Hereditary Fructose Intolerance

What is hereditary fructose intolerance?

Hereditary fructose intolerance is a genetic condition that causes you to be unable to digest fructose (and substances like fructose). Fructose is a natural sugar that’s mostly in fruits.

People with this condition don’t have the enzyme to break down fructose, called fructose-1-aldolase. This causes fructose to build up in your liver and kidneys. Without treatment, this can lead to health conditions like kidney failure and liver failure.

Healthcare providers most often diagnose hereditary fructose intolerance in babies after they begin eating solid foods. It’s possible to receive a diagnosis later in life, too.

What are the symptoms of hereditary fructose intolerance?

People with the condition often don’t like the taste of fruits or sweet foods. Other symptoms could include:

• Not growing as expected (failure to thrive)
• Nausea and vomiting
• Abdominal pain
• Jaundice
• Low blood sugar
• Malnutrition
• Convulsions

If you notice that your child isn’t gaining weight, growing slowly or refuses to eat fruits, talk to their healthcare provider.

What causes hereditary fructose intolerance?

You have hereditary fructose intolerance when your liver can’t produce an enzyme called fructose-1-aldolase due to an error in your genetic code. This enzyme is responsible for metabolizing fructose.

Hereditary fructose intolerance is genetic. It’s an autosomal recessive disorder, which means both biological parents must carry the gene for their child to have the condition. (Just because both parents are carriers doesn’t mean their child will have the disease.)

What are the risk factors for hereditary fructose intolerance?

Since the condition is genetic, having a birth parent with the condition is the largest risk factor. Both parents must have the irregular gene for a child to be at risk of inheriting hereditary fructose intolerance. People who are carriers may want genetic counseling to learn how this disease affects their family.

What are the complications of hereditary fructose intolerance?

Without proper treatment, the disease can cause life-threatening complications. Some of the complications are:

• Kidney damage (which can lead to kidney failure)
• Liver damage (which can lead to liver failure)
• Enlarged spleen
• Gastrointestinal bleeding
• Blood clotting issues
• Growth problems due to malabsorption of nutrients
• Low blood sugar (hypoglycemia)
• Metabolic acidosis

Early diagnosis and treatment can often prevent these serious complications.

How is hereditary fructose intolerance diagnosed?

Healthcare providers diagnose it by performing a physical examination and evaluating your child’s symptoms. This usually happens once you begin giving your child fructose-containing foods.

The following tests can also lead your provider to a diagnosis:

• Blood tests: These tests check liver and kidney function and blood sugar levels.
• Urine tests: These tests check for fructose in your child’s pee.
• Genetic tests: This is a specific test that looks for changes in the fructose-1-aldolase (ALDOB) gene.
• Liver biopsy: Rarely, a biopsy can show the activity of the fructose-1-aldolase enzyme.

While rare, it’s possible to receive a diagnosis in adulthood, especially if your symptoms are mild.

How is hereditary fructose intolerance treated?

There’s no cure for hereditary fructose intolerance. Treatment focuses on completely avoiding foods and drinks that contain fructose, sucrose and sorbitol. Sucrose is made up of fructose. Sorbitol works like fructose in your body, which is why providers recommend eliminating it, too.

Foods to avoid

Eliminating foods that contain fructose (or related sugars) will be the main part of your child’s treatment plan. Some of those foods are:

• Anything that contains high fructose corn syrup (many processed foods)
• Fruits (all fruit contains some amount of fructose)
• Vegetables (some vegetables have very low amounts of fructose)
• Honey, agave nectar, maple syrup and similar sweeteners
• Sugary drinks like fruit juices and soft drinks
• Low sugar or diet foods and beverages that contain sorbitol

Because this can be difficult to manage on your own, your healthcare provider can help you figure out what you/your child can eat. This often involves working with a dietitian who specializes in metabolic disorders.

What can I expect if my child has hereditary fructose intolerance?

You can expect a lot of change and preparation in your child’s — and family’s — daily life. Hereditary fructose intolerance is a lifelong disease that requires careful management. But careful management is possible.

Some ways to manage avoiding all foods that contain fructose, sucrose and sorbitol include:

• Educating your child, family and any caretakers about what contains fructose and related sugars
• Carefully reading labels on food items
• Packing your child’s meals for school and other activities
• Having go-to restaurants that serve food your child can eat
• Deciding if your whole family will follow your child’s dietary restrictions

Over time, you’ll figure out what works best for your child and family. And your child’s healthcare team will be by your side to help you. You may also consider joining a support group to learn from others going through the same thing. Your child can live a healthy life with this disease. They can go to school, participate in activities and live a long, happy life. Work with your child’s healthcare team on a meal plan that eliminates fructose in all forms.

When should I see my healthcare provider?

Contact your child’s healthcare provider if you suspect fructose intolerance, especially if you have a family history of the condition. They can recommend what to do next.

What questions should I ask my provider?

Questions to ask include:

• What foods should my child avoid? Can a dietitian help me?
• Is there any damage to my child’s kidneys or liver so far?
• Will my child live a normal life?
• Will my child pass this on to their child?