Title: Alternative Sweeteners

Trehalose 451
ileum (53). Trehalase hydrolyzes trehalose in close proximity to the enterocytes
where the two glucose molecules are transported into the body by a well-known
active transport system (54). Glucose uptake in the small intestine is efficient,
and studies have shown that each 30 cm of jejunum (10% of the total length of
the small intestine) can absorb 20 g of glucose per hour (55). In addition, during
the first hour after digestion, the stomach releases only about 50 g of glucose
into the duodenum (56). Disaccharides are known to retard gastric emptying, and
although trehalose has not been specifically tested, it is likely that it would have
a similar effect (57). Thus all ingested trehalose is hydrolyzed to glucose and
absorbed in the small intestine.
Only a few studies have examined the level of trehalase activity in the gut.
These have not always used the same endpoints or experimental conditions, so
it is not possible to make direct comparisons. It can be inferred from these studies
that, except in a few specific instances, the concentration of trehalase in the small
intestine of humans is sufficient to handle substantial amounts (at least 50 g in
a single ingestion) of trehalose.
Gudmand-Høyer et al. noted that trehalase and lactase activities in the gut
are similar (58). In the experience of the authors, a lactase activity of 6.0 IU/g
protein or less results in malaborption of lactose, whereas activities from 6.0 to
8.0 IU/g protein were considered intermediate and may or may not result in
malabsorption. The authors suggested that it may be appropriate to use a similar
standard for trehalase. They referred to a study of trehalase activity of intestinal
biopsies from 248 Danish patients in which the lowest level of activity in the
group was 8.3 IU/g. Furthermore, no trehalase deficiencies were identified in
more than 500 biopsies specimens of Danish subjects (58).
Welsh described intestinal trehalase activity in 123 Caucasian subjects
ranging in ages from 1 month to 93 years from the southwestern United States
(59). No significant differences in trehalase activity for all age groups or sexbased
differences were found. The lowest recorded values were 7 and 8 IU/g in
two infants 0 to 2 years of age (n 70). No statistically significantly differences
in trehalase activity were found for any age group or sex. Importantly, trehalase
activity did not appear to wane with age.
In a study of 100 consecutive normal biopsy samples from adults (72 men,
28 women), two subjects with low trehalase activity (2.7 and 1.5 IU/g) were
identified (60). It was suggested by these authors that a trehalase value 5
IU/g might result in intolerance of trehalose ingestion, which is similar to the
conclusion of Gudmand-Høyer et al. (58). In a second study, Bergoz tested 16
control subjects for their ability to assimilate trehalose (4). Each subject drank
50 g of glucose in water, followed within 2 days by a similar preparation of
trehalose. Blood glucose values were assayed after ingesting glucose or trehalose,
and the ratios of glucose absorbed were calculated. All control subjects tolerated
both test solutions and assimilated the glucose hydrolyzed from trehalose (ratio
0.70, range, 0.31–1.42); however, the time to peak blood glucose concentra-