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Hypercholesterolemia
Evidence
is accumulating that probiotic bacteria may have a beneficial effect on
blood lipid levels. Taylor
and Williams described the effects of probiotics and prebiotics on
blood lipids in 1998. Their review notes that there are many limitations
in study designs with early studies "using excessive volumes of yogurt
and failing to control background dietary intake and physical activity
levels". One study in hypercholesterolemic mice showed that administration
of low levels of L. reuteri for seven days decreased total cholesterol
and triglyceride levels by 38% and 40%, respectively, and increased HDL:
LDL ratio by 20%. (31) Although the few human clinical studies done were
of relatively short duration, lipid levels were affected similarly. (4)
Hyperlipidemic patients who were administered L. sporogenes experienced
a mean 32% reduction in total cholesterol and 35% reduction in LDL cholesterol
over a 3-month period. (3) In a well- controlled 8-week clinical trial
in overweight subjects, daily consumption of 450mL of yogurt fermented
with S. thermophilus and E. faecium resulted in an 8.4% reduction in LDL
and an increase in fibrinogen levels. (34) Clearly, additional studies
are needed to determine the utilization of probiotics in controlling blood
lipid levels.
Consuming
probiotics as food can help to increase calcium and protein intake but
it is questionable as to whether probi otic
food products improve the chance that they reach the intestine alive (see
page 13). Consumers need to check product labels to identify the type of
probiotic strain present in food products. If needed, contact the manufacturer
to determine effective doses and disease conditions that the probiotic
strain was tested on.
Most
probiotics are GRAS (generally recognized as safe) but as noted by Goldin,
there are some reports of bacteraemias and endocarditis related to the
use of Lactobacillus in severely immunocompromised individuals. (35) Therefore,
HIV-positive people should consult their physician prior to using probiotics.
Reid
offers a mini-review
of the scientific basis for probiotics such as Lactobacillus
and notes that it is time for probiotics to be taken seriously. (36) We
still, however, need the clinical trials and data that give a basis and
mechanism of action for human use.
In
spite of the problems with dosage and viability of probiotic strains, lack
of industry standardization and potential safety issues, there is obviously
considerable potential for the benefits of probiotics over a wide range
of clinical conditions. (4) Ongoing basic research will continue to identify
and characterize existing strains of probiotics, identify strain-specific
outcomes, determine optimal doses needed for certain results and assess
their stability through processing and digestion. Gene technology will
certainly play a role in developing new strains, with gene sequencing allowing
for an increased understanding of mechanisms and functionality of probiotics.
Industry-centered research will focus on prolonging the shelf-life and
likelihood of survival through the intestinal tract, optimizing adhesion
capacity and developing proper production, handling and packaging procedures
to ensure that the desired benefits are delivered to the consumer.
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