Fructose malabsorption, formerly called dietary fructose intolerance, occurs when cells on the surface of the intestines aren’t able to break down fructose efficiently.
Fructose is a simple sugar, known as a monosaccharide, that comes mostly from fruit and some vegetables. It’s also found in honey, agave nectar, and many processed foods that contain added sugars.
The consumption of fructose from high fructose corn syrup has increased over 1,000 percent just from 1970–1990. It’s possible that this rise in consumption has led to an increase in fructose malabsorption and intolerance.
If you consume fructose and feel digestion issues, you may be affected by fructose malabsorption.
Fructans are fermentable carbohydrates that are composed of short chains of fructose with a single attached glucose unit. Fructan intolerance may coexist with fructose malabsorption or be the underlying cause of symptoms.
Hereditary fructose intolerance
A more serious issue and completely unrelated condition is hereditary fructose intolerance (HFI). This is a rare genetic condition that affects 1 in 20,000 to 30,000 people and occurs because the body doesn’t make the enzyme needed to break down fructose. This can lead to serious health issues such as liver failure if a strict fructose-free diet isn’t followed. The condition is most often detected when a baby starts consuming baby food or formula.
Fructose malabsorption is fairly common, affecting up to 1 in 3 people. Fructose carriers found in the enterocytes (cells in your intestines) are responsible for ensuring fructose is being directed to where it needs to go. If you have a deficiency of carriers, fructose can build up in your large intestine and cause gut issues.
Fructose malabsorption can be due to many causes that include:
- imbalance of good and bad bacteria in the gut
- high intake of refined and processed foods
- preexisting gut issues such as irritable bowel syndrome (IBS)
Symptoms for fructose malabsorption include:
- abdominal pain
- chronic fatigue
- malabsorption of certain nutrients, such as iron
In addition, there’s evidence that links fructose malabsorption with mood disorders and depression. One study showed that fructose malabsorption was associated with lower levels of tryptophan, which plays a big role in the development of depressive disorders.
However, whether one causes the other is unclear. In a study that involved 209 patients with IBS, about one-third had fructose intolerance. Those who were compliant with restricting fructose saw improvement in symptoms. If you’re living with Crohn’s, this nutrition guide may also help.
In addition, if you’re on a gluten-free diet but still having symptoms, you may be having trouble with fructose. It’s never a bad idea to get checked for fructose malabsorption if you have a major gut issue.
A hydrogen breath test is a common test used to diagnose issues with digesting fructose. It’s a simple test that doesn’t involve a blood draw. You’re required to limit carbohydrates the night before and fast the morning of the test.
At your doctor’s office, you’re given a high fructose solution to drink, and then every 20 to 30 minutes for several hours your breath is analyzed. The whole test lasts about three hours. When fructose is unabsorbed, it produces higher amounts of hydrogen in the intestines. This test measures how much hydrogen is on your breath from this malabsorption.
Eliminating fructose from your diet is another way to tell if you have fructose malabsorption. With the help of a registered dietitian, you can develop a plan to effectively remove any foods containing fructose and see if your symptoms resolve.
Different people have different tolerances for fructose. Some may be more severe than others. Keeping a food journal can help to track the foods you’ve eaten and any symptoms you have.
Managing an issue with the breakdown of fructose typically includes elimination of the sugar. Eliminating foods that contain high levels of fructose is a good place to start. These include:
- certain cereal bars
- certain fruits, such as prunes, pears, cherries, peaches, apples, plums, and watermelon
- apple juice and apple cider
- pear juice
- sugar snap peas
- desserts such as ice cream, candy, and cookies containing fructose sweeteners
When reading labels, there are many ingredients to look out for when trying to manage fructose malabsorption. Be mindful of the following:
- high fructose corn syrup
- agave nectar
- crystalline fructose
- fructooligosaccharides (FOS)
- corn syrup solids
- sugar alcohols
A FODMAP diet may also be helpful when trying to manage fructose digestion issues. FODMAP stands for fermentable oligo-, di-, monosaccharides and polyols. FODMAPs include fructose, fructans, galactans, lactose, and polyols. In some cases, those with fructose malabsorption may also not tolerate fructans found in wheat, artichokes, asparagus, and onions.
The low-FODMAP diet includes foods that are typically easier to digest for most people, and this can relieve common symptoms. Foods that have a 1:1 ratio of glucose to fructose may be tolerated better on the low-FODMAP diet than those foods that contain more fructose than glucose. This detailed guide includes what to eat while following a low-FODMAP diet.
Fructose malabsorption: Q&A
Are there any medical treatments available for fructose malabsorption?
While fructose malabsorption may improve with a reduced fructose diet, this condition may also suggest that small intestinal bacterial overgrowth (SIBO) is at play. In either case, antibiotics, probiotics, digestive enzymes like xylose isomerase, and a modified diet may be recommended.Natalie Butler, RD, LDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
Gut issues with fructose malabsorption vary from person to person, and so will the treatment.
Whether you have a mild or severe case, a fructose elimination diet or a low-FODMAP diet may be helpful. Following one of these diets for four to six weeks, and then slowly reintroducing different fructose foods and assessing tolerance, is a good way to start. Tailoring the diet based on your specific symptoms from foods will be best.
Work with a dietitian who can help support you along the way and develop a plan with you.