactose to less than 2.5 grams per meal.

Table 1. List of sugars that are and are not allowed for the GSDI diet.


Sugars allowedSugars Not Allowed



Dextrose Dextrin

Agave Syrup

Fructose (natural sugar found in fruit), also a component of sucrose



Galactose (a component of lactose), Lactose (sugar found in milk)
Corn Syrup Aspartame (Nutrasweet, Equal) Acesulfame K (Sunett, Sweet One)

Saccharin (Sweet’N low, Sugar Twin)

Stevia Sucralose (Splenda)

Truvia Barley Syrup

Brown Rice Syrup


High Fructose Corn Syrup Brown Sugar

Invert Sugar

Powdered Sugar, Confectioners’ Sugar Maple Syrup

Molasses Raw Sugar Sorghum

Sorbitol (Sugar Alcohol) Sugar Beet


Tapioca Syrup
Mannitol, Isomalt (Sugar Alcohol)
Xylitol (Sugar Alcohol)

Foods and the Type of Sugar Each Contain

Fruits contain fructose. Many fruits contain significant amounts of fructose and should be avoided. If fruit is consumed, it should be consumed in very small amounts and should not be consumed in a meal that includes foods that contain galactose.


Most vegetables are low in sugar and low in calories. However, it is necessary to avoid using more than 2 packets of ketchup at a time and limiting tomato/marinara sauces on foods to no more than ¼ cup per meal because of the fructose in the tomato (remember tomatoes are actually classified as a fruit). Vegetables provide many nutrients and vitamins that we all need and should be included in the diet of every GSD Type I patient.


With GSD I we recommend to avoid dairy products as much as possible. If milk must be consumed, it is suggest to limit the intake to 2 oz or less per day. Cow’s milk may be appropriately substituted with enriched soy milk (Silk Soy, Eden soy or West Soy plus) or rice milk; however, it is important to be aware of how much sugar is in soy milk. Even some “Plain” soymilks contain added sugars, making them inappropriate for a person with GSD I to consume. Therefore the best type of soy milk to buy is the “Plain, unsweetened” or soy milk that is sweetened with an artificial sweetener.

As a result of the recommended limited intake of milk and dairy, calcium and vitamin D deficiency is likely to occur without adequate substitutions. Please refer to the section titled “Multivitamins and Calcium Supplementation for suggestions on calcium supplements.


Most plain meat dishes are low in sugar. Avoid meats cooked in sweet sauces. It is best to cook meats using low-fat methods such as broiling, baking, grilling, steaming, and stir frying (without oil).


Dietary fat should be limited to 20-30% of total daily calories with equal distribution between monounsaturated, polyunsaturated, and saturated fats. Cholesterol should be limited to <300 mg/day. It is also encouraged to consume fish, especially oily fish, at least twice a week. Check with your dietitian to determine if your child is meeting these recommendations.


Those that contain fructose, lactose, or sucrose should be avoided. Choose unsweetened beverages such as unsweetened tea or sugar-free beverages such as crystal light, sugar-free soft drinks, or any type of artificially sweetened lemonade, Kool- aid, or fruit punch.


This article is an extract from General Nutrition Guideliness for GSDI – Katalin Ross, RD, LDN at University of Florida. Full link here


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