Diets high in fiber associated with less antibiotic resistance in gut bacteria: new research

According to new research published in the journal, mBIO, “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…” Soluble fiber is found in foods such as oats, barley, beans, lentils, nuts, seeds (e.g., flaxseed) and some fruits and vegetables (e.g., oranges, apples, pears, guavas, Brussels Sprouts, sweet potatoes, carrots, asparagus, and broccoli).

“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 bacteria, viruses, and fungi that are resistant are 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.” According to the authors of this new research, “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.”

“The researchers found that regularly eating diet with higher levels 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 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.”

Source: Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA). Diets high in fiber associated with less antibiotic resistance in gut bacteria. Davis, CA: ARS, USDA. May 10th, 2022. Available at:

Citation: Oliver A, Xue Z, Villanueva YT, et al. Association of diet and antimicrobial resistance in healthy U.S. adults. mBIO

Published by greengrass50

My name is Christine McCullum-Gomez, PhD, RDN. I am a registered dietitian nutritionist with expertise in environmental nutrition, food and nutrition policy, food and nutrition security, food justice, chronic disease prevention, regenerative & organic agriculture, and sustainable healthy dietary patterns. Currently, I serve on the Editorial Review Board and as a Column Editor for the Journal of Hunger & Environmental Nutrition. I live in Bogota, Colombia with my husband, two teenagers (boy-girl twins), and our dog Honey. My website is: You can follow me on Instagram at:

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