A fructose allergy is a disorder that some people have that is caused by not having the protein necessary to break down this type of sugar.
Including fruit in your daily diet is recommended by doctors in order to maintain your health and feel happy. However, some people lack the enzyme called aldolase B, a substance that is essential to break down fructose (found in fruits and vegetables) and sucrose (found in sugar cane, beets or sugar).
According to the MedlinePlus webpage, this condition is hereditary. The body of a person who is allergic to fructose cannot transform sugar into glucose, lowering the sugar in the blood and making toxic substances accumulate in the liver.
Some symptoms that occur when the body does not tolerate fructose include diarrhea, abdominal pain and gas. As the Mayo Clinic webpage states, people who have this allergy should avoid foods that contain honey, palm or coconut sugar and molasses, among other foods.