Fructose Intolerance Symptoms in Children

fructose intolerance symptoms in children

Lactose and gluten are two more commonly known intolerances that put foods into the dangerous category, but many people may not be aware that fructose intolerance is also a problem that can make sweet foods, including otherwise healthy options like fruit into a dangerous dining option.

Food holds within it the immense power to do great good as well as great harm to our bodies and our wellbeing. Some foods are easy to recognise as being friends or foe. Broccoli, for example, is universally recognised as superfood for virtually everyone; transfats on the other hand are unanimously recognised as a detractor to good health.

Beyond the foods that fall into black and white categories of “good” and “bad” though, are a spectrum of “grey” foods that may be fine for some people to eat, but very harmful to others due to allergies, intolerances, disease and more.

Because diagnosing fructose intolerance as early as possible is key to a good prognosis and minimising symptoms, it is crucial for parents, caregivers and pediatricians to be well versed in understanding fructose intolerance and its symptoms.

A Fructose Intolerance Crash Course

The first step in tackling fructose intolerance symptoms is developing a fuller understanding of the nuances of what fructose intolerance is. To begin that learning process, it is helpful to become familiar with a few key terms directly related to fructose intolerance.


Fructose is a simple sugar found in fruit as well as in honey. Additionally, manufacturers can make fructose by altering the glucose molecule in foods such as corn to create products like high fructose corn syrup (HFCS) to use to add an extreme sweet taste to foods.

Food Intolerance vs. Food Allergy

Though the terms are sometimes used interchangeably, food allergies and food intolerances refer to two different problems.

A food allergy indicates an immune response that occurs in response to exposure and/or ingestion of the particular food. Food allergies can be instantly life threatening if not treated right away.

On the other hand, a food intolerance refers to the body’s inability to properly digest a food due to a lack of the right enzymes. Symptoms are often related to gastrointestinal (GI) symptoms, though not always. Symptoms can occur immediately after eating the offending food or may not occur until many hours after ingestion. Unlike a food allergy in which mere exposure can set off a reaction, the offending food must actually be consumed to trigger a food intolerance response.


When the body experiences food malabsorption it is unable to correctly absorb the nutrients from a food(s). It can be caused by a variety of reasons including certain diseases, inflammation, intolerances, and genetic conditions. Continued problems with malabsorption can result in malnutrition.

Hereditary fructose intolerance (HFI) and fructose malabsorption

With the terminology in mind for reference, it is easier to take a closer look to understand what fructose intolerance is. There are actually two conditions which are sometimes referred to under the umbrella of fructose intolerance: hereditary fructose intolerance (HFI) and fructose malabsorption. The two conditions have similar symptoms, but are two different conditions.

*Note that both conditions are entirely separate from glucose intolerance, which is the umbrella term for metabolic conditions (including but not limited to Type I and Type II Diabetes) that render the body unable to process glucose.

Hereditary Fructose Intolerance

As the name indicates, HFI is a genetic condition in which the body does not make enough of the aldolase B enzyme. This enzyme is required to breakdown the fructose molecule and turn it into glucose for the body to use for energy needs. Without the presence of aldolase B, when fructose is consumed it builds up in the kidney, liver, and small intestine.

Because of their small, developing bodies, untreated HFI is particularly dangerous for children. It is estimated that roughly one in 20,000 people suffers from HFI. People with HFI cannot properly breakdown any amount of fructose.

Fructose Malabsorption

Fructose malabsorption, or normal fructose intolerance as it is sometimes called, is a more common condition in which people have a limited ability to absorb the fructose molecule in quantities over 25 grams at any given time. This difficulty breaking down fructose leads an intolerance.

The severity of fructose malabsorption can vary and its occurrence is significantly more common than HFI. As many as one in three people are believed to have difficulty absorbing fructose. The exact causes are unknown, but some experts believe the extreme presence of sugar in the common North American and Northern European diets has led to an increase in incidence. People who have problems with fructose malabsorption may be able to breakdown small amounts of fructose.

