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Hereditary fructose intolerance

  • Definition

    Hereditary fructose intolerance is a disorder in which a person lacks the protein needed to break down fructose. Fructose is a fruit sugar that naturally occurs in the body. Man-made fructose is used as a sweetener in many foods, including baby food and drinks.


    Alternative Names

    Fructosemia; Fructose intolerance; Fructose aldolase B-deficiency; Fructose 1, 6 bisphosphate aldolase deficiency


    Causes, incidence, and risk factors

    This condition occurs when the body is missing an enzyme called aldolase B. This substance is needed to break down fructose.

    If a person without this substance eats fructose and sucrose (cane or beet sugar, table sugar), complicated chemical changes occur in the body. The body cannot change its energy storage material, glycogen, into glucose. As a result, the blood sugar falls and dangerous substances build up in the liver.

    Hereditary fructose intolerance is inherited, which means it is passed down through families. If both parents carry an abnormal gene, each of their children has a 25% chance of being affected. The condition may be as common as 1 in 20,000 people in some European countries.