Sorbitol is a natural sugar-alcohol, or polyol, naturally found in some fruits but also used as a sweetener in sugar-free products, while lactose is mostly found in dairy products. These two short-chain sugars share the particularity of being malabsorbed in some people, resulting in gastrointestinal symptoms similar to IBS, or irritable bowel syndrome, such as diarrhea, constipation, flatulence, bloating, abdominal pain, discomfort and cramping.
Mechanism
If you are intolerant to sorbitol and lactose, these sugars will first attract a lot of water in your intestines, creating a abdominal distension and osmotic diarrhea. Later, when these sugars reaches your colon, they will be fermented by the bacteria in your intestines, producing gases, which will create even more abdominal distension, pain, flatulence, discomfort and cramping.
Diagnosis
Both lactose intolerance and sorbitol malabsorption can be diagnosed with a hydrogen breath test. These tests have to be performed on separate days and require you to follow a low-residue diet, according to the lab's instructions the day prior to the test. A predetermined dose of sorbitol or lactose will be given to you and the amount of hydrogen present in your breath over the next two to three hours will be analysed and measured. High levels of hydrogen to one of these tests indicate that the sugar is not well absorbed and is fermented by bacteria in your gastrointestinal tract.
Lactose
Lactose in the natural sugar found in milk and other dairy products. If you are intolerant to lactose, you will need to eliminate milk, yogurt, ice cream and soft cheese. Most people with lactose intolerance can tolerate up to 1/3 cup of milk and small amounts of fermented dairy like yogurt. Hard cheeses, cream and butter contain very small amounts of lactose and are usually well-tolerated. However, if you are severely lactose intolerant, avoid all dairy products.
Sorbitol
If you are a sorbitol malabsorber, avoid fruits with a high sorbitol content, such as apples, apricots, blackberries, pears, nectarines and plums. Avocado, cherries and lychees also contain small amounts of sorbitol and may be tolerated in small amounts, but you will have to determine your own personal tolerance. Be careful with sugar-free chocolate, candies, gums, mints and ice creams as these products are often sweetened with sorbitol, isomalt, xylitol or mannitol, which can be problematic with sorbitol malabsorption.
References
- Journal of the American Dietetic Association; Fructose Malabsorption and Symptoms of Irritable Bowel Syndrome: Guidelines for Effective Dietary Management; Susan J. Shepherd and Peter R. Gibson; 2006
- Journal of Gastroenterology & Hepatology; Evidence-Based Dietary Management of Functional Gastrointestinal Symptoms: The FODMAP Approach; Peter R Gibson and Susan J Shepherd; October 2009
- "IBS--Free at Last!"; Patsy Catsos; 2009
