Causes of Fructose Intolerance

People in the United States consume as much as 8.8 million tons of fructose a year. Fructose is a monosacharide, or a single sugar, found naturally in fruits such as apples, peaches and prunes. It is also in honey and some vegetables. Fructose can also be man-made and used to sweeten many foods that people consume every day. Some people are fructose intolerant, meaning they become ill after eating foods that contain fructose.

Hereditary Fructose Intolerance

• Hereditary fructose intolerance is a rare genetic disorder. People with this disorder do not have enough of the enzyme aldolase to metabolize fructose that enters their systems. Without the enzyme aldolase to complete the conversion of fructose into glucose, fructose 1- phosphate accumulates in the liver, kidneys, and intestines and causes severe hypoglycemia. Severe complications can develop and result in liver failure and death.

Dietary Fructose Intolerance

• According to researchers at the University of Iowa Hospitals, anyone can develop dietary fructose intolerance. Also called fructose malabsorption, dietary fructose intolerance can develop when a person consumes large amounts of fructose. Even though human beings do not have enzymes in their intestines that digest fructose, most people can usually tolerate as much as 25 grams of this fruit sugar. People often experience unpleasant symptoms when they consume more than 25 grams of fructose. An abnormally large amount of fructose often transports proteins or bacterial overgrowth in the small intestines and causes people to suffer unpleasant symptoms.

Symptoms

• Symptoms of hereditary fructose intolerance include abdominal pain, vomiting and hypoglycemia following the ingestion of fructose. Infants with this condition become jaundiced and develop enlarged livers and spleens. Some babies develop seizures, bleeding and gout. Prolonged fructose ingestion in infants with hereditary fructose intolerance can lead to renal failure and death. People with dietary fructose intolerance experience bloating, flatulence, gurgling, diarrhea and abdominal pain. These symptoms, however, are usually not fatal and they often subside after the excess amounts of fructose leave the system.

Treatment

• People who have hereditary fructose intolerance must completely eliminate fructose and sucrose from their diets. For these individuals, fructose consumption can be fatal. People with dietary fructose intolerance can avoid unpleasant symptoms by consuming a diet low in fructose containing foods. Fructose gives food a pleasant taste, but it is not a nutrient necessary for good health.