Disorder-Specific Survival Kit:
Galactosemia

Galactosemia: An Overview

Dietary Management of Galactosemia

Food Labels
Medicine
Dietary Supplements
Food Lists
Menus and Food Choices

The Genetics of Galactosemia

Resources

Galactosemia: An Overview

Galactosemia is an inherited disorder characterized by an inability of the body to utilize galactose. Galactosemia means "galactose in the blood ". Galactose is a type of food sugar found mainly in dairy products, and is produced within the body as well. The main source of galactose in the diet is milk products. Milk contains a sugar called lactose, and during digestion, lactose is broken down into the sugars glucose and galactose. Glucose can be used as a source of energy by the body, but galactose needs to be further broken down by a specific chemical (enzyme) before it can be utilized.

Persons with galactosemia have very little or entirely lack an enzyme that helps the body break down galactose. There are three different enzyme problems that can lead to galactosemia. This information will focus on the most common type of galactosemia, often called "classic galactosemia". The enzyme that is reduced or missing in classic galactosemia is called galactose-1-phosphate uridyl transferase (GALT). The GALT enzyme enables the body to break down galactose into glucose for energy. Because some individuals with galactosemia have more enzyme than others, the severity and treatment of the disorder can vary.

Galactosemia is treated by removing foods that contain galactose from the diet. Any foods containing lactose, thereby containing galactose, should be avoided. Untreated galactosemia will result in a harmful build-up of galactose and galactose-1-phosphate (a form of galactose) in the bloodstream and body tissues. Infants with unrecognized galactosemia usually have problems with feeding and do not grow as they should. If galactosemia is not treated, infants can develop cataracts, liver disease and kidney problems. In addition, the build-up of galactose and galactose-1-phosphate can cause brain damage, and in some cases, can lead to death. Even with treatment, some children may develop learning disabilities, and girls with galactosemia may have problems with their ovaries. With continued dietary management, however, many individuals with galactosemia enjoy good health, and are able to lead independent lives.

Dietary Management of Galactosemia

The goal of dietary treatment for galactosemia is to minimize galactose intake and thus minimize galactose-1-phosphate production. Galactose-1-phosphate levels are determined by

1) individual internal galactose production
2) the specific allele for galactosemia, and
3) galactose intake from foods.

It is not possible for a person with galactosemia to have a galactose-free diet. However, all persons with galactosemia should limit galactose intake from foods to a very low level. The galactose-1-phosphate levels of the individual determine the degree of dietary restriction necessary.

Because milk and milk products are the most common food source of galactose, persons with galactosemia should avoid these foods. In the past, there was some controversy about how long a person with galactosemia should remain on a galactose-restricted diet. It is now recommended that persons with galactosemia should avoid eating foods with galactose throughout life.

A galactose-restricted diet should keep blood galactose-1-phosphate (gal-1-p) below 3 to 4 mg/100 ml, while containing enough nutrients for normal body function. The diet allows most protein-containing foods other than milk and milk products. Fruits, vegetables, grains, breads, fats and sugars are acceptable, as long as they do not have ingredients that contain galactose. Some fruits and vegetables do contain small amounts of galactose. However, the form of galactose (bound galactose) found in fruits and vegetables is not usable by the body, and may not contribute to elevated blood gal-1-p. Recent research has shown that bound galactose may in fact be usable by the body, but further studies are needed to confirm this.

Food Labels
The labels of all processed foods must be read carefully for ingredients which are milk products. The milk products to be avoided in processed foods are milk, casein, dry milk solids, lactose, curds and whey. The milk proteins casein and caseinate must be limited in the diet. They can provide large amounts of galactose if many foods or large amounts of any food containing casein are eaten. The following products may be used because they do not contain lactose: lactate, lactic acid, lactylates and calcium compounds. Food labels should be checked every time, since the ingredients in food products can change without notice.

Medicine
Lactose is often used as a filler or inactive ingredient in medicines, and might not be listed on the package. The best way to ensure that a medication does not contain fillers with galactose is to ask a pharmacist. They should have access to information about medication ingredients. If possible, have a pharmacist be aware of what medication ingredients are unacceptable to you. This is the most effective way of avoiding galactose-containing medications. Many people develop a standard letter to present to pharmacists that describes galactosemia and the ingredients that should be avoided.   A sample letter is included on this website. (This letter is an Acrobat PDF file. To view it, download Acrobat Reader™ here.)

