Understanding fructose intolerance and fructose malabsorption symptoms

Healthylife Pharmacy27 April 2018|3 min read

Unexplained bloating, gas and IBS symptoms may be due to fructose malabsorption, which is where the body is lacking the ability to break down fructose. Found in honey, fruit, fruit juice and some vegetables, fructose is a natural, simple sugar that, in some people, the intestines can’t break down efficiently. This leads to a build-up of fructose, resulting in uncomfortable gut symptoms.

Fructose malabsorption is diagnosed using a hydrogen breath test, which recognises unabsorbed fructose. Not every food that contains fructose is a problem if fructose malabsorption has been identified. It’s a matter of finding out what foods are suitable to eat as well as the quantity consumed.

About fructose

The foods we eat are made up of many different components, including sugars. Fructose is a simple sugar or monosaccharide and can be found in many different foods such as honey, agave nectar, wheat, fruit and vegetables. It is also found in high-fructose corn sugar in many processed foods and beverages.

High fructose foods include:

  • Apple
  • Applesauce
  • Dried fruits, e.g., raisins, dates
  • Fruit juice
  • Lychee
  • Pears
  • Watermelon
  • Stone fruits
  • Cherries
  • Mango
  • Nectarines
  • Peaches
  • Plums
  • Prunes

Fruits with a lower fructose content include bananas (unripe), avocado, berries, rockmelon, lemons, pineapple, kiwi fruit and grapes. When fructose is present as a chain of sugar units, it is referred to as a fructan and can cause many of the same digestive problems. Often, fructan intolerance and fructose malabsorption can coexist, or fructan intolerance can be the underlying cause of symptoms.

Foods that are high in fructans include:

  • Wheat products such as bread and pasta
  • Barley
  • Onions
  • Shallots
  • Garlic
  • Cabbage
  • Broccoli
  • Artichoke

Symptoms of fructose malabsorption

Fructose intolerance resembles symptoms of irritable bowel syndrome (IBS) and may include nausea, bloating, gas, abdominal pain and vomiting. Usually, there is diarrhoea, but this is not always the case and chronic constipation or sluggish bowels can also be a symptom. 

Fructose intolerance versus malabsorption

Fructose malabsorption occurs when the human intestine cannot absorb an unlimited amount of fructose. However, most people can absorb 25-50 g of fructose per sitting. By definition, the inability to absorb 25g of fructose per sitting is considered fructose malabsorption. This is estimated to occur in about one-third of the population.

Hereditary fructose intolerance occurs in a very small percentage of babies and is usually identified when formula or foods are commenced. 

Factors that may influence fructose malabsorption 

Research suggests that fructose malabsorption may be influenced by overall gastrointestinal health, including various gut disorders, if there’s a presence of small intestinal bacteria overgrowth (SIBO). The amount of fructose consumed as well as the amount of glucose, may also influence absorption.  

Diagnosis of fructose malabsorption 

Breath test

Your healthcare professional may perform a breath test, which measures levels of hydrogen. It involves breath analysis every 30 minutes for 3 hours after drinking a solution that is high in fructose. 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

Eliminating fructose from your diet is another way to tell if you have fructose malabsorption. With the help of a healthcare professional, you can develop a plan to effectively limit foods containing fructose and see if your symptoms improve. A temporary low FODMAP diet may be recommended to determine a reaction to other fermentable carbohydrates.

Determining your fructose tolerance

Once you have followed these diets for four to six weeks, you can start to reintroduce fructose-containing foods back into the diet to determine your threshold. This allows you to still enjoy foods you once ate but only in small amounts so that you are not experiencing any side effects. However, each case is individual, and some people experience mild symptoms and some very severe. In more severe cases, other underlying causes may exist, such as other food intolerances. It’s important to work with a healthcare professional so they can guide you through this process. 

Short and sweet

In short, fructose malabsorption is a common condition prevalent in the general population, particularly in those with IBS and SIBO. It may lead to uncomfortable digestive symptoms such as abdominal pain, bloating, nausea, vomiting and diarrhoea/constipation. The condition can be diagnosed via a breath test and managed by limiting fructose-containing foods. It’s important to discuss your individual needs with a healthcare professional.

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References

  1. https://www.healthdirect.gov.au/sugar 
  2. Helwig, U., Koch, A. K., Koppka, N., Holtmann, S., & Langhorst, J. (2019). The Predictive Value of the Hydrogen Breath Test in the Diagnosis of Fructose Malabsorption. Digestion, 99(2), 140–147. https://pubmed.ncbi.nlm.nih.gov/30179874/
  3. https://aci.health.nsw.gov.au/projects/diet-specifications/adult/allergy/fructose-low 
  4. Ebert, K., & Witt, H. (2016). Fructose malabsorption. Molecular and Cellular Pediatrics, 3(1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4755956/
  5. Melchior, C., Desprez, C., Houivet, E., Laura Armengol Debeir, Bril, L., Maccarone, M., Grout, E., Philippe Ducrotté, Guillaume Gourcerol, & Anne-Marie Leroi. (2020). Is abnormal 25 g fructose breath test a predictor of symptomatic response to a low fructose diet in irritable bowel syndrome? Clinical Nutrition, 39(4), 1155–1160. https://pubmed.ncbi.nlm.nih.gov/31113646/
  6. Hegde, V. S., & Sharman, T. (2020). Hereditary Fructose Intolerance. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK559102/
  7. Cuff, C., Lin, L. D., Mahurkar-Joshi, S., Jacobs, J. P., Lagishetty, V., Jaffe, N., Smith, J., Dong, T., Sohn, J., & Chang, L. (2023). Randomized controlled pilot study assessing fructose tolerance during fructose reintroduction in non-constipated irritable bowel syndrome patients successfully treated with a low FODMAP diet. Neurogastroenterology and Motility, 35(7), e14575. https://pubmed.ncbi.nlm.nih.gov/37052402/ 


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