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Fructose intolerance: Why does it happen and how to treat it?

Fructose intolerance can cause discomfort after eating certain foods. Here are the causes of the condition and how to prevent it.
Fructose intolerance
Fructose intolerance is when a person is unable to tolerate fructose which is a type of sugar in certain foods. Image courtesy: Adobe Stock
Shruti Bhattacharya Updated: 8 Jul 2024, 09:22 am IST
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Do you ever experience bloating or discomfort after eating fruits or sugary foods? It could be a sign of fructose intolerance. It happens when your body struggles to digest fructose, a type of sugar found in fruits, vegetables, and many processed foods. While it is not a severe allergy, fructose intolerance can lead to bloating, gas, diarrhoea, and other digestive issues and requires some dietary adjustments. Here is everything you need to know about fructose intolerance, its symptoms, and how to manage it for a happier gut.

What is fructose intolerance?

“Fructose intolerance occurs when the body struggles to either break down or absorb fructose, a type of sugar found in fruits, vegetables, and sweeteners. This unabsorbed fructose reaches the colon where gut bacteria ferment it, causing bloating, gas, and other digestive issues,” says nutritionist Abhilasha V.

Types of fructose intolerance

There are two main types of fructose intolerance:

1. Hereditary fructose intolerance (HFI)

This is a rare genetic disorder caused by a deficiency of the enzyme aldolase B, which is necessary for the metabolism of fructose, according to a 2023 study published in the StatsPearl Journal. This condition is present from birth and can cause severe symptoms if fructose is consumed.

Also Read: Glucose vs fructose: 6 differences that set the sugars apart

2. Fructose malabsorption

This is a more common condition where your small intestine is unable to absorb fructose. This can lead to symptoms like bloating, gas, and diarrhea when foods containing fructose are consumed, found in a 2016 study published in the Molecular and Cellular Pediatrics Journal.

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Causes of fructose intolerance

Fructose intolerance can be caused by different factors depending on whether it is hereditary or acquired.

1. Hereditary fructose intolerance (HFI)

Genetic mutation: HFI is caused by mutations in the ALDOB gene, which provides instructions for making the enzyme aldolase B. This enzyme is crucial for the proper metabolism of fructose, as found 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, which can trigger severe symptoms when fructose is ingested.

Colourful fresh fruits
Too much fructose in the system can lead to problems Image courtesy: Adobe Stock

2. Fructose malabsorption

1. Impaired fructose transport

“In fructose malabsorption, the cells lining the small intestine are unable to effectively transport fructose from the intestine into the bloodstream. This is often due to a deficiency or malfunction of GLUT5, a fructose transporter protein, explains the expert.

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2. Irritable bowel syndrome (IBS)

People with IBS often have issues with fructose absorption. A study published in the BMC Gastroenterology Journal found that people with irritable bowel syndrome (IBS) tested for both fructose and fructan intolerance. Interestingly, those who could not absorb one sugar (fructose or fructan) were more likely to have trouble absorbing the other one too.

3. Small intestinal bacterial overgrowth (SIBO)

An overgrowth of bacteria in the small intestine can interfere with fructose absorption. A study published in the Journal of Neurogasteroentrology Motility found that people with SIBO were more likely to have trouble absorbing fructose compared to healthy people.

4. Digestive problems

“Conditions like Crohn’s disease and ulcerative colitis can impair nutrient absorption, including fructose,” says the expert.

5. Dietary factors

A diet high in fructose or certain types of fibre can overwhelm the small intestine’s capacity to absorb fructose, leading to symptoms of malabsorption. However, more research is needed to prove this.

6. Infections

Gastrointestinal infections can temporarily damage the intestinal lining, affecting its ability to absorb nutrients, including fructose. However, more research is needed to prove the claim.

