Fructose
Malabsorption
FAQ
Frequently asked questions
about a shitty medical condition
Illustration adapted from Amanda Oleander
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What is fructose?
Fructose is a naturally occurring simple sugar. You can find it in fruit, hence the name fructose, vegetables, or honey. Fructose also makes up 50% of table sugar, sucrose, the other half being another simple sugar, glucose.
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What is fructose malabsorption?
FM occurs when your small intestine cannot effectively absorb fructose, preventing it from reaching its destination, the liver. This leads to excess fructose in the gut, where it binds water and undergoes fermentation by gut microbiota, disrupting the normal digestive process.
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What are the symptoms?
Diarrhea or loose stools, gas, bloating, abdominal pain, chronic fatigue, headaches, sometimes nutritional deficiencies (tryptophan, folic acid, and zinc).
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How do I get tested?
With a hydrogen breath test. Procedure: Arrive on an empty stomach, brush teeth at the doctor's office, drink a fructose solution, breathe into a plastic bag every 15 minutes for 4 hours, and discuss results.
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What's the treatment?
As of 2020, there is no cure. However, FM can be managed by following a low- or no-fructose diet, and taking a xylose isomerase enzyme before a meal containing fructose. Brand names for xylose isomerase include Fructaid, Lutomerase, and others. Unless the FM is only a symptom of a broader gastrointestinal condition.
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What can I eat?
One of the best strategies, besides seeing a specialist, is to get a mobile app with a database of foods and their fructose content. For instance Food Intolerances or Monash University FODMAP Diet. A lesser-known option that is safe is to supplement with nutritionally complete powder food. For example Super Body Fuel (except for strawberry flavor). For other brands, be sure to check their list of ingredients.
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Anything else to avoid besides fructose?
Yes, the general advice is to limit or eliminate fructans and polyols. However, test the degree of your individual sensitivity. Fructans are chains of fructose molecules and are mainly found in garlic, onion, and wheat. Polyols are sugar alcohols and include sorbitol, mannitol, maltitol, xylitol, erythritol, isomalt.
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Can I eat sweet things?
Yes, but only those sweetened with glucose ie. dextrose, lactose, stevia, monk fruit extract, and artificial sweeteners except for polyols. Avoid foods sweetened with fructose, table sugar ie. sucrose, honey, high fructose corn syrup, which all contain fructose. This is not an exhaustive list, check your fructose diet mobile app for more.
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Do I need to go gluten-free?
No, unless you are a celiac or have a gluten sensitivity unrelated to fructose malabsorption. While the protein gluten itself is not an issue for fructose malabsorbers, wheat does contain fructans. Some gluten-containing grains, like oats, which contain gluten due to facility cross-contamination, are generally safe.
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What is a low FODMAP diet?
The acronym stands for Fermentable Oligo-, Di-, Mono-saccharides And Polyols, and the diet is recommended to IBS sufferers. Saccharide means carbohydrate and the prefixes refer to the number of sugar units – few, two, one – in one molecule of the saccharide. For fructose malabsorbers, the low FODMAP diet is overly restrictive as it advises against dairy products like yogurt, milk, and soft cheese due to the disaccharide lactose.
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Will my primary care physician be familiar with this disorder?
Unfortunately, the probability is on the lower side. While FM is still gaining recognition in the medical community, specialists such as gastroenterologists and registered dietitians are typically more familiar with diagnosing and managing this condition.
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Is it genetic?
There is anecdotal evidence fructose malabsorption runs in families, often undiagnosed. However, the origin of FM remains unresolved, and more research is needed to better understand its causes.
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Is fructose malabsorption fructose intolerance?
Fructose intolerance usually refers to Hereditary fructose intolerance, which is a separate condition from fructose malabsorption. HFI is caused by mutations in the gene that codes for the enzyme aldolase B. This enzyme metabolizes fructose in the liver rather than in the small intestine.
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Are there any online communities?
Yes, r/fructosemalabsorption on Reddit, Fructose Malabsorption USA and Fructose Malabsorption Victoria on Facebook. If you join, be a good person, but use critical thinking, and watch out for misinformation. Trust, but verify.
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About the Author
Inspired by the millionth fructose-induced diarrhea, Dave changed his major to molecular biology during graduate school. Now he is studying absorption and metabolism of fructose to identify the gene or genes that may be responsible for the development of fructose malabsorption.
