Priya Bansal MD

Asthma and Allergy Wellness Center


2435 Dean Street, Unit C
 St. Charles, IL 60175-4827

Fructose Intolerance

Fructose intolerance exists when an individual does not manufacture the enzyme necessary to break down fructose during digestion. Fructose, in addition to occurring in nature, is used as a man-made sweetener in a variety of products, including many beverages and baby food. Fructose intolerance is a hereditary condition. Symptoms show up in young babies as soon as they begin drinking formula or eating. The condition is rare, but can be very serious, so it should be suspected when a baby has severe gastrointestinal issues, particularly if there is any family history of the disorder.

Symptoms of Fructose Intolerance

If a fructose-intolerant individual eats fructose (fruit sugar) or sucrose (cane or beet sugar), dangerous chemical changes can occur in the body. Because the body cannot change its glycogen, or stored energy, into glucose, the blood sugar falls precipitously, and toxins build up in the liver. Symptoms become evident soon after a baby begins drinking formula or eating food and range from mild to severe. Symptoms of fructose intolerance may include:

  • Excessive sleepiness
  • Poor appetite
  • Irritability
  • Jaundice
  • Vomiting
  • Convulsions

In general, babies with fructose intolerance become very fussy when being fed formula or baby food and may experience abdominal pain, diarrhea and gas.

Diagnosis of Fructose Intolerance

Upon palpation during a physical examination, the physician may detect liver or spleen enlargement. The child may also be jaundiced. Diagnostic tests will be ordered to confirm or refute the suspicion of fructose intolerance, including:

  • Blood tests for glucose and uric acid
  • Blood clotting tests
  • Enzyme studies
  • Genetic tests
  • Kidney and liver function tests
  • Urinalysis
  • Liver biopsy (in some cases)

If the patient does suffer from fructose intolerance, blood glucose will be low, especially after sugar is ingested, and uric acid levels will be high.

Treatment of Fructose Intolerance

For most patients, removing fructose and sucrose from the diet is an effective treatment. Depending upon how soon the disorder is diagnosed, other treatments may be necessary, such as lowering the blood level of uric acid to decrease the risk that the patient will develop gout.

Patients with fructose intolerance have to eat a diet low in fructose. In addition to avoiding sugars and its other forms, such as corn syrup, honey, maple syrup, molasses and agave syrup, they must avoid fructose found in fruit, fruit juices and other beverages, and some vegetables. Known offenders are:

  • Apples
  • Pears
  • Grapes
  • Watermelon
  • Asparagus
  • Snap Peas

Fructose intolerance ranges from mild to severe. Most children with this condition tolerate the majority of vegetables well and many are able to tolerate small quantities of fruits with lower quantities of fructose, such as bananas, blueberries, and strawberries. It is best for parents of children with fructose intolerance to work closely with nutritionists to find a comfortable, healthful diet.

Complications of Fructose Intolerance

While most instances of fructose intolerance are successfully brought under control with dietary changes, it is important to diagnose and treat the condition as early as possible. Untreated, fructose intolerance can lead to serious complications that may become life-threatening, such as hypoglycemia (low blood sugar), seizures, and liver failure.

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