Checklist Guide: A Closer Look at Fructose Intolerance Symptoms in Children

HFI symptoms and fructose malabsorption symptoms are largely similar. Further testing can determine which condition may be behind the symptoms (see following section for more information on fructose intolerance testing). Severity will vary from child to child. If you suspect your child may be suffering from either condition, keep an eye out for the following symptoms.

  • Vomiting
  • Abdominal pain and/or cramping
  • Extreme sleepiness or lethargy
  • Kidney failure*
  • Liver failure*
  • Convulsions*
  • Jaundice*
  • Diarrhea
  • Aversion to foods possessing a sweet taste
  • Bloating
  • Mood changes, including depression

*indicates a symptom that is particular to HFI, not to fructose malabsorption

How to Get a Diagnosis for Your Child

If you have noticed some or all of these symptoms in your baby or child it is key to get a proper diagnosis for your child and begin treatment.

Hereditary Fructose Intolerance

Because of the genetic nature of HFI, providing your child’s doctor with a family medical history is a vital piece of the puzzle in getting a correct diagnosis. Other common tests used to diagnosis HFI include an enzyme assessment to test for the presence of aldolase B and a fructose intolerance test. Testing for aldolase B is a more invasive procedure as it requires a liver biopsy to ascertain results.

A fructose intolerance test is less invasive. For this test, doctors intravenously inject a patient with fructose and the monitor its levels in the body. DNA based tests are also beginning to enter the market, but are not yet as common. Some doctors may suggest a hydrogen breath test, but this test is not considered to be as accurate for HFI as it needs to be.

Fructose Malabsorption

Fructose malabsorption can be assessed through a hydrogen breath test. For this test, a patient consumes fructose on an empty stomach and then has his or her breath analyzed. If hydrogen is detected in the breath during the test, it indicates a problem with fructose malabsorption, with greater amounts of hydrogen indicating a greater degree of a problem. The presence of hydrogen indicates improper absorption.

An elimination diet in which fructose is removed from the diet can also indicate if fructose malabsorption is a problem, though this means of assessment does not provide the conclusive, scientific evidence the hydrogen breath test does.

Getting Help: Treating Fructose Intolerance Symptoms

Though there is currently no hereditary fructose intolerance cure nor is there a fructose malabsorption cure, it is possible to treat the condition through dietary restrictions. No medications are needed.

In the case of hereditary fructose intolerance, consuming any and all sources of fructose must be avoided. For people suffering from fructose malabsorption however, a small amount of fructose may be successfully tolerated, though that amount will vary from person to person. Take care to avoid the foods on the following list, as well as foods containing any of these items as ingredients.

Fructose intolerance foods to avoid:

-Agave syrup
-Some vegetables with higher fructose content such as sugar snap peas, asparagus, cabbage and eggplant
-White sugar (Sugar is made from part fructose and part glucose)
-Brown sugar
-Maple syrup blends
-Processed desserts and treats
-Coconut Sugar
-Foods containing high fructose corn syrup
-Foods containing sorbitol (though sorbitol is not fructose, the body can convert it to fructose)

Prognosis for Fructose Intolerance

Overall the prognosis for both HFI and fructose malabsorption is a good one. While the prognosis is good when HFI is properly treated, note that continuing to consume fructose can lead to severe problems in patients. Infants and children with untreated HFI can experience renal and/or kidney failure, which can result in death, making early diagnosis critical.

Thankfully, adherence to a diet free of fructose leads to a positive prognosis for patients who suffer from HFI as well as those with a fructose malabsorption problem. Strictly following a fructose free diet can lead to a total elimination of symptoms.

Multiple resources including books, websites, pediatricians, and nutrition and dietetics professionals can help parents come up with a diet plan that successfully meets the needs of their child’s HFI or fructose malabsorption condition and live a full, healthy, happy life.