Fundamental Food Microbiology, Third Edition - Fuad Fathir

INTESTINAL BENEFICIAL BACTERIA 219
studied for the possible beneficial effects and many products do not have high viable
cell numbers required to produce benefit (Table 15.1). As a result, doubts about the
beneficial effect of these products remain.
A. Standard of Identity 12
Recently, there has been a concerted effort to develop a scientific basis for probiotic
bacteria. Through a joint effort by scientists in this area, a standard of identity
has been established for the beneficial probiotic bacteria, especially those from
the genus Lactobacillus. This includes the ability to (1) adhere to GI epithelial
cells; (2) interfere with adherence of enteric pathogens to GI epithelial cells; (3)
persist and multiply in the GI tract without disturbing the normal microbial
balance; (d) produce antibacterial metabolites; (e) coaggregate; (f) form a normal
flora of the GI tract; and (g) be safe to the hosts. Following a critical evaluation
of the data of scientific studies, five strains of lactobacilli are considered effective
for use as probiotics: (1) Lab. acidophilus NCFM, (2) Lab. casei shirota, (3) Lab.
casei CRL431, (4) Lab. rhamonosus GG, and (5) Lab. reuteri MM53. In the last
few years, several other species/strains of Lactobacillus and Bifidobacterium have
been included in the list.
B. Scientific Status Summary 13
A scientific status summary has recently been published, listing the diverse species
currently being used by probiotic product manufacturers and their claims for the
bacterial species they are using. Some of the species include Lab. acidophilus,
Lab. bulgaricus, Lab. casei, Lab. fermentum, Lab. johnsonii, Lab. lactis, Lab.
paracasei, Lab. plantarum, Lab. rhamonosus, Lab. reuteri, Bif. bifidus, Bif. longum,
Bif. brevis, Streptococcus thermophilus, and some yeasts. Their claims are
not supported by valid scientific studies and have created disbelief among consumers.
It was suggested in the report that, to overcome the current controversy,
future research should be directed toward (1) identifying the phylogeny of a strain,
(2) conducting health benefit studies with humans, (3) explaining the exact mechanisms
by which a strain produces a benefit, (4) finding the dose level of viable
cells and duration required for a benefit; (5) determining the ability of a strain to
adhere to GI epithelial cells; (6) studying the influence of a probiotic strain on
normal GI tract microflora, and (7) determining the proper and effective delivery
systems of a probiotic strain.
There is no doubt that some bacterial species and strains do have beneficial
influence on the health of the GI tract and probably the overall health of humans.
But they have to be identified through valid scientific studies. The indiscriminate
use, imaginative claims, and unscrupulous methods of a few have created the disbelief.
A move for current collaborative scientific studies to define the standards of
identity of probiotic strains, as well as the suggestions outlined in the status report
regarding the research requirements before claiming a strain to have benefits, are
the correct steps to remove the myths surrounding beneficial properties of probiotic
bacteria.
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