Hereditary Fructose Intolerance
What is Hereditary Fructose Intolerance?
Hereditary fructose intolerance is a rare genetic condition that prevents your body from breaking down fructose properly. Fructose is a natural sugar found in fruits, table sugar, and many processed foods. When you have this condition, your liver lacks an enzyme called aldolase B that helps process fructose.
Without this enzyme, fructose builds up in your liver and kidneys. This buildup causes damage to these organs over time. The condition is inherited, meaning you get it from both parents who carry the gene. Most people discover they have it in infancy or early childhood when fruits or sweet foods are introduced.
This is different from fructose malabsorption, which is a digestive issue. Hereditary fructose intolerance is a metabolic disorder that can cause serious liver damage if fructose is not avoided. The good news is that people with this condition can live healthy lives by following a strict fructose-free diet.
Symptoms
- Nausea and vomiting after eating fructose-containing foods
- Abdominal pain and bloating
- Sweating and shakiness after eating sweets
- Poor appetite and failure to thrive in infants
- Yellowing of the skin or eyes, known as jaundice
- Enlarged liver, detectable by a doctor during physical exam
- Low blood sugar levels, which can cause dizziness or confusion
- Strong dislike or aversion to sweet foods and fruits
- Fatigue and weakness
- Developmental delays in young children
Many people with this condition naturally avoid sweet foods because they learn these foods make them feel sick. Infants may show symptoms when formula, fruits, or sweetened foods are first introduced. Some people have milder symptoms and may not be diagnosed until later in life.
Concerned about Hereditary Fructose Intolerance? Check your levels.
Screen for 1,200+ health conditions
Causes and risk factors
Hereditary fructose intolerance is caused by mutations in the ALDOB gene. This gene provides instructions for making the aldolase B enzyme your liver needs to break down fructose. You must inherit a mutated copy of the gene from both parents to develop the condition. People who inherit only one mutated copy are carriers but do not have symptoms.
The condition is present from birth and cannot be prevented. Risk factors include having parents who are both carriers of the ALDOB gene mutation. The condition is rare, affecting roughly 1 in 20,000 to 30,000 people worldwide. Certain populations may have higher carrier rates due to genetic ancestry. There are no lifestyle or environmental factors that cause this condition, as it is entirely genetic.
How it's diagnosed
Hereditary fructose intolerance is diagnosed through a combination of medical history, symptoms, and laboratory tests. Doctors look for patterns like vomiting and low blood sugar after eating fructose-containing foods. Blood tests can show liver damage through elevated liver enzymes like ALT, which rises when fructose damages liver cells. Genetic testing confirms the diagnosis by identifying mutations in the ALDOB gene.
Rite Aid offers blood testing that includes ALT levels, which can help identify liver damage related to fructose exposure. Monitoring ALT levels is important for people with this condition to ensure they are following their fructose-free diet properly and to track liver health over time. A liver biopsy was once used to measure aldolase B activity directly, but genetic testing has largely replaced this invasive procedure.
Treatment options
- Complete avoidance of fructose, sucrose, and sorbitol in the diet
- Reading food labels carefully to identify hidden sources of fructose
- Working with a registered dietitian who specializes in metabolic disorders
- Avoiding fruits, honey, table sugar, and high-fructose corn syrup
- Monitoring liver function through regular blood tests like ALT
- Educating family members and caregivers about safe foods
- Carrying medical alert identification in case of emergency
- Regular follow-up with a metabolic specialist or geneticist
- Nutritional supplements if needed to prevent deficiencies
- Immediate medical care if accidental fructose ingestion occurs
Concerned about Hereditary Fructose Intolerance? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
You must avoid all foods containing fructose, sucrose, and sorbitol. This includes fruits, honey, table sugar, high-fructose corn syrup, and many processed foods. Always read ingredient labels carefully, as these sugars appear in unexpected places like medications, condiments, and baked goods. Working with a dietitian can help you create a safe meal plan.
No, this condition is present from birth because it is genetic. However, some people may not be diagnosed until adulthood if their symptoms are mild or if they naturally avoid sweet foods. The condition itself does not develop over time, but symptoms appear when fructose-containing foods are eaten.
Hereditary fructose intolerance is a genetic metabolic disorder that causes liver and kidney damage when fructose is consumed. Fructose malabsorption is a digestive condition where the intestines cannot absorb fructose properly, leading to bloating and diarrhea. Hereditary fructose intolerance is more serious and requires complete fructose avoidance, while malabsorption may allow small amounts.
Eating fructose causes a buildup of toxic substances in the liver and kidneys. Symptoms include nausea, vomiting, sweating, low blood sugar, and abdominal pain. Repeated fructose exposure leads to liver damage, kidney problems, and potentially life-threatening complications. Strict dietary avoidance is essential to prevent organ damage.
Regular monitoring of liver function is important, typically every 6 to 12 months. Your doctor may recommend more frequent testing if you have had recent symptoms or accidental fructose exposure. Blood tests like ALT help ensure your liver remains healthy and that your diet is fructose-free.
No, children with this condition must avoid all fruits, as they contain natural fructose. This includes fresh, dried, and cooked fruits, as well as fruit juices. Safe alternatives include certain vegetables that are low in fructose and safe starches like rice and potatoes.
There is no cure for this genetic condition. Treatment involves lifelong strict avoidance of fructose, sucrose, and sorbitol. With careful dietary management, people with hereditary fructose intolerance can live healthy, normal lives without complications.
Seek medical attention immediately if you experience severe symptoms like vomiting, confusion, or extreme weakness. Monitor your blood sugar levels if possible. Contact your doctor to discuss liver function testing to check for any damage. Future prevention includes reading all labels and informing restaurants about your dietary restrictions.
Yes, people who inherit only one mutated ALDOB gene copy are carriers. Carriers do not have symptoms and can process fructose normally. However, if two carriers have children together, each child has a 25 percent chance of inheriting both mutated genes and developing the condition.
Elevated ALT levels in blood tests suggest liver cell damage from fructose exposure. Your doctor will compare your results to normal ranges and track changes over time. Rising ALT levels may indicate you have consumed fructose accidentally or that your diet needs adjustment.