38 • DECEMBER 2021
Your medications
aren’t working
The medicines doctors prescribe
for various conditions don’t always
work, and in some cases, the gut
microbiome may be to blame. Just as
microbes break down the fibre and
starches in our food, they can also
break down pharmaceuticals, making
them act unpredictably.
In fact, a 2019 study from
researchers at the Yale University
School of Medicine looked at 271
drugs taken orally and found that the
gut microbiome affected two thirds of
them, with the bacteria consuming
about 20 per cent of their active
ingredients. That means, for example,
that if you have too much Eggerthella
lenta—a bacterium found in about one
third of us—the commonly prescribed
digoxin might not help your heart
disease symptoms.
This effect on medicine has even
larger implications for cancer
treatment. Recently, researchers
found that the gut microbiome can
affect the progression of some types
of cancer, and that it also affects who
responds to immunotherapy and
bone marrow transplants.
All of the above has given birth to a
new field: pharmacomicrobiomics, the
study of how your gut microbiome
affects a drug’s actions. In ten to 15
years, your doctor may be able to test
your microbiome through a stool
sample and then modulate the dose—
or possibly prescribe a probiotic—to
make your pills work better.
And clinical trials are currently
investigating whether cancer patients
are more likely to survive if they’re
given tailored probiotics, a special
diet, or a fecal transplant—a small
bit of poop from someone else that
could reset your gut microbiome.You struggle
with your weight
“Two decades ago, we thought that
obesity and metabolic disorders
were all about how much you ate,”
says Chang. “But it turns out that the
gut microbiome seems to play an
important role.”
The connection is clearest in
mice: when researchers from the
Washington University School of
Medicine transplanted stool samples
from obese and thin people into the
rodents, the animals who received
fecal transplants from the obese
participants gained more weight and
put on more fat than the ones who
received them from the healthier
participants, even when the mice all
ate the same low-fat diet.
There’s some evidence from humans,
too: for a study two years ago, Belgian
researchers gave people who had
insulin resistance and were overweight
or obese a bacterium that’s more
common in the guts of lean men.
Similar to the mice, the new bacteria
lowered participants’ insulin resistance,
and they lost more weight and fat than a
placebo group.THE ULTIMATE GUIDE TO YOUR GUT