Fructose malabsorption

Fructose malabsorption, also known as “dietary fructose intolerance,” is a digestive disorder where the absorption of fructose is impaired by deficient fructose carriers in the cells of the small intestine. This results in an increased concentration of fructose in the entire intestine.

Carbohydrates are single sugars, or two sugars bound together, or thousands of sugars bound together called starch, or millions of sugars bound together called fiber. Fructose is a simple sugar. No carbohydrate can pass from your intestines into your bloodstream until it is broken down into a single sugar. For example, milk contains a double sugar called lactose that must be broken down into two single sugars before it can be absorbed into your bloodstream. Fifty percent of people on this earth get gas, cramping and diarrhea when they drink milk. To break the double sugar called lactose into the single sugars, your intestines must produce an enzyme called lactase. If your intestines do not produce lactase, you cannot split the double sugar into single sugars, and the double sugar cannot be absorbed in your upper intestines, so it passes to your colon, where bacteria ferment it to form gas, cramping and diarrhea.

Fructose is a single sugar that is absorbed much more slowly than another sugar called glucose. Most of the fructose in you intestines is converted to glucose and then absorbed into the bloodstream. The fructose that is absorbed goes directly to your liver where it is converted to glucose. Some people have intestines that do not convert fructose to glucose rapidly. Therefore, the fructose is not absorbed in the upper intestinal tract and it passes to the colon where bacteria ferment it to form gas, cramping and diarrhea.

This condition is found in about 30-40% of the population of Central Europe, and around half of these have symptoms resembling Irritable Bowel Syndrome.

This condition is common in patients identified to be suffering symptoms of Irritable Bowel Syndrome, although occurrence in these patients is not higher than occurrence in the normal population. Patients with fructose malabsorption often fit the profile of those with Irritable Bowel Syndrome.

Hereditary Fructose Intolerance (HFI) is a potentially fatal condition in which the liver enzymes that break up fructose are deficient. HFI is not the same as fructose malabsorption. HFI is usually diagnosed in young children and is considered very serious because it can cause damage to the liver and kidneys.


Signs, symptoms & indicators of Fructose malabsorption

Symptoms - Bowel Movements  

Bowel movement changes

Symptoms - Gas-Int - General  

Meal-related bloating


General flatulence

Counter Indicators
Symptoms - Gas-Int - General  

Absence of meal-related bloating

Conditions that suggest Fructose malabsorption


Fructose malabsorption could instead be


IBS (Irritable Bowel Syndrome)

Young K. Choi, M.D., a gastroenterologist, at University of Iowa, reported at the 68th Annual Meeting of the American College of Gastroenterology that fructose may be the cause of most cases of irritable bowel syndrome. When a person complains of pain in the belly, intestinal gas, cramps, and usually alternating constipation and diarrhea, doctors are expected to do a major workup looking for cancer and infections. When the workup fails to reveal a cause, the patient is told that he has irritable bowel syndrome. This study shows that many cases of irritable bowel syndrome are caused by eating fructose.

This study suggests that 30-60 % of patients with irritable bowel syndrome have fructose intolerance and can be cured by avoiding foods made with fructose.

[SF Phillips.Irritable bowel syndrome: making sense of it all. Best Practice & Research in Clinical Gastroenterology, 1999, Vol 13, Iss 3, pp 489-503]

Recommendations for Fructose malabsorption



Strong or generally accepted link
Strongly counter-indicative
Highly recommended



The sugars and starches in food. Sugars are called simple carbohydrates and found in such foods as fruit and table sugar. Complex carbohydrates are composed of large numbers of sugar molecules joined together, and are found in grains, legumes, and vegetables like potatoes, squash, and corn.


Excessive discharge of contents of bowel.


Specific protein catalysts produced by the cells that are crucial in chemical reactions and in building up or synthesizing most compounds in the body. Each enzyme performs a specific function without itself being consumed. For example, the digestive enzyme amylase acts on carbohydrates in foods to break them down.


An enzyme that aids the body in converting lactose to glucose and galactose. It is also necessary for digestion of milk and milk products.


The part of the large intestine that extends to the rectum. The colon takes the contents of the small intestine, moving them to the rectum by contracting.


Microscopic germs. Some bacteria are "harmful" and can cause disease, while other "friendly" bacteria protect the body from harmful invading organisms.


A sugar that is the simplest form of carbohydrate. It is commonly referred to as blood sugar. The body breaks down carbohydrates in foods into glucose, which serves as the primary fuel for the muscles and the brain.

Irritable Bowel Syndrome

(IBS) A condition that causes upset intestines for a long period of time. It is very unpleasant to the sufferer but tends to be harmless and usually does not lead to more serious complaints. The symptoms vary from person to person and from day to day. In order to be diagnosed with IBS, a person must have at least three of the following symptoms: pain in the lower abdomen; bloating; constipation; diarrhea or alternating diarrhea and constipation; nausea; loss of appetite; tummy rumbling; flatulence; mucous in stools; indigestion; constant tiredness; frequent urination; low back pain; painful intercourse for women.


Difficult, incomplete, or infrequent evacuation of dry, hardened feces from the bowels.


Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.

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