Chemistry Reference
In-Depth Information
2001). This truncated enzyme performed equally well at lactose concentra-
tions ranging from 10 to 40%. Thus, there is much scope for modifying the
chain length of oligosaccharides synthesized and to do this with high yields.
A number of the health benefits of lactose derivatives are well estab-
lished, including the pharmaceutical applications of lactulose and lactitol as
laxatives and treatments for hepatic encephalopathy. It is clear too that
ingestion of GOSs and lactulose can modify the composition and activity of
the intestinal microbiota, and there is some evidence also for prebiotic effects
of lactitol and lactosucrose.
Increasing the numbers of bifidobacteria or lactobacilli in the intestinal
microbiota of individuals with an unfavourable intestinal microbial balance
appears with our current understanding of the human intestinal microbiota to
be a reasonable approach to promoting intestinal health. However, basic
research into the composition and role of different microbial populations
within the intestinal microbiota in health and disease is an essential prerequisite
for the development of appropriate prebiotic strategies. Little is currently
known of the sub-genus changes in bifidobacterial populations that can be
induced by non-digestible carbohydrates, or if such changes are important in a
health context. A better understanding of what constitutes a "healthy" intest-
inal microbiota composition, and which microbial groups and activities are
definitively involved in health and disease, will allow the development of
prebiotics with specifically targeted health effects in the future. The recent
research showing how infant formulae supplemented with GOSs can emulate
many of the effects of human milk oligosaccharides on the infant microbiota
and faecal consistency provides encouraging evidence for a useful role in infant
nutrition. The challenge remains to link the observed changes in the intestinal
microbiota with clinical end-points that clearly demonstrate a health benefit.
The galactose moiety in oligosaccharides is important in mammalian
cell biology (Kobata, 1996). There is considerable interest in the development
of novel galactosyl structures. This is evidenced by the emergence of a large
number of glycoscience companies developing carbohydrate-based drugs.
For example, there are opportunities to develop cost-effective manufacturing
processes
for
fucose-containing
and
N-acetylglucosamine-containing
galacto-oligosaccharides.
The fact that lactose derivatives are non-digestible and are fermented by
the intestinal microbiota to SCFA possibly underpins many of the potential
health benefits of these compounds. There is preliminary evidence for a range
of health benefits, including improved mineral absorption, protection against
colorectal cancer and positive impacts on insulin resistance and serum lipid
concentrations. Further studies to elucidate mechanisms of action and to
demonstrate clinical benefits in controlled feeding studies are certainly
warranted.
