Fructose Intolerance - Frequently Asked Questions

Sugar Sensitivity

Definition, Prevalence, Symptoms, Testing and Causes

Two Types of Fructose Intolerance:

Don't be confused: there are two types of sugar sensitivity - usually Fructose Intolerance.

  • The first: Fructose Malabsorption is very common (1 in 3 people)
  • The other is rare  - Hereditary Fructose Intolerance (HFI) - but can be serious if left undiagnosed
  • Both lead to malabsorption illnesses - and both are easily treated a fructose-free Diet.


Prevalence of Fructose Intolerance

Hereditary Fructose Intolerance (HFI) is quite rare (less than one in 10,000). It is inherited (genetic) so you have it for life.

A positive diagnosis requires a stool test (DNA test) from your doctor.

Fructose Malabsorption is very common. Up to one in three people or 33% has some level of sugar intolerance - most commonly to Fructose.

However around half of these people may show no symptoms at all - until later in life. Fructose is found in some fruits and vegetables, and thousands of processed foods like soft drinks and confectionery.

Most intolerance to sugars like lactose, fructose and sorbitol is undiagnosed, but can be responsible for unexplained stomach bloating, diarrhea and intestinal distress in millions.

These sugars are used extensively in manufactured foods due to their sweetening power and low cost.

Fructose is just one thing that could be causing your symptoms.

There are more than twenty FOOD TOXINS – and they act in concert to damage cells and provoke the immune system. Therefore we recommend trying a LOW TOXIN DIET (reducing all food toxins) – as this is more likely to address all your ailments. Check foodintol® LoTox Living


Definition and differences for the two types of Fructose Intolerance

Definition of Hereditary Fructose Intolerance

Hereditary Fructose Intolerance (HFI) is a rare genetic condition where the enzyme for breaking down Fructose is not produced. If you discover you have fructose intolerance - you need to rule out HFI by seeing your doctor for a DNA test. With HFI it is vital to observe a very strict Fructose-free diet. Otherwise there is risk of serious disease including liver failure.

Definition of Fructose Malabsorption

Fructose malabsorption on the other hand is much more common and affects about 30% of people. It especially affects young people who have many soft drinks per week including soda and mixers. With Fructose Malabsorption special cells (epithelial cells) on the surface of the intestine are not available to break down the fructose sugars.

Comments: Treatment of HFI is a very strict Fructose-free diet for life. Treatment for Fructose Malabsorption is a Fructose-free diet with some concessions. You find a threshold level where you can eat some Fructose without getting symptoms. 

Learn more with the Free ebook about Food Toxins

What are the symptoms of Fructose Intolerance?

Symptoms of both types of Fructose Intolerance:

  • Gastro-intestinal distress: flatulence, bloating, diarrhea
  • Tiredness, Chronic fatigue
  • Malabsorption issues: low iron (anaemia), osteoporosis or other nutrient deficiency
  • Sugar cravings
  • Poor skin, nails and hair
  • Irritable Bowel Syndrome
    • For Fructose Intolerance (the more common type) there is clinical evidence associating it with mood disturbances and depression.

Comments: The symptoms of both types of Fructose intolerance are very similar to Lactose Intolerance so they can be mistaken for one another. You cannot diagnose your food intolerance from symptoms alone.

Learn more with the Free ebook about Food Toxins


What Causes Fructose Intolerance?

Causes of Fructose Intolerance

Blame your parents! All food intolerance is genetic – so you got it from your parents and grandparents. A very small percentage of people have the mored serious form of Fructose Intolerance (less than 1 in 10,000 people.)

Most Fructose intolerance is the Malabsorption type. It may be somewhat self-imposed by our modern sugar-heavy diets. Humans have not yet evolved systems to cope with such high sugar consumption. Consider the high level of sugars like fructose we ingest: in soft drinks, confectionery, desserts, cookies and thousands of processed foods and pharmaceuticals.

How do you Test for Fructose Intolerance?

The hydrogen or H2 breath test is often used. However many doctors now regard this test as unreliable.

The doctor may also use stool analysis to check for HFI. If you find you are Fructose-sensitive it is vital to rule out HFI as there may be serious health issues.

However the simplest, most reliable and accurate test is the Journal Method . . . as used in foodintol® LoTox Living

Comments: A simple Journal identifies the culprits. It is important to keep a journal because reactions can be delayed up to 3 days.


How do you treat Fructose Intolerance?

A Fructose-free or low-sugar diet is the best treatment - and the best management - for life. This is easy if you know which foods contain fructose - but many processed foods contain added Fructose under aliases like 'corn syrup'. You should consult a nutritionist.

When will I be cured from Fructose Intolerance?

The rare HFI (Hereditary Fructose Intolerance) cannot be cured. For this a strict Fructose-free Diet must be maintained in the long term.

The much more common Fructose Malabsorption cannot be cured either. But it is much easier to manage. Using a journal and monitoring yourself, you will find a threshold level that is easy to live with. That is - you will be able to eat some Fructose without suffering symptoms.

Comments: It is important to keep a journal of food eaten and symptoms on a daily basis, until you come to know your body's limits. A Journal lets you discover your threshold of intolerance - so you can eat some sweet foods without suffering symptoms.


How Sorbitol is linked to Fructose Intolerance

How Sugars Break Down in Malabsorption

Sorbitol breaks down into fructose and another sugar. So therefore it is a hidden source of Fructose in your diet.

Sugar malabsorption is the inability (in some people) of the small intestine to break down sugars like fructose (most common), lactose or sorbitol into smaller molecular fragments for digestion.

So the sugars progress down to the colon (large intestine) where bacteria break it down into short chain fatty acids and the gases carbon dioxide and hydrogen. These gases create enormous pressure in the intestine causing bloating, pain, diarrhea and flatulence.

In these people, because fructose (or lactose or sorbitol) is not absorbed by the intestine the condition is known as malabsorption, or an inability to be absorbed. But the molecule gets up to other mischief: it arrives in the colon where it drives an "osmotic purge". This means it attracts fluids back into the colon, making bowel motions loose and watery.

The main danger is that any other nutrients present can be lost from the body, like calcium and iron. Fructose malabsorption therefore is not only associated with gastro-intestinal distress but also the inability to absorb all kinds of nutrients which can lead to serious diseases like anaemia and osteoporosis.

Fructose malabsorption is notoriously undiagnosed and misdiagnosed. Recent findings are that Fructose malabsorption is associated with the early stages of depression and mood disturbances.


I think I might have food intolerance: What should I do?

Undiagnosed food intolerance can cause serious long-term health problems like osteoporosis, anaemia and many others. Learn more with the Free ebook about Food Toxins




All foodintol® information is based on research from peer-reviewed medical journals