Short Chain Fatty Acids SCFAS and Nutrition |
Short Chain Fatty Acids (Falk Symposium, 73) Short chain fatty
acids (SFCA) are synthesized
by the colonic microflora primarily from non-absorbed
carbohydrate; there is also some limited production from
non-absorbed protein. In contrast, SFCA
are not normally present in the diet. During the past 15
years SFCA have attracted considerable interest in human
nutrition, physiology and pathophysiology as a result of
the realization that SFCA represent an important mechanism
for carbohydrate and calorie conservation and may play a
role in various types of colitides and possibly in colonic
neoplasia. In addition, SFCA, produced in large amounts by
ruminants and other herbivores, have long been the
province of veterinary physiologists. This book is based
upon the presentations at the 73rd Falk Symposium held in
Strasbourg, France, September 8--10, 1993, which brought
together researchers and clinicians from five continents.
It provides an excellent statement of the present
state-of-the-art knowledge of SFCA.
Physiological and Clinical Aspects of Short-Chain Fatty Acids This is the first
comprehensive volume to look at the importance of short-chain
fatty acids in digestion, the function of the
large intestine and their role in human health. Short-chain
fatty acids are the major product of
bacterial fermentation of dietary carbohydrates in the
human and animal large intestine. They represent the
major end products of digestive processes occurring in
the caecum and large intestine. As such, they form an
important dietary component and it is increasingly
recognised that they may have a significant role in
protecting against large bowel cancer and in metabolism.
Prepared by an international team of contributors who
are at the forefront of this area of research, this
volume will be an essential source of reference for
gastroenterologists, nutritionists and others active in
this area.
Short-chain
fatty acids (SCFAs) are the main metabolic
products of anaerobic bacterial fermentation in the
intestine. In addition to their important role as fuel
for intestinal epithelial cells, SCFAs modulate
different processes in the gastrointestinal (GI) tract
and in other tissues such as adipose and immune
tissues. In this chapter, we first present a brief
description of basic aspects of SCFA physiology, such
as production, absorption and metabolism. The main
mechanisms by which SCFAs act on cells and the effects
of these fatty acids in isolated leukocytes are then
discussed. We also highlight the results obtained by
studies performed in vivo using SCFAs
in the treatment of inflammatory pathologies. A brief
discussion about the perspectives in this research
field is presented at the end of the chapter.
The induction of
apoptosis in mammalian cells by bacteria is well
reported. This process may assist infection by pathogens
whereas for non-pathogens apoptosis induction within
carcinoma cells protects against colon cancer. Here,
apoptosis induction by a major new gut bacterium,
Atopobium minutum, was compared with induction by
commensal (Escherichia coli K-12 strains), probiotic
(Lactobacillus rhamnosus, Bifidobacterium latis) and
pathogenic (E. coli: EPEC and VTEC) gut bacteria within
the colon cancer cell line, Caco-2. The results show a
major apoptotic effect for the pathogens, mild effects
for the probiotic strains and A. minutum, but no effect
for commensal E. coli. Short chain fatty acids (SCFAs)
are the main fermentation products of intestinal
saccharolytic bacteria in the colon and are thought to
protect against colon cancer by inducing apoptosis in
transformed cells. Our results confirmed that SCFAs
caused morphological changes in human colonic carcinoma
cell line (Caco-2) indicative of apoptosis. Analysis of
various molecular markers of apoptosis (Bcl-2, caspases,
cytochrome c release and cell membrane FAS levels)
strongly indicated that effect.
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