Sorbitol is a sugar alcohol (polyol) commonly used as a sweetener in so-called sugar-free sweets and chewing gum, diet and diabetic foods. It is produced by the human body, occurs in fruit, beer and berries, is also contained in some medicines (e.g. mouth washes, cough syrups and laxatives) and cosmetics. Sorbitol has fewer calories and is less likely to cause dental caries than normal household table sugar, sucrose. Absorption in the small intestine occurs passively and is much slower than other sugars. This allows even moderate doses to reach the colon for fermentation, especially in individuals with a rapid intestinal transit.
A high proportion of healthy individuals develop abdominal bloating, gas, cramps and diarrhea at doses of 5 g and above.
Sorbitol and fructose intolerances often co-exist and mutually aggravate intestinal symptoms.
The concurrence of lactose and sorbitol is less clear, although there is some supporting evidence.
Frequency in population
35-70% of adults experience significant symptoms following ingestion of more than 10 g.
Intolerance appears more common in Asians and American blacks than in whites. Up to 70% of patients with Irritable Bowel Syndrome are sensitive to low doses of sorbitol.
These include bloating, abdominal cramps and pain, diarrhea, increased intestinal sounds and gas production, and nausea. These symptoms resemble those of functional bowel disease.
Little is known about long term effects of sorbitol intolerance, although severe weight loss has been reported. In diabetics high concentrations of sorbitol secondary to high blood glucose concentrations have been associated with nerve (small nerve fiber neuropathy) as well as eye damage.
Testing and diagnosis
The most reliable diagnostic test is the sorbitol breath test. Self-diagnosis of sorbitol intolerance is possible, once the foods and sweets with higher levels of sorbitol are known. A careful history should be taken in very case. Overlap with fructose intolerance often complicates the picture, in which case fructose breath testing is also recommended.
Breath tests are the most useful and non-invasive tests for determining the various sugar (e.g. fructose, lactose, sucrose) and sugar alcohol (e.g. sorbitol, xylitol) intolerances. They are well validated, widely used, but some discussion still exists about the ideal test conditions. These tests should not be used in infants and reduced doses of test compound are used in children. The tests procedures are identical for all the intolerances
The following are important details regarding the test procedure.
- Dietary restrictions, no smoking or excessive exercise from the day before testing and no antibiotics or colonoscopy in the last week pre-test.
- Ingestion of a specific amount of the sugar or sugar alcohol to be tested for intolerance.
- Regular breath samples taken for a standardized period.
- Diary of symptoms during the next day for calculation of the symptom index.
- Measurement of specific gases, e.g. hydrogen and methane, in the breath samples.
An intolerance is diagnosed based on the symptoms following the test and the gas concentrations in the breath samples. The diagnosis is confirmed by a significant decrease in symptoms whilst on a diet low in the poorly tolerated sugar or sugar alcohol. Expert dietary advice is very helpful for the identification of food and drink containing the difficult-to-spot offending ingredient.
No genetic tests are available.
Reduction of the intake of sorbitol to individually tolerated levels will rapidly lead to symptom relief in most individuals. Sorbitol is frequently encountered in diet, i.e. low calorie, foods and beverages, in high concentrations in sugar-free chewing gum and sweets / candies, in stone fruit (e.g. sweet cherries, plums) and dried and other fruit (e.g. apples, pears). Liquid medicines may contain sorbitol.
Fructose intolerance should be excluded by appropriate testing, due to the high degree of concurrence with and exacerbation of sorbitol intolerance (see Fructose intolerance).
Xylitol is another sugar alcohol that can produce similar symptoms as sorbitol. It is as sweet as sucrose, but with less calories, and has unique antibacterial activity evidenced by protection against dental plaque and caries, ear and upper respiratory infections, and may help control oral Candida infections. It exists naturally in many fruit, mushrooms, vegetables, oats, corn and birch trees. It is used extensively in sugar-free sweets / candies, as well as chewing gum.
Mannitol is a further sugar alcohol mainly found in mushrooms, pumpkin, seaweed, celery, candies and chewing gum. In sensitive individuals the symptoms will be the same as with sorbitol intolerance.