Hereditary Fructose Intolerance (HFI)

Dr. Yousef Elshrek

Hereditary Fructose Intolerance (HFI)

• What is HFI?

• HFI is a condition people are born with, usually

in families where there is no previous history.

The condition makes it difficult for the body ,

chiefly the liver and kidney to use fructose or

fructose – containing foods. The sugar is taken up

by the body, but in attempting to use sugar ,

toxic substances are produced , which lead to

serious illness

Fructose Intolerance

Fructose

Fructose-1-P

DHAP

+ Glyceraldehyde

ATP

ADP

Glycogen

Glucose-6-P

• Lack of Pi

• Allosteric Inhibition by F-1-P

F-1,6-BP

DHAP

G-3-P

Glucose

Pyruvate

1o Deficiency:

F-1-P

Aldolase Effects:

• F-1-P

• Pi

• Glycogenolysis

• Gluconeogenesis

• Blood Glucose

• Reducing sugar ( ) in urine

Treatment:

• Limit Fructose/Sucrose

• In another words :- HFI is an autosomal recessive disorder of fructose metabolism due to a deficiency of fructose-1-phosphate aldolase (EC 2.1.2.13) activity, which results in an accumulation of fructose-1-phosphate in the liver, kidney, and small intestine.

• The accumulated fructose-1-phosphate inhibits glycogen breakdown and glucose synthesis, thereby causing severe hypoglycaemia following ingestion of fructose (Fi. 1).

• Prolonged fructose ingestion in infants leads ultimately to hepatic and/or renal failure and death.

• Patients develop a strong distaste for sweet food, and can avoid a recurrence of symptoms chronic course of the disease by remaining on a fructose- and sucrose-free diet.

How is HFI diagnosed? • The only definitive way to ascertain if one

is suffering from HFI is to have one of two tests:

1. An enzymatic assay to determine aldolase activity.

– The aldolase is obtained from patient liver tissue in an invasive surgical procedure called a liver biopsy.

2. A fructose tolerance test. Fructose is injected intravenously under controlled conditions where acute glucose, fructose, and phosphate levels are monitored.

• HOWEVER, both tests represent

considerable risk, especially in a newborn.

• A newer, non-invasive DNA test is readily

becoming more available.

• While the DNA test is not diagnostic

because negative results do not guarantee

that one does not have HFI, positive

results, along with clinical symptoms, are

strong indicators of disease.

• A presumptive diagnosis can be made.

• An unreliable method is the H2 breath test. The hydrogen breath test is a safe and noninvasive procedure that may diagnose fructose malabsorption.

• Following ingestion of fructose, the hydrogen concentration of the patient’s breath is measured at various time intervals.

• An increase above baseline hydrogen concentration suggests fructose malabsorption.

• NOTE: This test has not been shown to be an effective means of diagnosing fructose intolerance.

HFI Treatment • The normal treatment, if you suffer from HFI, is a strict

fructose free diet.

• This involves exclusion of anything containing fructose, sucrose, or sorbitol.

• Implementation and adherence to this diet is often difficult, but not impossible.

• People on this diet live normal and healthy lives, although the danger of inadvertent fructose ingestion remain.

• Furthermore, it is unclear what long-term effects there might be on liver function from prolonged neonatal encounter with fructose. In extreme cases of life-threatening liver damage, liver transplants have been performed.

• These consequences are not likely if, instead of HFI, there is a fructose malabsorption problem.

• Treatment, however, of both is similar.

Foods to Avoid • Eliminating more than just fruit and honey is necessary when

following a low fructose diet because it is present in many processed foods.

• Read nutrition labels and ingredients lists carefully to determine what foods are safe and which ones you want to avoid.

• The words fructose, sucrose, sugar, high fructose corn syrup, honey, sorbitol or sweetened milk indicate the presence of fructose.

• Clinic, and may cause symptoms in your digestive tract when eaten.

• If you are unsure about an ingredient, contact the manufacturer and speak to a representative who can give you more information about it. Keeping a food diary will help you keep track of which foods cause a reaction so you can eliminate them.

• Fruit • Although you can safely consume fruit on a low

fructose diet, it is important to know which ones are high in fructose.

• High fructose fruits include watermelon, pineapple, oranges, apples, pears, peaches and mangoes.

• However, some people can tolerate eating some of these fruits in small amounts and in combination with other foods.

• Juices from concentrate should be limited because they contain much more fructose in a serving than fresh fruits do

• Sweeteners

• Sweet foods are likely to contain some form of fructose.

• High fructose corn syrup is one that you should limit or avoid if you are maintaining a low fructose diet.

• Soda, candy, packaged desserts, yogurt, jam, condiments and some sports drinks contain this sweetener.

• However, many manufacturers are creating products that don't use high fructose corn syrup, but be careful because they are likely to have some other sweetener in them.

• Any food sweetened with sorbitol, fruit juice or honey should also be limited.

• Aspartame is fructose-free, but health experts debate its safety so consume it in moderation.

What to Eat • There are plenty of foods you can eat on a low fructose

diet so that you are covering your nutrient needs and staying healthy.

• The University of Virgina Health System recommends meat, dairy, eggs, beans and vegetables.

• Combining these foods will create balanced meals that offer nutrition and protection from health problems.

• The Mayo Clinic advises contacting a dietitian for advice that is specific to your concerns and for a comprehensive list of foods you can and cannot eat on a low fructose diet.

• Meats • Fresh meats contain no fructose. They are also high in

protein and iron, and low in carbs. Red meat, pork and sausage are all high in fat as well. Chicken and turkey breasts are lean and contain no fructose.

• Fish • Catfish, flounder, tilapia, salmon, trout, herring, mackerel

and tuna are all types of fish that are low in fructose. They are also high in protein and low in carbs. Shellfish, such as crabs, lobster, shrimp, mussels and oysters are all low in fructose as well.

• Beans • Beans in their natural state are free of fructose. They are

also high in fiber, protein and complex carbohydrates. Broad beans, pinto beans, lima beans, lentils and black beans are examples. Once any of these beans become canned and any type of sugar is added, they are no longer low in fructose.

• Whole Grains • Whole grains have a high fiber content and low

fructose content. They are also high in complex carbs and have moderate amounts of protein. Oat bran, oatmeal, millet, Kamut, quinoa, barley and buckwheat are examples.

• Eggs • Eggs contain no fructose, are low in carbs and are

high in protein and fat. This includes the yolks and whites, and egg substitutes as well.

• Seeds and Nuts • Seeds and nuts are low in fructose, high in protein,

healthy fats and fiber, and low in carbs. However, any type of seeds or nuts that are honey roasted or covered with sugar are high in fructose

• Vegetables • The majority of vegetables are low in fructose.

Iceberg lettuce, green peppers, broccoli, Brussels sprouts, zucchini, radishes, cabbage, celery and mushrooms are examples.

• Dairy • Dairy products, such as cheese, milk and

buttermilk are low in fructose. These items are also high in calcium, protein and fat. Plain yogurt is low in fructose, but varieties that are flavored with fruit or high fructose corn syrup are not.