Dietary Supplements
Dietary supplements should be taken only when recommended by your doctor or health care professional. Federal regulations require that these products be labeled for the percentage of US RDA nutrients; fillers or inactive ingredients are not listed. Because lactose may be used as a filler in some dietary supplements, it is important to check with a pharmacist to ensure a supplement does not contain any hidden sources of galactose.

Milk and milk products are the usual dietary source of calcium. Because persons with galactosemia remove milk products from their diet, they need to add calcium back into their diet through supplements. All people with galactosemia should have a regular daily supplement of calcium either from a soy formula or tablets. Consult your doctor or nutritionist to find out how much calcium supplementation is right for you.

Food Lists  It may be helpful to you to make these lists and laminate them, and carry them in your wallet. A sample wallet card is included on this website.  (This example is an Acrobat PDF file. To view it, download Acrobat Reader™ here.)

Foods high in galactose.  Some foods contain obvious galactose and are unacceptable:

The galactose content of some foods is provided as a reference.

• Hydrolyzed protein found in canned meats or fish may be made from milk proteins, casein or whey, which are unacceptable. If it is unclear on the label the source of the hydrolyzed protein, further investigation is necessary.

• Some legumes (dried beans) contain large amounts of galactose, especially garbanzo beans which are considered unacceptable.

• Fermented soy products (fermented soy sauce, miso, tempe) are not recommended as galactose can be released in the fermentation process.   Non-fermented soy products (tofu, textured vegetable protein, and soybean extract) are acceptable.

Foods with moderate amounts of galactose.  Some foods contain moderate amounts of galactose and are limited as needed to support appropriate galactose-1-phosphate levels.

Foods with more than 10 mg Galactose/100 gram of food:

tomato
date
papaya
bell pepper
persimmon
watermelon

Foods with 5-10 mg Galactose/100 gram of food:

Acceptable foods and ingredients:

Unacceptable ingredients

Menus and Foods Choices
Plain, simple foods are the safest choices for persons with galactosemia because it is less likely that offending ingredients are present. This means less emphasis on commercially prepared foods. Children are more readily able to learn which foods are ‘safe’ and which are not. This makes it easier for them to make choices and be self confident.

The Genetics of Galactosemia

Genes are the basic units of hereditary material. Every cell of our body contains approximately 80,000 genes. Genes contain the instruction code or "blueprint" that directs the development and function of each cell and tissue in the human body. Genes, in turn, are packaged on larger structures called chromosomes. Each chromosome contains several thousand genes.

Genes and chromosomes exist in pairs. Every cell has 23 pairs of chromosomes containing two copies of every gene. Each person received one copy of every gene from their mother in the egg cell, and one from their father in the sperm cell. Most often, genes function properly. In some cases however, a change, or mutation in a gene can cause it to not function. Mutations in certain genes can cause inherited, or genetic disorders.

The gene mutation that causes galactosemia is inherited in what is called an autosomal recessive pattern. This means that a non-working copy of the gene must be inherited from both parents for a child to be affected with the disorder. The parents’ health is not affected because the other copy of the gene is working correctly, and compensates for the non-working copy. Parents of children who have an autosomal recessive disorder are called "carriers" of the disorder. This is because they themselves do not have the disorder, but can have sons and daughters who are affected. It is important to remember that every person carries several non-working recessive genes. Only when both parents carry the same non-working gene is there a chance of having a child with a recessive disorder.

Unfortunately, there is no way for parents to know if they carry the non-working gene that causes galactosemia until they have a child with the disorder.

The chance that two parents who carry the same non-working gene will have a child with a recessive disorder is one in four, or 25% with each pregnancy (see diagram 2). The chance these parents will have a child who is a carrier of the disorder like themselves is one in two, or 50% with each pregnancy. There is also a one in four, or 25% chance that these parents will have a child who is neither affected nor a carrier of the disorder. Both sons and daughters of carrier parents have the same chances of inheriting the genes that cause galactosemia.

The gene that codes for galactose-1-phosphate uridyl transferase (GALT) is located on chromosome 9. Many different mutations within this gene have been identified, and the most common mutation is called "Q188R". Most people with galactosemia have this mutation. A milder form of galactosemia known as the "Duarte variant" is also caused by a mutation within the GALT gene. Different changes within the GALT gene are what lead to variations in enzyme levels between individuals with galactosemia.

Resources

Parents of Galactosemic Children
2871 Stage Coach Drive
Valley Springs, CA 95252
Contact Person: Gayle Dennis
(209) 772-2449
E-mail: gayleds@aol.com

This group’s mission is to maximize the potential for normal development of the individual with galactosemia. Some of the resources they provide are parent support, newsletter, galactosemia literature and dietary information.