Ever thought that you were not doing the right thing by blending up a healthy fruit smoothie? Unfortunately, your stomach screamed in protest. The probable answer to this digestive distress, is fructose intolerance. Fructose, a naturally occurring sugar found in fruits and certain vegetables, can be a major pain point for those who can't tolerate it. A bunch of grapes or pancakes with honey can really wreck your day.
So, what exactly is fructose intolerance, and why does it seem to have a vendetta against our taste buds?
Fructose intolerance: A not-so-sweet surprise
Rahaf Mohammed Altowairqi, a Dubai-based clinical dietician, breaks it down: Fructose intolerance occurs when your body has trouble breaking down fructose, a type of sugar found in fruits, vegetables, and many processed foods. It might not be a life-threatening allergy, yet it can cause much discomfort, including bloating, gas, diarrhea, and other digestive problems. There are two kinds, hereditary and fructose malabsorption.
Hereditary fructose intolerance (HFI)
In hereditary fructose intolerance, undigested fructose builds up in the liver, kidneys, and intestines, causing symptoms like low blood sugar, jaundice, and seizures. In fructose malabsorption, undigested fructose travels to the large intestine, where it is fermented by bacteria, leading to gas, bloating, diarrhea, and abdominal pain....
This a genetic condition that prevents the body from properly metabolising fructose, a type of sugar found in fruits, honey, and many processed foods. As indicated by a 2023 study published in the American academic StatsPearl Journal, this condition is present from birth and can lead to severe symptoms if fructose is consumed. HFI is caused by mutations in the ALDOB gene, which provides instructions for producing the aldolase B enzyme. This enzyme is essential for breaking down fructose, as outlined in a 2022 study published in the World Journal of Clinical Pediatrics.
Without sufficient aldolase B, fructose can accumulate in the liver, kidneys, and small intestine, resulting in severe symptoms, when fructose is ingested.
HFI is a serious condition that can lead to severe symptoms. Individuals with HFI may experience frequent or prolonged vomiting, hypoglycemia (low blood sugar), and liver damage, including cirrhosis, if left untreated.
Fructose malabsorption
As Altowairqi explains, this is a more common condition where the absorption of fructose in the small intestine is impaired, leading to digestive issues.
In the case of fructose malabsorption, Helen Gerald, a Dubai-based clinical dietician, that fructose carriers, located within the enterocytes, which are intestinal cells, play a crucial role in transporting fructose. If there is a deficiency of these carriers, fructose may accumulate in the large intestine, leading to digestive problems.
Fructose malabsorption can occur due to various reasons, including gut dysbiosis, which is an imbalance of beneficial and harmful bacteria, excessive consumption of processed and refined foods, and underlying gut issues like irritable bowel syndrome. These factors can interfere with the proper absorption of fructose in the small intestine, leading to digestive problems.
In fact research has attempted to prove this: A 2018 study published in the BMC Gastroenterology Journal, an American academic journal, revealed that people with irritable bowel syndrome (IBS) often exhibit both fructose and fructan intolerance. Notably, those who were unable to tolerate one of these sugars were more likely to experience difficulties with the other as well.
The problems with the small intestine
A 2022 study published in the American Journal of Neurogastroenterology and Motility revealed that people with small intestinal bacterial overgrowth (SIBO) were more prone to fructose malabsorption compared to those without SIBO. Excessive bacterial growth in the small intestine can interfere with the proper absorption of fructose, leading to digestive symptoms.
As a result, with fructose malabsorption, the undigested fructose travels to the large intestine, where bacteria ferment it, leading to gas, bloating, vomiting, diarrhea, abdominal pain and chronic fatigue.
How can you treat fructose intolerance?
Well, there can be a few sweet solutions at hand. The most effective way to manage fructose intolerance is to adopt a low-fructose diet, explains Gerald. You might need to limit the consumption of high-fructose foods, beverages, certain fruits, vegetables, sweeteners and processed foods.
Here are some tips for following a low-fructose diet, explain both the experts:
Choose low-fructose alternatives: Prioritise berries over apples or pears, and utilize glucose or dextrose as alternative sweeteners to fructose-containing compounds.
Read food labels carefully: Look for added sugars, including high-fructose corn syrup.
Be mindful of hidden sources: Fructose can be found in unexpected places, such as salad dressings, sauces, and even some medications.
If your symptoms improve, you may be able to gradually reintroduce small amounts of fructose under the guidance of a healthcare professional. This can help you determine your tolerance level and identify any trigger foods.
The foods that you do need to avoid:
If you have fructose intolerance, it's important to be mindful of the foods you consume. Here's a list of foods that are typically high in fructose and should be avoided or limited:
• Fruits: Apples, pears, cherries, mangoes, watermelons and grapes
• Dried fruits: Raisins, apricots, prunes, and other dried fruits.
• Fruit juices: Apple juice, grape juice, and other fruit juices often contain high levels of fructose.
• Vegetables: Artichokes, asparagus, sugar snap peas, broccoli, sweet corn, beets.
• Sweeteners: Candies and honey
• Sweets and desserts: Candies, cakes, cookies, and pastries often contain high-fructose corn syrup or other high-fructose sweeteners.
• Snack foods: Many granola bars, cereal bars, and other snack foods contain added fructose.
• Sauces and condiments: Ketchup, barbecue sauce, salad dressings.
• Baked goods:Many commercially prepared breads, muffins, and other baked goods have high-fructose ingredients.
Why you should watch your fructose intake in general
Fructose intolerance isn't the only reason to watch your sugar intake. Even if you don't have this condition, excessive consumption of sugary drinks can still wreak havoc on your health. As Gerald says, “While it might seem harmless in fruits and vegetables, it can create problems, when you consume too much, especially in processed foods.”
Fructose can have an adverse impact on your blood lipid profile. The excessive fructose consumption may elevate VLDL cholesterol or ‘bad cholestrol’ levels, which can contribute to fat buildup around organs and increase the risk of heart disease, explain the experts. “When people consume a diet high in calories and fructose, their livers can become overwhelmed. This can lead to the liver converting excess fructose into fat, contributing to weight gain and other health issues,” adds Gerald. It could also increase the blood levels of uric acid, leading to gout and high blood pressure, and cause a deposition of fat in the liver, and leading to possible fatty liver diseases.
As experts summarise, while fructose intolerance is a separate condition, it's important to be mindful of your overall fructose intake for optimal health. If you suspect you have fructose intolerance, consult with a healthcare professional for a proper diagnosis and treatment plan.
