Enterococcus faecium

The Development of Probiotic-Containing Functional Foods 29
beyond inherent general nutrition.” Although specific numbers are not mentioned in
the definition, it is thought that at least 10 9 CFU per day need to be ingested.
Salminen et al. 30 proposed that probiotics be defined as microbial cell preparations,
or components of microbial cells, that have a beneficial effect on the health
and well-being of the host. This definition emphasizes that probiotics can be either
nonviable cells or parts of cells, because probiotics in these forms, as well as certain
fermentation end-products and enzymes, have been shown to exert health benefits. 30
Here, the importance is underlined of understanding the specific functions of probiotics
in the host. In 2001, a joint committee Food and Argriculture Organisation
of the United Nations/World Health Organisation (FAO/WHO) expert consultation
on health and nutritional properties of powder milk with live lactic acid bacteria
redefined probiotics as “live microorganisms that, when administered in adequate
amounts, confer a health benefit on the host,” again highlighting the importance of
viability. The group recognized that probiotics should be capable of exerting health
benefits on the host through their activity in the human body. 1 This definition is
internationally recognized. Viability of probiotics in the final product is important,
especially when it has been documented as one of the prerequisites for immune
effects. 31
Recently, probiotics have been defined as “living microorganisms that resist gastric,
bile, and pancreatic secretions; attach to epithelial cells; and colonize the human
intestine.” 32 The definition of probiotics has changed from the original one of being
a live active culture beneficially affecting the host by improving its intestinal microbial
balance, to the current concept based on the specific effects of clearly defined
strains. This focuses attention on demonstrated clinical effects, which may be mediated
either through probiotic effects on the intestinal immune system or through
modulation of the gut microbiota at specific locations. 33
2.4 Intestinal Microflora and Ecology of the Gut
The human intestinal tract is a nutrient-rich environment inhabited by up to 100 trillion
(10 14 ) microbes. The vast majority reside in the colon, where densities approach
10 11 to 10 12 cells per milliliter, the highest recorded for any microbial habitat. 34
Colonization of germ-free infants starts immediately after birth; they acquire their
microbiota initially from the vagina and feces of their mothers, 35 or from the environment
(in a caesarean delivery), as well as by the diet, genetic background, and
environment of the individual. The diverse microbial community of the human GIT
encompasses both facultative anaerobic and obligate anaerobic microorganisms, 25
and is one of the preferred sources of potential probiotic microorganisms destined
for human use.
The GIT microflora originate in the oral cavity where a complex microbiota
exist, 36 including members of the Prevotella, Porphyromonas, Peptostreptococcus,
Bacteroides, Fusobacterium, Eubacterium, and Desulfovibrio genera. 37 Bacteria
experience large losses in viability in the stomach due to its strong acidic and peristaltic
nature, and so only the most acid-resistant microorganisms survive. 25,38 Less
than 10 3 cells per gram of mainly Streptococcus, Staphylococcus, and Lactobacillus
species are found in the stomach. 38 In the small intestine, low pH, presence of bile,