Nutritional and Health Aspects of Sweeteners - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 335

Many healthy individuals are intolerant of sorbitol and develop abdominal cramping and diar-
rhea with less than the usual laxative dose (Badiga et al. 1990). It has been suggested that more than
30% of healthy adults, irrespective of ethnic origin, cannot tolerate 10 g of sorbitol (Jain et al. 1987).
Certain other patients are especially sensitive to the gastrointestinal effects of sorbitol; for
example, diabetics can be prone to sorbitol intolerance because of altered gastrointestinal transit
time and motility. Some of them also have a higher consumption of sorbitol-containing dietary
foods. Patients on chronic hemodialysis can be predisposed to sorbitol intolerance as a result of
carbohydrate malabsorption (Coyne and Rodriguez 1986).
Some cases of idiopathic colonic ulcers in patients with renal failure are due to the effects of
sorbitol. Five cases of extensive mucosal necrosis and transmural infarction of the colon have been
reported after the use of kayexalate (sodium polystyrene sulfonate) and sorbitol enemas to treat
hyperkalemia in uremic patients (Lillemoe et al. 1987). They also studied the effects of kayexalate
sorbitol enemas in normal and uremic rats and concluded that sorbitol was responsible for colonic
damage and the injury was potentiated in uremic rats. When sorbitol alone or kayexalate sorbitol
was given, extensive transmural necrosis developed in 80% of normal rats and in all uremic rats.
Ruskoné-Fourmestraux et al. (2003) aimed at evaluating the gastrointestinal tolerance to an
indigestible bulking sweetener containing sugar alcohol (MTL) using a double-blind random cross-
over study. MTL is a sugar alcohol produced by hydrogenation from starch hydrolyzates that have a
high content of natural disaccharide maltose. After oral ingestion, MTL is slowly hydrolyzed by the
enzymes of the small intestine into its constituent monomers—glucose and sorbitol. The metabolism
of MTL is therefore similar to that of sorbitol. In order to simulate their usual pattern of consump-
tion, 12 healthy volunteers ingested MTL or sucrose throughout the day, either occasionally (once a
week for each sugar—irst period) or regularly (every day for two 9-day periods—second period).
In both patterns of consumption, daily sugar doses were increased until diarrhea and/or a grade 3
(i.e., severe) digestive symptom occurred, at which the dose level was deined as the threshold dose
(TD). In the irst period (occasional consumption), the mean TD was 92 ± 6 g with MTL and 106 ±
4 g with sucrose ( P = 0.059). The mean intensity of digestive symptoms was 1.1 and 1.3, respectively
( P = NS). Diarrhea appeared in six and one subjects, respectively ( P = 0.035). In the second period
(regular consumption), the mean TD was 93 ± 9 g with MTL and 113 ± 7 g with sucrose ( P = 0.008).
The mean intensity of digestive symptoms was 1.7 and 1.2, respectively ( P = NS). However, diar-
rhea appeared in eight and three subjects, respectively ( P = 0.04). MTL and sucrose TDs between
the two periods were not different. Ruskoné-Fourmestraux et al. (2003) reported that occasional or
regular consumption of MTL is not associated with severe digestive symptoms; in both patterns of
MTL consumption, diarrhea frequency is higher, but it appeared only for very high doses of MTL,
much greater than those currently used. MTL does not lead to intestinal lora adaptation after a
9-day period of consumption.
Other MTL tolerance studies include the work of Leroy (1982) and Koizumi et al. (1983), dem-
onstrating that, in healthy and diabetic subjects, MTL is tolerated up to 30-50 g/day after adapta-
tion. Higher doses cause diarrhea.
Stool excretion after the ingestion of sugar alcohols is negligible, indicating that the sugar alco-
hols reaching the large intestine are almost completely digested by the colonic lora (Beaugerie et al.
1990). However, this malabsorption causes certain side effects, as the fermentation of unabsorbed
sugar leads to latulence. In addition, as polyol molecules are osmotically active, diarrhea may
occur when the capacity of the colonic lora to ferment these low-molecular-weight carbohydrates
is exceeded and osmotic stress rises in the intestinal lumen (Hammer et al. 1989; Saunders and
Wiggins 1981).
The capacity to ferment unabsorbable sugars, such as lactose and lactulose, and to reduce their
laxative effects can, however, be increased by the regular ingestion of these sugars, which results in
changes in the metabolic activity of the colonic lora, especially a reduced excretion of hydrogen in
the breath (H 2 ; Florent et al. 1985; Flourié et al. 1993; Launiala 1968; Perman et al. 1981). Langkilde