Do you know about Fructose Intolerance

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Registered: 03-19-2003
Do you know about Fructose Intolerance
Tue, 07-13-2010 - 1:14am
Fructose Intolerance

Hereditary Fructose Intolerance (HFI) is a rare genetic disorder of fructose metabolism due to a deficiency of the enzyme, aldolase B that finishes the conversion of partially converted fructose (fructose-1-phosphate) into glucose.
Fructose is the sugar found in fruit.


Hereditary Fructose Intolerance (HFI) should not be confused with Fructose Malabsorption. They are two different conditions but with some similar symptoms. In HFI fructose is not properly metabolised due to a deficiency of the enzyme, aldolase B. Normally, once fructose is absorbed it is transformed into fructose-1-phosphate by an enzyme called fructose-1-phosphate aldolase. Aldolase B in turn finishes the partially converted fructose to glucose (for energy). Lack of aldolase B results in the accumulation of fructose-1-phosphate in the liver, kidneys and intestine. This inhibits glycogen breakdown and glucose synthesis, thereby causing severe hypoglycaemia (low sugar levels) following ingestion of fructose.


Clinical symptoms include severe abdominal pain, vomiting, and hypoglycemia following ingestion of fructose or other sugars metabolized through fructose-1-phosphate. Prolonged fructose ingestion in infants leads ultimately to hepatic and/or renal failure and death. Patients develop a strong distaste for sweet food, and can avoid a recurrence of symptoms chronic course of the disease by remaining on a fructose free diet.

HFI may be relatively mild or a very severe disease. In the severe form, even eliminating fructose and sucrose from the diet may not prevent progressive liver disease.

Symptoms list:

  • Onset of symptoms after starting an infant on food or formula
  • Poor feeding as a baby
  • Irritability
  • Increased or prolonged neonatal jaundice
  • Vomiting
  • Convulsions
  • Excessive sleepiness
  • Intolerance for fruits
  • Avoidance of fruits and fructose/sucrose-containing foods
  • Doing well after eating foods without fructose/sucrose

The early symptoms of fructose intolerance may resemble those of galactosemia: irritability, jaundice, vomiting, convulsions and an enlarged liver and spleen. Later problems relate more to liver disease.


Fructose is the sugar found naturally in fruits. Man-made fructose is used as a sweetener in many foods, including baby food and drinks. The worldwide incidence rate of HFI remains unknown due to the difficulty of HFI diagnosis. The condition is widespread, however, most cases have been reported in Europe and North America. It may be as common as 1 in 20,000.

Signs & Tests

Physical examination may also show:

  • Jaundice (yellow skin) or icterus (yellow eyes)
  • Hepatosplenomegaly (enlarged liver and spleen)

Enzyme studies and Liver function Tests are the main tests that confirm the diagnosis. Others include:

  • Positive urine test for reducing substances
  • Hypoglycemia (low blood sugar), especially after receiving fructose/sucrose
  • Excess uric acid in blood (hyperuricemia)
  • Failure of the kidney to work properly with abnormally high amounts of sugars, amino acids and salts appearing in urine
  • Bleeding tendency revealed by coagulation tests of blood
  • Liver biopsy

Genetic testing for fructose intolerance may be available.


Complete elimination of fructose and sucrose from the diet is an effective treatment for most patients. Treatment of individual complications follows mainstream medical guidelines. For example, some patients can take medication to lower the level of uric acid in their blood and thereby decrease their risk for gout.


Absolute elimination of fructose and glucose produces good results in most children with fructose intolerance. A few children will go on to develop progressive liver disease. The prognosis depends on how soon the diagnosis is made and how soon fructose and sucrose can be eliminated from the baby's diet.


  • Hypoglycemia
  • Illness due to eating fructose- or sucrose-containing foods
  • Strong avoidance of fructose-containing foods due to noxious effects
  • Seizures
  • Bleeding
  • Gout
  • Liver failure
  • Death