Which are the causes of Fructose Intolerance?

Fructose intolerance, also known as hereditary fructose intolerance (HFI), is a rare genetic disorder that affects the body's ability to metabolize fructose. It is caused by a deficiency of the enzyme aldolase B, which is responsible for breaking down fructose in the liver. Without this enzyme, fructose cannot be properly processed, leading to a range of symptoms and complications.

Genetic Mutation: The primary cause of fructose intolerance is a genetic mutation in the ALDOB gene, which provides instructions for making the aldolase B enzyme. This mutation is inherited in an autosomal recessive manner, meaning that both parents must carry a copy of the mutated gene for their child to develop the condition. If both parents are carriers, there is a 25% chance with each pregnancy that the child will inherit two copies of the mutated gene and develop fructose intolerance.

Lack of Aldolase B Enzyme: The genetic mutation in fructose intolerance results in a deficiency or complete absence of the aldolase B enzyme. This enzyme is crucial for breaking down fructose into usable forms of energy. Without it, fructose builds up in the liver, leading to a toxic accumulation of substances that can damage liver cells and interfere with normal liver function.

Fructose Overload: Fructose intolerance is triggered by the consumption of fructose-containing foods and beverages. When individuals with fructose intolerance consume fructose or sucrose (which is made up of fructose and glucose), the excess fructose cannot be properly metabolized, leading to a range of symptoms. The severity of symptoms can vary depending on the individual's tolerance level and the amount of fructose consumed.

Symptoms: The symptoms of fructose intolerance can range from mild to severe and typically occur shortly after consuming fructose or sucrose. Common symptoms include abdominal pain, bloating, diarrhea, nausea, vomiting, and low blood sugar levels. In severe cases, fructose intolerance can lead to liver and kidney damage, growth retardation, and even death if left untreated.

Diagnosis: Fructose intolerance is diagnosed through a combination of medical history, physical examination, and specialized tests. These tests may include a fructose tolerance test, genetic testing, and liver function tests. It is important to consult a healthcare professional for an accurate diagnosis and appropriate management of the condition.

Management: The primary treatment for fructose intolerance is a strict fructose-free diet. This involves avoiding foods and beverages that contain fructose, sucrose, and certain artificial sweeteners. It is essential to read food labels carefully and be aware of hidden sources of fructose. A registered dietitian can provide guidance on suitable dietary choices and help ensure proper nutrition.

In conclusion, fructose intolerance is a genetic disorder caused by a deficiency of the aldolase B enzyme, which is responsible for metabolizing fructose. The condition is inherited in an autosomal recessive manner and can lead to a range of symptoms and complications. Proper diagnosis and adherence to a fructose-free diet are crucial for managing fructose intolerance and preventing associated health problems.