Hereditary fructose intolerance

Hereditary fructose intolerance is an illness where the enzyme aldolase B, which breaks down the fructose in the liver, intestines and kidneys, does not function adequately, causing an accumulation of fructose-1-phosphate in the cells that should metabolize it. This accumulation becomes toxic, and eventually causes hepatomegaly, cirrhosis, renal failure, among other disorders.

Fructose is a sugar that is found in many foods; as such it is found in fruits and numerous vegetables, associated with glucose as a sucrose or common sugar (fructose + glucose) or it can be synthesized in the body from sorbitol (a commonly used sweetener), being the latter another source of fructose.

Artificial fructose is used as a sweetener in many foods, including foods and drinks for babies.

Fructose intolerance is a autosomal recessive disorder that is transmitted from parents to children, i.e., the two genes inherited from both mother and father and needed to synthesize the protein, are defective.

The disorder is considered a rare disease since it has a low incidence in the population. It affects a limited number of persons, 1 in 20,000.


The onset of the symptoms depends on ingesting fructose. The first symptoms will appear when the baby is fed fruits, vegetables and foods with sugar added. Severe symptoms appear after eating large amounts of fructose: nausea, vomiting, sweating, lethargy, acute liver alteration among others, with or without hypoglycemia.


Couples with a family history of fructose intolerance who wish to have a baby may consider genetic counseling.

Most of the damaging effects of the disease can be prevented by sticking to a fructose-free diet.

Once a diet has been established, most of the signs and symptoms of the disorder quickly disappear, except for hepatomegaly, which can persist for months or even years.

As there is a lack of consensus currently among specialists about nutrition, the following lists are those recommended in Spain by hospitals, societies and prestigious specialists:

  • Tratamiento nutricional de los errores innatos del metabolismo. M. Ruiz Pons, F. Sánchez-Valverde Visus J. Dalmau Serra, L. Gómez López. 2ª edición. Ed. DRUG FARMA 2007 con el soporte de SHS-España.
  • Aproximación al tratamiento nutricional de los errores innatos del metabolismo (I). M. Ruiz Pons, C. Santana Vega, R. Trujillo Armas, F. Sánchez-Valverde.
  • Guía metabólica hospital Sant Joan de Deu.

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