Fructose Intolerance

What is fructose intolerance? Information on causes, symptoms, and foods that should be avoided by those who suffer from it.

Symptoms and Causes

Fructose intolerance is a condition that occurs when the body does not properly absorb this type of monosaccharide sugar, which is naturally present in many foods.

There are three types of fructose intolerance:

Primary fructose intolerance: The malabsorption is due to a failure in the Glut-5 transporter in the intestinal wall. In this case, fructose ferments in the colon and produces gases.
Secondary fructose intolerance: This is the most common type. It occurs due to poor absorption in the small intestine due to irritation of the cells or an imbalance in the microbiota.
Fructosemia: This is a rare hereditary fructose intolerance, typically seen in infants, and has no cure. A genetic alteration causes the liver to be unable to metabolize this sugar due to a lack of the enzyme aldolase B.

In recent years, many new cases of fructose intolerance have been diagnosed. However, it is still believed that there is underdiagnosis because the symptoms can be confused with other digestive disorders.

Symptoms

The most characteristic symptoms of fructose intolerance are:

Dyspepsia (pain, burning, or discomfort in the stomach)
Meteorism (excessive gas in the intestine)
Abdominal bloating (swelling)
Cramps and colic after meals
Nausea and vomiting
Diarrhea

Causes

The causes of fructose intolerance are metabolic and may include:

Malfunction of the specific fructose transporter (Glut-5)
Alteration in the function of the nonspecific transporter for glucose, galactose, and fructose (Glut-2)

It is important to note the difference between fructose intolerance and fructose allergy, which occurs when the body's immune system responds to this sugar as if it were a foreign agent trying to attack it.

Risk Factors

Anyone can develop fructose intolerance.

Complications

When fructose intolerance is not properly treated, it can lead to:

Hypoglycemia (low blood sugar levels)
Bleeding
Liver failure
Gout
Diabetes

Prevention

Fructose intolerance cannot be prevented, although adopting certain dietary habits reduces both symptoms and the risk of developing other conditions.

What doctor treats fructose intolerance?

Fructose intolerance is treated by specialists in endocrinology and nutrition, gastroenterology, or allergology, especially if there is an immune response to the sugars.

Diagnosis

breath test, which is based on the release of this gas when the intestine breaks down sugars. This test involves a baseline measurement, followed by periodic measurements (every 15 or 30 minutes over a period of one to two and a half hours) after ingesting a solution of fructose and sorbitol.

To ensure reliable results, the patient should attend the test in a fasting state and without having taken the following:

In the previous month: antibiotics. The patient should also not have undergone a colonoscopy or intestinal cleansing.
15 days prior: no taking of prokinetics or probiotics.
In the previous 24 hours: sugars, starches, carbonated drinks, chewing gum, tobacco. Physical exercise and tooth brushing should be avoided.

Treatment

There is no treatment that cures fructose intolerance. However, following a diet that eliminates foods that trigger it reduces symptoms and allows patients to live a normal life.

A low-fructose diet is recommended, so certain foods should be avoided, such as: