Excessive intake of sorbitol, a widely used sweetener in "sugar-free" products such as chewing gum and sweets, may lead to weight loss and diarrhoea, German doctors report.

The laxative effects of excessive sorbitol consumption are well-known. Indeed, statements to this effect are noted on the packaging.

According to two case studies in this week's British Medical Journal, excessive intake above about 20 grams per day of the sweetener may also lead to unintended weight loss in the region of about 20 per cent of usual body weight, states Juergen Bauditz and colleagues from Berlin's Charite Universitatsmedizi.

The German doctors quote two case studies - the first involved a 21 year-old woman who chewed large amounts of sugar-free gum, giving an approximate daily dose of 18-20g sorbitol. The second case involved a 46 year-old man who consumed large amounts of sugar-free gum and sweets, giving an average daily dose of around 30g sorbitol.

Both cases reported chronic diarrhoea, abdominal pain and severe weight loss.

Bauditz and colleagues report that normal bowel movements were resumed and the patients gained weight after starting a sorbitol-free diet.

"As possible side effects are usually found only within the small print on foods containing sorbitol, consumers may be unaware of its laxative effects and fail to recognise a link with their gastrointestinal problems," wrote the authors.

The Food and Drink Federation (FDF) was quick to defend the sweetener. A spokesperson told FoodNavigator.com: "Only two cases were highlighted in the British Medical Journal report and both involved excessive consumption of sugar-free sweets and gum.

"The safety of sorbitol has been thoroughly reviewed by health and regulatory bodies around the world, and it has been approved for use in numerous countries including the USA, EU, Australia, Canada and Japan

"By law manufacturers have to label products containing sorbitol and other polyols with the unambiguous statement, "Excessive consumption may produce laxative effects.""

A similar statement was issued by a spokesperson for the Wrigley Company, who is quoted by the BBC as saying: "Sorbitol occurs naturally in a wide variety of fruits and berries including pears, plums, cherries, dates, apricots, peaches and apples.

"It is well documented in medical literature, with studies going back more than 20 years, that excessive consumption of polyols, such as sorbitol, can have a laxative effect in some individuals."

"The safety of sorbitol has been thoroughly reviewed by health and regulatory bodies, including the WHO/FAO Joint Expert Committee on Food Additives."

Source: British Medical Journal
12 January 2008, Volume 336, Pages 96-97, doi:10.1136/bmj.39280.657350.BE
"Lesson of the week: Severe weight loss caused by chewing gum"
Authors: J. Bauditz, K. Norman, H. Biering, H. Lochs, M. Pirlich