Title: Alternative Sweeteners

Tagatose 117
The intestines of both pigs and humans harbor bacteria that produce butyrate
as the fermentation end-product. d-Tagatose is a rather rare sugar for intestinal
bacteria and is only fermented by a limited genera of bacteria, enterococci,
lactobacilli, and, obviously, some butyrate-producing intestinal bacteria. Other
fibers or undigested carbohydrates are either not a substrate for butyrate-producing
bacteria or are competing for the delivered substrate favoring growth of other
bacteria. A reasonable explanation for the butyrate-inducing effect of d-tagatose
is that butyrate-producing bacteria are favored over most other bacteria when
tagatose is supplied. The adaptation seen with ingestion of d-tagatose in both
pigs and human volunteers is probably due to selection of butyrate-producing
bacteria in the colon. The in vivo absorption study in pigs showed that the adaptation
or selection of bacteria takes place within 12 hr. Similarly, the in vitro study
with human feces indicates selection of bacteria within 48 hr of incubation.
Many studies have documented an important role of butyrate in the colon
because it is the major and preferred fuel for the colonic epithelium (25) and
plays an important role in the control of proliferation and differentiation of colonic
epithelial cells (20). In contrast to the preceding effects on the normal epithelium,
butyrate arrests growth of neoplastic colonocytes (26) and also inhibits
the preneoplastic hyperproliferation induced by tumor promoters in vitro (21).
The lactobacilli and lactic acid bacteria are important inhabitants of the intestinal
tract of man and animals with functional benefits like maintenance of the
normal microflora, pathogen interference, exclusion and antagonism, immunostimulation
and immunomodulation, anticarcinogenic and antimutagenic activities,
deconjugation of bile acids, and lactase presentation in vivo (27). A number
of studies on probiotic bacteria have shown that it is difficult for these bacteria
to colonize the human colon; that is, after stopping the supply of probiotic bacteria
in the diet, they disappear. This makes it more obvious to selectively feed the
Lactobacillus already present in the colon.
On the basis of the preceding documented butyrate stimulation and selection
of bacteria in the colon, d-tagatose is a promising prebiotic food bulk sweetener.
E. Human Tolerance
Extensive human clinical testing has been conducted on d-tagatose to ensure
safety and tolerance (18, 28–34). Testing included a 14-day trial with 30 g given
in a single daily dose, an 8-wk trial with a 75-g daily dosage given as three 25g
doses, and a 12-month trial with a 45-g daily dosage given as three 15-g doses.
Because d-tagatose is malabsorbed, gastrointestinal effects similar to those of
other undigested sugars would be expected. Unabsorbed molecules in the large
intestine retain colonic fluid and increase water content in the feces, contributing