Fructose malabsorption – Diet, Test, Symptoms, Causes
Fructose is a term used for a monosaccharide or a solitary sugar and often called fruit sugar. It is like glucose but with a varied molecular content/structure. It may have the same calories as sugar but is a lot sweeter. The body can remain healthy and survive without fructose, thereby making it a non-essential nutrient.
The human body cannot absorb unlimited fructose. Most humans can consume 20-25 grams of fructose in a single meal. When a person is unable to intake even 25 grams of fructose in a meal, then he/she is said to be suffering from fructose malabsorption.
Fructose malabsorption is not the same as an allergic reaction. It does cause the usual allergic response symptoms like itchiness or hives.Unabsorbed fructose can result in diarrhea and bloating. Unabsorbed fructose takes in intestinal water and passes into the colon where bacteria react on it and break it down into small fatty acids chains and gases. This is what causes diarrhea and bloating.
Fructose naturally occurs in sugar beets, honey, certain veggies, sugarcane, wheat, and fruits. Foods and commercial drinks may also have fructose which may be naturally present or added as sweetener.
Symptoms of fructose malabsorption
Fructose malabsorption and ‘hereditary fructose intolerance’ are two dissimilar conditions. The latter is an uncommon genetic disorder wherein affected people lack the enzyme necessary for breaking down fructose. The condition is detected early in childhood and can cause severe health problems like liver and kidney damage. Contrarily, the former is a mild condition and may be diagnosed at any age.
The symptoms in either case may become evident in some hours post meals containing fructose, or after about 24 hours. Some patients may elicit the symptoms after consuming 20 grams of fructose, while some others may have a limit of just 1 gram.
Some of the common signs and symptoms of fructose malabsorption are listed below:
- Excessive flatulence, increased gurgling, abdominal pain, bloating, and diarrhea.
- Aversion to sweet-tasting foods in some patients.
- Fructose malabsorption related diarrhea can result in loss of essential nutrients like iron, vitamins, etc. from the body before their absorption by the intestines. This can ultimately result in anemia, nutrition deficits, and other medical problems.
- In rare cases, affected individuals may suffer from additional symptoms like anxiety, weight loss, headache, fatigue, depression, and sugar cravings.
Causes of fructose malabsorption
People of all age groups can suffer from fructose malabsorption. Some of its many causes are listed below:
- SIBO or increased presence of bacteria in the small intestine.
- Some people may inherit the condition from either parent with a GLUT-5 anomaly. GLUT-5 is a protein which transports fructose. In such cases, other members of the family are also susceptible to developing fructose malabsorption.
- Excessive intake of High Fructose Corn Syrup by babies, or increased amounts of fruit juice intake by children can cause fructose-malabsorption-linked toddler’s diarrhea.
- Damage of the intestinal walls due to varied therapies such as chemotherapy or radiation therapy can also cause fructose malabsorption.
- Underlying presence of celiac disease or dumpling syndrome, a condition characterized by rapid emptying of the stomach, can increase the susceptibility to developing fructose malabsorption.
It is important for the glucose to fructose ratio to be adequate for preventing fructose malabsorption symptoms. This is because a single glucose molecule helps absorb 1 fructose molecule. Thus when the glucose to fructose ratio is equal, it improves the absorption of fructose into the body even in fructose malabsorption patients.
Tests for fructose malabsorption
The standard test for verifying the presence of fructose malabsorption is the ‘Hydrogen Breath Test’. It is a simple procedure which does not need any drawing of blood and which can carried out at a clinic.
Some patients may opt for a fructose elimination diet instead of the breath test. It is best to carry out the diet exercise in consultation with a doctor who is aware of fructose malabsorption so as to ensure that the diet is proper and that sufficient nutrition is sustained during the period of elimination.
If the diet is carried out properly and the person is suffering from fructose malabsorption, then the results will be good. It may however be noted that if the elimination does not give proper results, but fructose malabsorption needs to be verified, then the hydrogen breath test needs to be conducted.
Fructose malabsorption – Diet which works
Doctors are currently unaware of any cure for fructose malabsorption. Patients can however manage the symptoms by going for a diet that contains the least amounts of fructose, or by completely eliminating it from the diet along with fructans and sorbitol.
A fructose free diet may include:
- Fruits such as blueberries, blackberries, limes, lemons, rhubarb, raspberries, and strawberries
- Vegetables like black beans, cauliflower, cabbage, chickpeas, celery, cucumbers, haricot beans, green peppers, kidney beans, lentils, leafy greens, shallots, and mushrooms.
- Fats and dairy products like butter, ice cream, cheese, lard, milk, margarine, yogurt, and vegetable oils.
- All meats and meat items, including chicken, beef, eggs, pork, fish, and turkey.