Source: USDA ARS, 5/10/22 Healthy adults who eat a diverse diet with at least 8-10 grams of soluble fiber a day have fewer antibiotic-resistant microbes in their guts, according to a study published by Agricultural Research Service scientists and their colleagues in mBio.Microbes that have resistance to various commonly used antibiotics such as tetracycline and aminoglycoside are a significant source of risk for people worldwide, with the widely held expectation that the problem of antimicrobial resistance (AMR)—the term that refers to bacteria, viruses, and fungi that are resistant to antibiotics—is likely to worsen throughout the coming decades. Antimicrobial resistance in
people is largely based in their gut microbiome, where the microbes are known
to carry genetically encoded strategies to survive contact with antibiotics. "And
the results lead directly to the idea that modifying the diet has the potential
to be a new weapon in the fight against antimicrobial resistance. And we're not
talking about eating some exotic diet either, but a diverse diet, adequate in fiber,
that some Americans already eat," explained research molecular
biologist Danielle
Lemay with the ARS Western
Human Nutrition Research Center in Davis, California, and
leader of the study. In this study, the researchers
were looking for specific associations of the levels of antibiotic resistance
genes in the microbes of the human gut with both fiber and animal protein in
adult diets. The researchers found regularly
eating a diet with higher levels of fiber and lower levels of protein,
especially from beef and pork, was significantly correlated with lower levels
of antimicrobial resistance genes (ARG) among their gut microbes. Those with
the lowest levels of ARG in their gut microbiomes also had a greater abundance
of strict anaerobic microbes, which are bacteria that do not thrive when oxygen
is present and are a hallmark of a healthy gut with low inflammation. Bacterial
species in the family Clostridiaceae were the most numerous anaerobes found. But the amount of animal protein
in the diet was not a top predictor of high levels of ARG. The strongest
evidence was for the association of higher amounts of soluble fiber in the diet
with lower levels of ARGs. "Surprisingly, the most
important predictor of low levels of ARG, even more than fiber, was the
diversity of the diet. This suggests that we may want to eat from diverse
sources of foods that tend to be higher in soluble fiber for maximum
benefit," Lemay added. Soluble fiber, as its name
suggests, dissolves in water and is the main type of fiber found in grains like
barley and oats; legumes like beans, lentils and peas, seeds (like chia seeds)
and nuts; and some fruits and vegetables like carrots, berries, artichokes,
broccoli and winter squash. On the other end of the data,
those people who had the highest levels of ARG in their gut microbiomes were
found to have significantly less diverse gut microbiomes compared to groups
with low and medium levels of ARG. "Our diets provide food for
gut microbes. This all suggests that what we eat might be a solution to reduce
antimicrobial resistance by modifying the gut microbiome," Lemay said. In
total, 290 healthy adults participated in the study. "But this is still just a
beginning because what we did was an observational study rather than a study in
which we provided a particular diet for subjects to eat, which would allow more
head-to-head comparisons," Lemay said. "In the end, dietary
interventions may be useful in lessening the burden of antimicrobial resistance
and might ultimately motivate dietary guidelines that will consider how
nutrition could reduce the risk of antibiotic-resistant infections." The Agricultural
Research Service is the U.S.
Department of Agriculture's chief scientific in-house research agency. Daily,
ARS focuses on solutions to agricultural problems affecting America. Each
dollar invested in agricultural research results in $17 of economic impact.
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