Symptoms of fructose intolerance

The symptoms of fructose intolerance can vary in severity depending on the amount of fructose consumed and the individual’s level of intolerance. Here are the common symptoms of fructose intolerance, as explained by the expert:

Gastrointestinal symptoms

  • Bloating
  • Gas
  • Diarrhoea
  • Abdominal pain or cramps
  • Nausea

Other symptoms:

  • Fatigue
  • Irritability
  • Headaches

How to treat fructose intolerance?

Treating fructose intolerance involves managing the condition through dietary changes and sometimes medical interventions. The goal is to reduce symptoms and maintain a balanced diet. Here are the primary approaches to treating fructose intolerance, as explained by the expert.

1. Eat a low-fructose diet

The most effective treatment is to adopt a low-fructose diet. This involves avoiding high-fructose foods and beverages, such as certain fruits, vegetables, sweeteners, and processed foods.

2. Find a substitute food

Replace high-fructose foods with low-fructose alternatives. For example, choose berries over apples or pears and use glucose or dextrose as sweeteners instead of fructose-containing ones.

3. Reintroduce fructose foods slowly

After symptoms improve, some people can gradually reintroduce small amounts of fructose to identify their tolerance level. This should be done under the guidance of a healthcare professional.

3. Medication

Over-the-counter enzyme supplements, such as xylose isomerase, can help some individuals break down fructose more effectively, reducing symptoms when consumed with meals.

4. Personalised nutrition plan

Consulting a registered dietitian can help create a balanced and nutritionally adequate diet that avoids fructose while ensuring all essential nutrients are consumed.

Which foods to avoid if you have fructose intolerance?

Managing fructose intolerance primarily involves avoiding foods that are high in fructose. Here is a list of foods to avoid or limit, as suggested by the expert.

1. Fruits: Apples, pears, cherries, mangoes, watermelons, and grapes.
2. Dried fruits: Raisins, apricots, prunes, and other dried fruits.
3. Fruit juices: Apple juice, grape juice, and other fruit juices are high in fructose.
3. Vegetables: Artichokes, asparagus, sugar snap peas, broccoli, sweet corn, and beets.
4. Sweeteners: Candies and honey.
5. Sweets and desserts: Candies, cakes, cookies, and pastries often contain high-fructose corn syrup or other high-fructose sweeteners.
6. Snack foods: Many granola bars, cereal bars, and other snack foods contain added fructose.
7. Sauces and condiments: Ketchup, barbecue sauce, salad dressings, and other condiments may contain high-fructose corn syrup.
8. Sodas and soft drinks: Often sweetened with high-fructose corn syrup.
9. Certain alcoholic beverages: Some wines and beers can contain high levels of fructose.
10. Sweetened teas and energy drinks: These may contain added fructose.
11. Sweetened cereals: Breakfast cereals often contain added sugars high in fructose.
12. Baked goods: Many commercially prepared breads, muffins, and other baked goods have high-fructose ingredients.

Brown bread
You can eat breads or other baked foods if you are intolerant to fructose. Image courtesy: Freepik

Foods to consume with caution

While some foods are high in fructose and should be avoided, others may be consumed in moderation, depending on individual tolerance levels:

  • Certain fruits: Berries (strawberries, blueberries), kiwi, bananas, and citrus fruits (oranges, lemon).
  • Certain vegetables: Leafy greens (Spinach, kale), cucumbers, bell peppers, zucchini carrots, and tomatoes may be tolerated in small quantities.
  • Sweeteners: Glucose and dextrose are better-tolerated alternatives to fructose.
  • Beverages: Water, herbal teas, unsweetened almond milk, and coconut water.

Things to keep in mind!

By avoiding high-fructose foods and choosing low-fructose alternatives, individuals with fructose intolerance can manage their symptoms effectively and maintain a balanced diet. However, it is crucial to consult with your healthcare provider before making any changes to your diet.

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About the Author

Shruti Bhattacharya is a content writer and editor for over 2 years. She specialises in writing on a variety of topics such as wellness, lifestyle, beauty, technology and fashion. Her current focus is on creating factually correct and informative stories for readers. ...Read More

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