Hereditary Fructose Intolerance (HFI)

By Marisa Ramiccio. May 7th 2016

Eating too much sugar can lead to a whole host of problems, but for some, the slightest taste of sugar can cause serious side effects and possibly even death. Those who suffer from this problem have a condition known as Hereditary Fructose Intolerance, which prohibits the body from digesting sugar.

This condition affects about 1 in 20,000 people, mostly in the western hemisphere and can only be inherited if both parents carry the mutated gene for it.


Fructose is a simple sugar that is naturally found in fruits. Most people don’t have a problem digesting it, but those with HFI can have a severe reaction if they eat fruit or foods that contain fruit juice or fructose. Some of the symptoms they may experience include:

  • Abdominal pain
  • Bloating
  • Diarrhea
  • Vomiting
  • Nausea
  • Low blood sugar
  • Liver dysfunction

Many of these symptoms will be displayed during infancy, so the intolerance can be diagnosed and treated at an early age. However, infants who have this intolerance may fail grow and gain weight at the expected rate.


As the name states, HFI is a hereditary disorder caused by a genetic mutation. Normally, fructose is metabolized in the liver by an enzyme known as adolase B and then is broken down into substances that produce phosphates.

But in those with HFI, the ALDOB gene, which is responsible for making the adolase B enzyme, is faulty. Because of this, fructose cannot be broken down and ends up accumulating in the liver, which leads to liver damage and dysfunction. Over time, the liver cells will actually die and this, mixed with a lack of phosphates, can lead to hypoglycemia, or low blood sugar.


Aside from liver dysfunction and hypoglycemia, prolonged exposure to fructose can also lead to other serious side effects such as jaundice, cirrhosis of the liver, seizures, a coma, kidney failure and even death. Because of the severity of these symptoms, it’s important to get diagnosed as early as possible.

If you’ve noticed any of the mentioned symptoms or suspect that you may have a problem digesting fructose, you may want to consult with your doctor. He or she can prescribe one of the following tests that will determine whether or not you have HFI:

  • Fructose intolerance test – For this test, the doctor will inject a small amount of fructose into the bloodstream and, under tightly controlled conditions, will monitor your blood sugar and phosphate levels.
  • Liver biopsy – A liver tissue sample is collected and studied to determine the presence and activity of adolase in the liver.
  • DNA test – This method involves scrutinizing your DNA from the genetic mutation that causes HFI. However, this test is not diagnostic, which means that a negative result does not necessarily mean you don’t have HFI.

These tests are the tests that are most often used and tend to be the most reliable. However, a doctor may also perform one of the following tests to diagnose HFI:

  • A blood clot test
  • A kidney function test
  • A liver function test
  • A urinalysis

Testing for HFI can be risky, particularly for newborns, but it can provide a clearer indication of whether or not you have a problem digesting sugar. Although you may not have HFI, you may have a similar disorder known as fructose malabsorption.

Fructose malabsorption is caused by the cells of the intestines that cannot absorb fructose. The symptoms are less severe than HFI and include stomach pain, bloating and diarrhea. Approximately 40 percent of those in the western hemisphere have this condition.


The only real way to treat HFI is by eliminating fructose, sucrose and sorbitol from your diet. This can be quite challenging as many foods contain those sweeteners, but, fortunately, many people who have HFI tend to develop distaste for sweet foods. However, there are some foods that aren’t sweet that contain sugars, which must be avoided as well. Here are some of the foods that those with HFI must eliminate from their diet:

  • Ham
  • Bacon
  • Lunch meat
  • Sweet potatoes
  • Sugar-coated cereals
  • Ketchup
  • Barbeque sauce
  • Mayonnaise
  • Salad dressing
  • Jams and jellies
  • Bread
  • Vegetables such as carrots, broccoli and tomatoes
  • Fruits
  • Fruit juices
  • Desserts

Although the remaining food choices may seem scarce, there are plenty of foods that those with HFI can eat, including:

  • Beef
  • Pork
  • Fish
  • Chicken Cheese
  • Saltines and soda crackers
  • Vegetables such as lettuce, spinach and celery
  • Rice
  • Spaghetti
  • Butter
  • Beans
  • Oil
  • Broth
  • Vegetable juices that don’t contain tomatoes

After changing their diet, those with HFI should begin to see a noticeable difference in how they feel. How well the diet works does depend on how the aldolase B enzyme functions in their body and whether their condition is mild or severe. But overall, people who have HFI can lead normal, healthy lives as long as they seek diagnosis and receive treatment early on.


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