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 two types, mainly and it can appear almost at any time, so it is important to know its symptoms to detect intolerance early.
In case there is someone clueless in the room, fructose does not only 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 tests for fructose intolerance look like and what the treatment is usually like.
What is fructose intolerance and types
When it comes to fructose, it is not okay to address this intolerance as a type of allergy. When talking about a food allergy, an adverse and uncontrolled reaction is expected from our body’s defenses that try to protect itself from that element that causes the allergy.
Allergies to fruits and vegetables exist and cause this reaction in some cases, but there is no allergy to fructose, but the correct thing is to refer to it as an intolerance.
Continuing with the topic of what is fructose intolerance, it is convenient to know the two types that there are so we can break down the subject and see which one we fit in:
- Hereditary fructose intolerance: we are facing a genetic defect where we lack the enzyme Aldolase B. This causes a malfunction when metabolizing fructose and, in turn, that results in the accumulation of intermediates of the metabolism of the fructose. 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.
- Due to malabsorption: prolonged diarrhea, fatigue, depression, headaches, mental confusion, irritability, etc. If diarrhea lasts for many days, it can cause other essential nutrients for the body not to 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 disturbances, dermatitis, muscle aches, 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 a simple 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 case of unclear results, 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 that is done when we are adults, since the genetic mutation option is only for young children and is done through the genetic study with blood and other tissues tests .
With respect to the hydrogen test, what you are trying to find out is a malabsorption of fructose. It is a non-invasive and risk-free test, but it tends to give false positives. The purpose is to detect (orally) the fructose that reaches the colon without being absorbed, that is why the level of hydrogen and methane in the breath is measured . Because when fructose reaches the large intestine, it is metabolized and produces hydrogen and methane gases that are expelled with the breath.
The test begins after a first fasting baseline measurement and then other measurements are made every 15 or 30 minutes. This test can take up to 150 minutes.
The other test to make the diagnosis is the blood glucose curve test. It is often a painful, expensive, and less specific test. 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 kind 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.
Mainly, a diet low in fodmaps is prescribed, that is, all those fermentable short-chain carbohydrates. A good dietician and nutritionist will be the right person to take our case and to tell us, with the tests in hand, which diet is the best for us, that is, which foods we will have prohibited and which we will be able to eat.
Remember that fructose appears in fruits, vegetables, legumes, nuts, in 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.
