Chemistry Reference
In-Depth Information
In summary, lactulose is one of the first prebiotics produced, predating the nutri-
tional definition. As a result, it was and is used predominantly as medication. Its
original indications for constipation and hepatic encephalopathy remain the major
uses of this disaccharide. However, as this review shows there are many potential
indications for which lactulose could be used. Further studies will need to be carried
out before such other indications are accepted.
5.3
lACTITol
Lactitol is also derived from lactose through hydrogenation of the parent com-
pound.
87
This sugar alcohol is designated as 4-β-d-galactopyranosyl-d-glucitol or
1:4 B-galactosido-sorbitol.
88
It appears to be about 35 percent as sweet as sucrose,
contains 2 to 3 kcals/g of compound and has better taste qualities than lactulose.
88
It
is also neither hydrolyzed nor absorbed in the intestine, but spills into the large bowel
where it is metabolized by bacteria.
88-90
5.3.1
Physiological and bacteriological Effects
The reaction to lactitol in humans is similar to reaction to lactulose, and the
diarrheic effects are also putatively related to osmotic influences as in the case of
lactulose. A study of young Japanese women calculated that a dose above 0.36 g/kg
of a single ingested amount of lactitol would induce diarrhea. This amount was half
that tolerated with a single ingestion of lactose.
91
Lactitol in the colon leads to the
induction and release of the motility- and appetite-regulating peptide YY. However,
the effect appears to be less in humans than in rats.
92
No data exist whether motility
in the colon is as affected as for lactulose.
12,92
The effects on microflora also resemble the effects of lactulose described in
Section 5.2.
17
Ballongue et al.
17
reported a comparative double-blind, placebo-con-
trolled trial in human volunteers of 20 g/day lactitol against lactulose. These authors
found similar outcome with both, but the effects of the latter were more distinct and
were of faster onset. In this case, both bifidobacteria and lactobacilli were found
to be increased and bacteroides and clostridia species were decreased.
17
Fecal pH
was reduced equally by both lactulose and lactitol. Short-chain fatty acids resulted
in increased acetic acid, but only about half were found with lactulose. The prote-
olytic short-chain fatty acid valeric acid was decreased somewhat more by lactulose
than by lactitol. In addition, a number of enzymes, azoreductase, 7α-dehydroxylase,
β-glucuronidase, nitroreductase, and urease, were significantly reduced compared
with placebo, but again lactulose was more efficient.
Conflicting
in vitro
studies found that some monosaccharides and disaccharides
did increase carbohydrate-derived short-chain fatty acids.
3,93
In fact, in another
in vitro
fermentation system, it was found that both bacteroides and bifidobacte-
ria were reduced but butyrate was increased by lactitol.
94
Similarly, it was shown
in a rat model that lactitol in combination with polydextrose raised butyrate lev-
els and induced secretion of mucosal IgA better than individual compounds.
95
In
