What a
difference strain can make
In the world of probiotics, i.e., microorganisms that
provide benefit to their host such as us, there is
something called strain specificity. I know
that this sounds like dull, confusing jargon, but
stick with me, as this is going to be among the most
important emerging issues in overall health.
To illustrate, let’s take the common bacterial
Escherichia coli, or E. coli.
“Escherichia” designates the genus of
bacteria; there are also Escherichia hermanii
and Escherichia vulneris, for example: same
genus, different species. “Coli” is
therefore the species in E. coli.
You and I have strains of E. coli in our
intestines that quietly coexist with us (though it is
among the species that proliferate when small intestinal
bacterial overgrowth, or SIBO, develops.) But
get exposed to say, the O157:H7 E. coli
strain from lettuce contaminated with cow manure,
and you develop horrendous diarrhea and other
complications that can be fatal—same
species, different strain compared to the
E. coli normally inhabiting your intestine.
So bacterial strain can make a world of difference, the
difference between quiet coexistence and death from
E coli. The probiotic Lactobacillus
casei DN-114001 is effective for reducing diarrhea
that occurs after a course of antibiotics, while
Lactobacillus casei Shirota does not—same
species, different strain. In a large clinical trial to prevent infant sepsis (a
life-threatening blood infection), Lactobacillus
plantarum ATCC 202195 cut the incidence of sepsis
nearly in half, while Lactobacillus plantarum
GG did not—same species, different strain.
Choosing the right strain can therefore make the
difference between a marked beneficial response or no
response at all, even literally making the difference
between life and death.
Problem: The majority of commercial probiotics fail
to designate the strains of the microorganisms
contained in their preparations. The Vitamin Shoppe
Probiotic Complex Men’s Formula, for example,
lists Lactobacillus acidophilus, Lactobacillus
plantarum, Lactobacillus bulgaricus,
Bifidobacteria bifidum, and Streptococcus
thermophilus—genus and species, but no
mention of strains. (These are the species commonly
found in yogurt, by the way, especially the
Lactobacillus bulgaricus and the
Streptococcus thermophilus.) It means that,
unless strains are mentioned and compared to the
evidence, we won’t really know if a commercial
probiotic preparation works to achieve health
benefits. We could, of course, trust the manufacturer
and their advisers to choose the strains that have
solid evidence of efficacy behind them, but it
still would be nice to have strains specified
on the labels.
In future, I shall be discussing this issue further
so that we all have better precision and effectiveness
in our choice of probiotics.
(Image courtesy USDA.)
