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Nutrition corner

Calcium and GSD

Osteoporosis can be problematic in all types of GSD due to low calcium intake, low vitamin D concentrations, or abnormal bone formation in the setting of acidosis. It is therefore critical to ensure that all people with GSD consume an adequate amount of calcium daily. For people with GSD type I, this is particularly difficult due to the restriction in dairy intake. It is usually necessary to obtain the calcium the body needs through supplementation and/or through the intake of calcium fortified cereals, breads, and calcium-fortified soy milk or rice milk.

How much do we need?

Below are the recommended intakes of calcium based on age, according to the Dietary Reference Intakes for Calcium. (1)

AgeAmount (mg)/day
0-6 months210
7-12 months270
1-3 years500
4-8 years800
9-18 years1300
19-50 years1000
51 and older1200
Pregnant/Lactating Women <181300
Pregnant/Lactating Women >181000

Calcium supplements

There are many different types of calcium supplements to choose from including calcium citrate, calcium carbonate, calcium acetate, calcium gluconate and calcium lactate. There are also non-traditional calcium supplements from oyster shell, bone meal, or dolomite, but these should be avoided as they may contain higher amounts of lead or other toxic metals. (2)

Guide to maximizing calcium supplementation

  • The body absorbs the calcium best when it is taken several times a day, in amounts lower than 500 mg at a time.
  • Most calcium supplements are absorbed better when taken with food.
  • Each calcium supplement differs in the amount of “elemental” calcium (the actual amount of calcium in the supplement) it contains, so one should read the label to determine how much of the supplement is needed
  • Calcium should not be taken with an iron supplement, as calcium interferes with iron absorption.
  • Vitamin D plays a major role in the absorption of calcium and it is very important to make sure enough vitamin D is obtained through dietary sources. Come to Florida in winter to maximize your vitamin D.

Some calcium supplement suggestions

  • Calcium Citrate (most commonly recommended by Dr. Weinstein)
  • Calcium Carbonate
  • Tums EX (sugar-free are available)
  • CalQuick by Twin Labs (liquid formulation)
  • UpCal D by Global Health Products (powder formulation)
  • Calci-Mix by Watson Pharmaceuticals


  • (1) Food and Nutrition Board, The Institute of Medicine, National Academy of Science, 1997.
  • (2) National Osteoporosis Foundation.

Protein and GSD

What is protein?

Protein is a macronutrient (like carbohydrate and fat) that is required for proper growth and development. It serves as the building blocks for our cells, and is also necessary to make antibodies which help our bodies fight off illnesses. In addition, proteins make up hormones, enzymes, and even our DNA. With certain types of GSD (especially types 0, III, VI, and, IX), it is very important to ensure that you have adequate protein intake.

What are sources of protein?

The highest sources of protein come from animals, especially meats, dairy and eggs. Some protein, however, comes from plants, but vegetarians with GSD must work to achieve adequate protein intake. Other sources of protein include all dairy products, all meats, soy milk, tofu, cooked or baked beans (garbanzo, pinto, kidney, white, black eyed peas, split peas), peanut butter, and the different types of nuts. Most protein sources, with the exception of dairy products and cooked dried beans contain little amounts of carbohydrates.

How much protein is required?

Each age group has a certain recommended daily allowance of protein, or RDA, as shown below:

CategoryAge (yrs)Grams of protein per kg body weight per day

Patients with muscle forms of GSD benefit from a high protein diet. For patients with type III GSD, 3-4 grams of protein per kilogram of body weight is recommended daily. Types 0, VI, and IX also need to consume more protein than the RDA (at least 2-3 grams protein per kilogram). It is recommended that patients with types Ia and Ib receive the RDA of protein, but excessive amounts of protein should be avoided.

How do I know how much protein I am getting?

