All About Fructose Intolerance
Before we begin to explain fructose intolerance, it’s important to know how to distinguish it from an allergy. On the one hand, allergy is a reaction mediated by antibodies and triggered by proteins. On the other hand, intolerance is the body’s reaction to a lack of an enzyme that’s in charge of digesting sugars.
There are 2 forms: hereditary and malabsorption. The first affects 1 in every 20,000 and manifests after six months when introducing foods, due to the lack of the enzyme fructose-1-phosphate aldolase. In contrast, malabsorption affects 40 to 60% of the population and is usually secondary to some digestive pathology.
Likewise, you should know that malabsorption can be associated with intolerance to polyols that end in -ol, such as sorbitol, erythritol, and xylitol, among others, since they have a very similar structure.
In both cases, the diagnosis is made using the hydrogen breath test. It consists of quantifying the gas your body produces after ingesting 50 g of fructose over time.
Fructose and sorbitol: what they are and their sources
Fructose is the natural sugar in fruits, some vegetables, and honey. In addition, it’s usually used to sweeten other food products, such as cookies, pastries, chocolate, soft drinks, and other drinks, as well as those for people with diabetes. Along with glucose, it’s part of table sugar.
You can also find sorbitol in fruits, some vegetables and, along with the rest of polyols, in sugar-free products and chewing gum. Toothpaste, body creams, bath gels, and cosmetic products contain it as well.
Why does fructose intolerance occur?
At this point, it’s worth knowing that the absorption of fructose is dose-dependent. This is because the capacity of its transporters to cells is limited (from two to five grams). Thus, it’s the same one that sorbitol uses.
For this reason, since it can’t bind, it circulates freely to the intestine, where bacteria ferment it. As a consequence, gases and other digestive symptoms appear, causing discomfort.
However, the question is: why does it happen? An alteration in the permeability of the intestinal wall and the microbiota causes the vast majority of cases. Indirectly, stress, poor diet, and vitamin D deficiency, which plays a role in food tolerance, cause the alteration.
Symptoms of fructose intolerance
Mainly, the symptoms are digestive (nausea, vomiting, diarrhea, constipation, gas, bloating, and discomfort). Nevertheless, it can also cause fever, headache, tiredness, depression, menstrual irregularities, muscle pain, itchy skin, weight loss, and tongue sores and ulcers.
If it’s hereditary, the symptoms are dehydration, drowsiness, hypoglycemia, kidney and brain failure, and even liver dysfunction.
If you suffer from hereditary fructose intolerance, you must avoid fructose for life and take vitamin C supplements. On the other hand, if you have malabsorption, you must follow a very low-fructose diet (2-3 g/day). It’s essential for you to value your tolerance to restricted foods.
Likewise, you need to avoid fructans as well. This is a very long fructose chain that you can find in garlic, onion, artichokes, asparagus, and cruciferous vegetables (cabbage, cauliflower, broccoli, Brussels sprouts, etc.). In fact, even legumes, especially chickpeas and beans, can make you sick. However, you can try them skinless and crushed.
In short, it’s important that you go see a dietician or dietitian-nutritionist so they can recommend a diet to follow and evaluate your evolution. They can even help you reset your microbiota and resolve the intolerance if it’s momentary.It might interest you...
All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.
- Salas-Salvadó, J.; Bonada Sanjaume, A.; Trallero Casañas, R., Engràcia Saló Solà, M. y Brugos Peláez, R. (2014). Nutrición y dietética clínica. ElSevier.
- Pérez Aisa, A y Riquelme, A. (n.d.). Intolerancia a la fructosa-sorbitol. AEGASTRO(Asociación Española de Gastroenterologia). [Consultado 14 agosto 2019] Disponible en: https://www.aegastro.es/sites/default/files/archivos/documento-grupo/intolerancia_fructosa_-_sorbitol_0.pdf
- Guía Metabólica. (n.d.). Intolerancia Hereditaria a la Fructosa. [Consultado 14 de agosto de 2019] Disponible en: https://metabolicas.sjdhospitalbarcelona.org/ecm/intolerancia-hereditaria-fructosa-ihf