DEAR DR. GOTT: Do you have any information on fructose intolerance? I have been able to find only one book related to the problem. Thank you.
DEAR READER: Fructose intolerance, commonly known as hereditary fructose intolerance (HFI), is a genetic disorder in which the body is unable to break down fructose and some other sugars. It is known as an autosomal recessive disorder, which means that in order to be affected, each parent must have the mutation and pass it on to the child. If only one copy is passed on, the child will be a carrier but will not be affected.
This abnormal gene results in the body missing the enzyme fructose-1-phosphate aldolase, which is responsible for changing glycogen into glucose, which the body uses for energy. Without it, fructose-1-phosphate will build up in the small intestine, liver and kidneys. Following ingestion of fructose, sucrose and sorbitol (a sugar alcohol), the body’s blood-glucose levels will drop, causing hypoglycemia. Severe abdominal pain and vomiting may also occur.
Other symptoms include excessive sleepiness, jaundice, irritability, convulsions and more. Sufferers develop a distaste for sweet foods. Liver and kidney damage can occur, and may result in organ failure or death, so strict avoidance of all foods and drinks containing fructose and other sugars metabolized by fructose-1-phosphate aldolase is vital.
Fructose intolerance can sometimes be confused with fructose malabsorption, which is not life threatening but is more common. Fructose malabsorption can cause abdominal pain, bloating, gas and diarrhea but does not result in the liver or kidney damage. However, treatment for both conditions is the same.
The most important aspect of management is avoidance of all sources of fructose, sucrose and sorbitol, including fruits, fruit juices, table sugar, sodas, powdered sugar, sports drinks, honey, high-fructose corn syrup and a great deal more. This can be very difficult. Consulting a registered dietician and reading labels meticulously will be highly beneficial. The dietician can help you avoid fructose and maintain a balanced, healthful diet.
Boston University has an entire lab dedicated to the research of HFI and aldolase. It offers information about the condition, diagnosis, treatment, HFI-specific diets and research. There is also a support group, but it only accepts patients with medical-record confirmation of diagnosis. They say this is because while other support groups exist, many contain information for sufferers of fructose malabsorption, benign sugar intolerance and more that may not be applicable to HFI. If you are interested in joining the support group, you can apply online at www.bu.edu/aldolase/disclaim/disclaim.html. Others who are simply interested in learning more about HFI can visit www.bu.edu/aldolase/HFI/FAQ.html or www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001399.
