Although not a true allergy, intolerance to fructose can be a serious and debilitating condition. As the name suggests, this is an inherited intolerance. It shows up right away in infancy and it means that a baby cannot digest fructose, a common type of sugar. Someone with hereditary fructose intolerance lacks the right enzyme to break down the sugar. There are characteristic symptoms in infants with this intolerance, but they are easy to confuse with other conditions.
Fructose and Intolerance
Fructose is a common sugar, found naturally in fruits and some vegetables. It is one of three basic sugars that are found naturally in our foods. Most sweeteners, white sugar, raw sugar, honey and others are made mostly of sucrose, which includes one unit of fructose and one of glucose. In other words, fructose is just about everywhere. If a food has sugar in it, it likely contains fructose.
For someone with hereditary fructose intolerance, digesting this sugar is impossible. They lack the enzyme that is needed to break it down and digest it. We know that this condition is hereditary, but it isn’t common. Estimates are that about one in 20,000 to 30,000 people have it. If both parents have the gene for fructose intolerance, each of their children will have a 25 percent chance of having the condition.
Symptoms of Fructose Intolerance in Infants
This hereditary condition is present immediately in infants, but the symptoms may not appear until he or she starts eating formula or other kinds of food. The signs in an infant include vomiting, poor feeding, difficulty eating fruits or high-sugar foods, sleepiness, convulsions, jaundice and irritability. Because the condition is not very common and the symptoms overlap with others, it is easy to misdiagnose fructose intolerance as a food allergy or as gastroesophageal reflux.
Tests for Hereditary Fructose Intolerance
Unlike food allergies, there are definite tests that can conclusively confirm a child has this condition. Blood sugar tests, enzyme tests, genetic tests and tests of the function of the kidneys and liver can all help a doctor confirm if an infant has or does not have fructose intolerance. Evidence from physical examinations that may indicate testing is necessary includes jaundice and an enlarged liver.
The Consequences of Leaving Fructose Intolerance Untreated
It can be tough to come to the right diagnosis with hereditary fructose intolerance. An infant can’t tell you how fruit makes him feel, and the symptoms of this condition look a lot like those of other more common problems, particularly food allergies. Making a diagnosis is crucial, though, because the complications from the condition can be very serious:
- Low blood sugar
- Liver failure
Treating Fructose Intolerance
Treating hereditary fructose intolerance is very much like treating a food allergy. Avoidance of fructose is the only way to treat it. The complications can be treated in other ways, but the only way to avoid getting sick or having complications is to keep fructose out of the diet. Naturally, this isn’t easy, but fructose and sucrose, which contains fructose, can be replaced with other sugars. These include maltose and glucose.
If you suspect your child has this condition, you need to see your pediatrician as soon as possible for testing. An early diagnosis gives a child the best possible chance of avoiding complications, some of which can cause lifelong health problems. For most children, this condition can be successfully controlled by avoiding fructose. In very rare cases a child may develop a severe form of liver disease that can’t be reversed even by removing fructose from the diet.
If you do find out your child has hereditary fructose intolerance, you can help him thrive by making sure he has the right diet. Avoiding fructose can be challenging, so ask your pediatrician for a referral to a dietician who can help you figure out what your child can and cannot eat. If you take the right steps and get the diagnosis early, your child can most likely go on to live a normal life, just with a special diet.