Although most children have no trouble digesting fructose, a monosaccharide found in many foods, some kids lack the necessary enzyme to properly break fructose down and absorb it. This condition, generally called fructose intolerance, can produce various levels of symptoms, ranging from mild to life threatening. If your child is having tummy troubles, it is worth at least considering this condition as a possible cause.
What is Fructose Malabsorption?
Fructose, which is found in many fruits and some vegetables, and is also used as an added sweetener in many processed foods, is absorbed through a transporter (GLUT5) in the intestinal lining. Some people have a deficiency of this transporter and are unable to fully absorb fructose. When a person with a deficiency of GLUT5 ingests a diet high in fructose, excess fructose remains in the bowel, which is then rapidly devoured and fermented by the normal gut flora. This can lead to symptoms such as bloating and gas along with a laxative-like effect.
Other symptoms of fructose malabsorption may include:
- Nutrient deficiencies
- Mood changes
- Brain fog
The onset of fructose malabsorption can occur at any age and may be caused by a number of factors, including:
- Natural deficiency of the fructose transporter
- High intake of refined or processed foods
- Imbalance of good and bad gut bacteria
- Preexisting gut issues such as irritable bowel syndrome (IBS)
Fructose malabsorption is relatively common and estimated to be present in 1 in every 3 people.
Is There a Difference Between Fructose Malabsorption and Fructose Intolerance?
“Fructose intolerance” is a general term often used to cover two different conditions: one being fructose malabsorption and the other is a condition known as hereditary fructose intolerance (HFI). HFI is a rare genetic condition that is estimated to affect one in 20,000 to 30,000 people. People with HFI do not have any of the enzyme necessary for the breakdown of fructose. This condition can lead to serious health issues, including liver failure, if a person does not adhere to a strict fructose-free diet. This condition is often detected when a baby begins consuming formula or baby food.
Diagnosis of Fructose Malabsorption
The standard test to determine if a person has fructose malabsorption is called a fructose breath test (or hydrogen breath test). This simple test is non-invasive and can be done in a doctor’s office. This test is given to test the measure of the rise in hydrogen in a patient’s breath after an oral dose of fructose is administered. The fructose breath test can produce false positives, so it is best that it be carefully interpreted by a physician (as opposed to ordering a test online and reading the results at home).
Some patients do opt to do a fructose elimination diet in place of the test, but it is best done with the guidance of a health practitioner who is familiar with fructose malabsorption to ensure the diet is properly initiated and adequate nutrition is maintained during the period of elimination – especially in children. If clear results are not yielded after an elimination diet, a breath test should then be considered.
Treating Fructose Malabsorption
The treatment for fructose malabsorption is similar to that of HFI but may not be as strict. Most healthcare professionals recommend that patients with fructose malabsorption lower the amount of fructose in the diet. This includes the removal or limitation of foods including fruits (such as prunes, cherries, pears, peaches, plums, watermelon and apples), some vegetables (including sugar snap peas), sports drinks, some cereal bars, powdered sugar, soda, fruit juices and honey, and milk may also need to be removed from the diet.
Read labels carefully if your child has fructose malabsorption issues and watch out for any food items that list the following ingredients:
- Corn syrup solids
- High fructose corn syrup
- Agave nectar
- Crystalline fructose
- Sugar alcohols
- Fructooligosaccharides (FOS)
If your child can tolerate some fructose in her diet (and if your physician gives you the clearance to add in some low-fructose-containing foods), the following may be better tolerated:
- Apricots (raw)
- Brussel sprouts
- Green beans
- Lettuce (common)
If you suspect your child has a problem with digesting fructose, talk to your pediatrician about which food options are best for her.