Detecting fructose intolerance is a more or less long process that is carried out when the patient has symptoms of intolerance or allergy to foods with fructose. There are mainly two types and it can appear almost at any time, so it is important to know its symptoms to detect intolerance in time.
In case anyone in the room is clueless, fructose doesn't just come from fruit. Fructose is a type of monosaccharide sugar that appears in many fruits, but also in vegetables, legumes, nuts, eggs, some fish and some types of meat and, to make matters worse, it is an additive or sweetener that is used in many foods. already prepared.
And to make matters worse, common sugar, better known as sucrose, is a disaccharide. This means that it is made up of two elements, one of them is fructose and the other is glucose.
This is why you have to be aware of the symptoms of fructose intolerance to know how to detect it in time and remedy it. At the end of this text we will explain how the diagnosis is made, what the fructose intolerance tests are like and what the treatment usually is.
What is fructose intolerance and types
When it comes to fructose it is not right to address this intolerance as a type of allergy. When talking about food allergies, an adverse and uncontrolled reaction of our body's defenses that try to protect itself from that element that causes the allergy is expected.
Allergies to fruits and vegetables exist and cause this reaction in some cases, but there is no allergy to fructose, rather it is correct to refer to it as intolerance.
Continuing with the topic of what fructose intolerance is, it is convenient to know the two types that exist so we can go breaking down the topic and see which one we fit into:
- Hereditary fructose intolerance: we are facing a genetic defect where we lack the enzyme Aldolase B. This causes a malfunction when it comes to metabolizing fructose and, in turn, this results in the accumulation of intermediate products of fructose metabolism. In this case, it is irreversible and usually appears when the child begins to introduce fruit and vegetables into their daily diet.
- Malabsorption syndrome: It occurs when there is a basic problem and that is that the intestinal mucosa does not absorb fructose. That is where the problem begins, since it reaches the large intestine, it is fermented with the help of the intestinal microbiota and the symptoms of intolerance begin.
Main symptoms of fructose intolerance
As we have already come from the previous section, we know that there are two types of this intolerance, so now when classifying its symptoms, we are also going to make the same division.
- Hereditary condition: seizures, vomiting, jaundice, excessive sleepiness and irritability. These symptoms are sometimes related to liver disease, since there is also an accumulation of toxic substances.
- For malabsorption: prolonged diarrhea over time, fatigue, depression, headaches, mental confusion, irritability, etc. If diarrhea lasts for many days, it can cause other essential nutrients for the body to not be absorbed.
In addition to these symptoms, there are others that are also common in both types of fructose intolerance: abdominal discomfort, bloating, belching, flatulence, constipation, dizziness, nausea, menstrual disorders, dermatitis, muscle pain, weight loss, weakness in the nails, itchy skin, etc.
We must clarify that our symptoms may or may not coincide with those that we have mentioned.
Diagnosis, tests and treatment
Now the big question is, how is fructose intolerance diagnosed? It is not an easy job, but it is usually very effective and false positives are usually rare. There are different methods among which we highlight the hydrogen test, since it is the most widespread test because it is painless, non-invasive and quite reliable.
In the event that results are not enlightening, other medical tests can be performed to rule out other causes or diseases such as liver problems, irritable bowel syndrome, among others.
Diagnosis and main tests
The most widespread diagnostic test is the hydrogen test and it is the one done when we are adults, since the genetic mutation option is only for young children and is done through genetic study with blood and other tissue tests.
The hydrogen breath test aims to detect fructose malabsorption. It's a non-invasive and risk-free test, but it can produce false positives. The test detects (orally) fructose that reaches the colon unabsorbed, which is why it measures the levels of hydrogen and methane in the breath . When fructose reaches the large intestine, it's metabolized, producing hydrogen and methane gases that are expelled during respiration.
The test starts after a first fasting baseline measurement and then other measurements are taken every 15 to 30 minutes. This test can take up to 150 minutes.
The other test to make the diagnosis is the glycemia curve test. It is usually a painful, expensive test with less specific results. Finally, there is the intestinal biopsy, which consists of collecting a sample from the intestines to determine the functionality of the fructose transporters.
Treatments for fructose intolerance
Whether we have intolerance of one type or another, we already warn that there is no miraculous treatment, or anything that will cure it forever... It only remains to determine the strict diet that we must follow from now on.
A low-FODMAP diet is typically prescribed , meaning a diet low in short-chain fermentable carbohydrates. A qualified dietitian or nutritionist is the best person to manage your case and advise you, based on the evidence, on the most suitable diet—specifically, which foods to avoid and which to allow.
Remember that fructose appears in fruits, vegetables, legumes, nuts, eggs, soy flour, breads, cookies, wine, honey, fruit drinks and soft drinks, processed and ultra-processed with fructose among its ingredients, dressings and sauces with sucrose, garlic, onion, etc.