Use the table below as a guideline:

Food Source Grams of protein per kg body weight per day
3 ounces meat (1 medium pork chop,

1 small hamburger, 1/2 of a whole

chicken breast, 1 unbreaded fish filet)

21 grams

1 ounce cheese (the size of a 1-inch cube or 4 cubes the size of dice)

6 grams

1/2 cup cooked dried beans, peas, or lentils

7 grams

1 large egg

6 grams

1 tablespoon of peanut butter

4 grams

1 container of yogurt

7 grams

1/4 cup peanuts

9 grams

1/2 cup Tofu

7 grams

Helpful tips on how to add extra protein for patients with types 0, III, VI, and IX:

  • Add extra cheese to casseroles
  • Use cream sauces or cream soups
  • Incorporate meats into meatloaf, stews, casseroles, burritos, pizzas
  • Use nuts and peanut butter in cookies
  • Add powdered milk to baked goods
  • Use milk to cook hot cereals
  • Offer milk-based puddings and custards
  • Consider adding a protein supplement
    • Carnation Instant Breakfast mixed with 8 ounces milk has ~13 grams protein
    • Beneprotein (protein powder) contains 6 grams protein in 1 scoop or 1 packet
    • Ensure, Boost, and other ready-made nutritional supplements usually contain about 7 grams protein per 8 oz
    • Many also come in the “High Protein” or “Plus” variety which offers more protein

The truth about sugar alcohols

Those with GSD types Ia and Ib have dietary restrictions on sugar consumption, particularly the consumption of fructose, galactose, and sucrose. Because sucrose is restricted, it is encouraged for our GSD Type Ia and Ib patients to consume sugar-free foods and beverages. Many of these sugar-free foods and beverages have artificial sweeteners added, mostly in the form of sugar alcohols (or polyols). Therefore, the goal of this article is to help explain what sugar alcohols are, what they do, and discuss issues with consumption of sugar alcohols in GSD.

What are sugar alcohols?

Even though their chemical make-up partially resembles a sugar and an alcohol, the name is a misnomer, and they are neither a sugar nor an alcohol. They are actually considered a carbohydrate, but they aren’t digested completely in the body. (1)

Some very common types of sugar alcohols are sorbitol, xylitol, mannitol, maltitol, lactitol, eryhtritol, isomalt (note that most sugar alcohol names end with –ol). You may also see the term “Hydrogenated Starch Hydrolysates” (HSH), which is a type of sugar alcohol. (1)

What do they do?

They are mostly used to add a sweet flavor to foods, in place of sugar. They also add bulk or texture to foods and help retain moisture. In addition, sugar alcohols do not turn brown when they are heated. (1)

Should they be consumed in GSD Type Ia and Ib?

Due to their incomplete absorption in the body, they do not cause a rise in the blood glucose concentrations as most carbohydrates do. Since they have limited absorption, the sugar alcohol does not enter the metabolic pathways that are affected by GSD Ia and Ib.

Sorbitol is an exception, however. Our body changes sorbitol to FRUCTOSE during digestion. Therefore, if you have type Ia and Ib, please limit and/or avoid foods that have sorbitol listed in the ingredients.

It should also be noted that very high intakes of sugar alcohols may have a laxative effect (this warning may actually be listed on the food or beverage package).


  • (1) Sugar Alcohols Fact Sheet. Sept 2004. http// .


Vitamins and minerals are an important part of a daily diet. Proper intake of these critical nutrients allow for better growth and overall health. While it is possible to obtain them through foods, it is difficult to achieve sufficient intake on the GSD diet. As a result, all people with GSD should take a multivitamin (MVI).

Each vitamin and mineral plays a very important role in physiologic functions in the body. For example, vitamin A is necessary for vision; Vitamin C is important in the normal development of cartilage and bone, wound healing, and enhancing the absorption of iron; the B vitamins play a large role in the metabolism of nutrients; Vitamin D is critical for bone health, and there are also many other vitamins which have an important role in maintenance, growth, development, and reproduction. For adult women with GSD, it is critical to ensure appropriate folate (folic acit) intake since it is essential for early fetal development.

Please note these important tips when taking your MVI

  1. A multivitamin is more easily absorbed when taken with a meal. This is because the pill dissolves more thoroughly as the full stomach slowly empties and digests food, allowing for easier absorption of the nutrients in the MVI.
  2. Taking a MVI with a meal also reduces the chance of getting an upset stomach.
  3. Look for the letters "USP" on the label. This stands for "United States Pharmacopeia," which ensures the MVI meets standards for potency and purity and that the MVI has been tested to disintegrate and dissolve.
  4. Many MVI contain 100% of the RDA (Recommended Dietary Allowance) for many vitamins and minerals; additional supplements usually do not prove beneficial.
  5. A MVI will NOT provide 100% of daily calcium needs, and a separate calcium supplement is needed to meet calcium needs. This is particularly important for those patients with GSD Type Ia and Ib who cannot consume dairy products. See the Spring 2007 Gator Glycogen Gazette for more on calcium.
  6. Look for a "Complete" MVI. The word "complete" indicates that it contains Iron, as some MVI do not.

Some MVI suggestions are below:

  • One-A-Day (sugar-free, children's and adult varieties available) or generic equivalent
  • Flinstone's Complete (sugar-free available)
  • Poly-Vi-Sol (for the infant)

Carbohydrates and GSD

Carbohydrates are made up of fiber, starches and sugars and make up about 50-60% of the calories that we eat on a daily basis. Complex carbohydrates take longer to digest than simple carbohydrates, but they provide many important vitamins, minerals, and fiber. Simple carbohydrates are also referred to as "simple sugars" and include glucose, galactose (dairy sugar), lactose (galactose + glucose), fructose (fruit sugar) and sucrose (fructose + glucose).

When a person has GSD type I, the enzyme that converts galactose and fructose to glucose is deficient or missing. This means that any food containing fructose, galactose, lactose, or sucrose should be avoided since it cannot be converted to glucose. In addition to causing increased storage of glycogen, the non-utilizable sugars enter alternative pathways causing an increase in lactic acid, triglycerides, and uric acid.

In GSD types III, VI and IX, galactose and fructose can be converted in the body to glucose. In small quantities, these sugars do not cause harm, but foods high in sucrose and/or fructose should be avoided since it will lead to over storage of glycogen. The increased glycogen formation can worsen hepatomegaly, and it may contribute to increased damage of the muscles in the glycogen storage diseases that also affect the muscle. In addition, simple sugars increase insulin production which, in turn can cause a rapid fall in glucose concentrations and hypoglycemia.

In GSD type O, the inability to store sugars as glycogen results in increased lactate accumulation following consumption of simple sugars. The slow release of sugars in complex carbohydrates allow blood glucose concentrations to be maintained without the associated lactic acidosis.

With all GSD types it is important to consume adequate amounts of complex carbohydrates in your diet. Failure to eat sufficient carbohydrates can increase the frequency of hypoglycemia. In addition, lack of carbohydrate intake (as in the Adkins diet) will increase glycogen and/or fat breakdown leading to increased ketone formation (GSD types 0, III, VI, and IX) or lactic acid formation (GSD types I and XI).

Uncooked cornstarch is a complex starch that provides a steady amount of glucose because it is digested at a slower rate than other complex carbohydrates. However, the combination of taking cornstarch and eating complex carbohydrates such as whole grain breads and cereals, grains, brown and wild rice, whole wheat pasta, crackers, beans (i.e. garbanzo, pinto, kidney), and starchy vegetables with each meal is important to maintain appropriate blood sugar levels. It is just as important to avoid excess intake of simple sugars such as cookies, cakes, pies, candies, doughnuts, ice cream, soda, Kool-Aid, strawberry Hershey's syrup, fruit juices, etc. to help keep the liver and muscles healthy.