Healthy adults who eat a variety of foods with at least 8-10 grams of soluble fiber per day have fewer antibiotic-resistant bacteria in their guts, according to a study published by Agricultural Research Service scientists and their colleagues. mBio.
Microbes resistant to various commonly used antibiotics such as tetracyclines and aminoglycosides are an important source of risk to humans worldwide, widely believed to be the problem of antimicrobial resistance (AMR)—a term that refers to bacteria, viruses, and. Antibiotic-resistant fungi — likely to worsen over the next few decades.
Antimicrobial resistance in humans is largely based on their gut microbiome, where microbes carry genetically encoded strategies to survive exposure to antibiotics.
“And the results lead directly to the idea that changing diet has the potential to be a new weapon in the fight against antimicrobial resistance. And we’re not talking about eating some exotic food, but a varied diet, with enough fiber, which some Americans already eat,” Daniel Lemme, a molecular biologist at the ARS Western Human Nutrition Research Center in Davis, California, and the study leader, explains.
In this study, researchers looked for specific associations between the levels of antibiotic resistance genes in human gut microbes with dietary fiber and animal protein in adults.
Researchers found that regular high levels of fiber and low levels of protein, particularly beef and pork, were significantly associated with lower levels of antimicrobial resistance genes (ARG) in their gut microbes. Those with the lowest levels of ARG in their gut microbiome also had higher abundances of strict anaerobes, which are bacteria that do not thrive in the presence of oxygen, and are characteristic of a healthy gut with less inflammation. The most numerous anaerobes have been found among bacterial species in the family Clostridiaceae.
But the amount of animal protein in the diet was not the top predictor of high levels of ARG. The strongest evidence was the association of higher amounts of soluble fiber in the diet with lower levels of ARG.
“Surprisingly, the most important predictor of lower levels of ARG, even more so than fiber, was dietary variety. This suggests that we should eat from a variety of food sources that are high in soluble fiber for maximum benefit,” Lemme added.
Soluble fiber, as its name suggests, dissolves in water and is the main type of fiber found in grains such as barley and oats; beans, lentils and peas, seeds (like chia seeds) and nuts; and some fruits and vegetables such as carrots, berries, artichokes, broccoli and winter squash.
At the other end of the data, those with the highest levels of ARG in their gut microbiome were found to have significantly less diverse gut microbiomes than groups with low and moderate levels of ARG.
“Our diets provide food for gut microbes. All of this suggests that what we eat may be a solution to reducing antimicrobial resistance by altering the gut microbiome,” Lemme said.
In total, 290 healthy adults participated in the study.
“But it’s still a start because what we did was an observational study rather than a study where we provided a specific diet to eat, which would allow for more head-to-head comparisons,” Lemme said. “Ultimately, dietary interventions may be effective in reducing the burden of antimicrobial resistance and may ultimately inspire dietary guidelines that consider how nutrition can reduce the risk of antibiotic-resistant infections.”