Getting enough overall and soluble fiber in your diet may help reduce antibiotic resistance — a situation in which antibiotics become less effective at treating bacterial infections — according to a new study published in mBio, the journal of the American Society for Microbiology.
Soluble fiber is a category of dietary fiber that can be dissolved in water, forming what is sometimes described as a gel-like substance in the digestive tract. Dietary fiber refers to carbohydrates that can’t be easily broken down by the digestive system, passing into the colon in their original form. Once in the colon, dietary fiber may act as food for “good” bacteria that produce beneficial substances that are absorbed by the body. While both of the major categories of dietary fiber — soluble and insoluble — are considered to be beneficial, their specific benefits may vary. Insoluble fiber, which doesn’t dissolve in water, is sometimes referred to as “roughage” and may help provide bulk to stools and promote digestive regularity — in addition to serving as food for helpful bacteria. While soluble fiber may also encourage digestive regularity, it’s known to have distinct benefits like reducing blood cholesterol levels and possibly improving blood glucose control. Unfortunately, studies show that most Americans — including those with diabetes — don’t consume enough fiber, either soluble or insoluble.
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For the latest study, researchers were interested in examining the role of dietary factors in the growing problem of antibiotic resistance — when antibiotics don’t treat bacterial infections as effectively as they previously did, indicating that harmful bacteria have adapted to resist these drugs. Despite the growing threat of antibiotic resistance around the world — which has contributed to many infection deaths, and is only expected to get worse — there haven’t been many studies on the role that diet may play in this risk. Some previous studies have shown that people in rural, non-industrialized societies have gut bacteria with completely different genetic profiles when it comes to likely antibiotic resistance, with dietary factors as a potential explanation for this difference.
A total of 290 adults — 140 men and 150 women — were recruited in the area around Davis, California, and underwent what’s known as metagenomic sequencing, meaning that the genetic profile of their gut bacteria was analyzed. Most participants (205) were white, but some also identified as Hispanic (38), Asian (32), or Black (13). Participants were also grouped according to their age and body-mass index (BMI, a measure of body weight that takes height into account). Each participant completed a detailed food frequency questionnaire, which the researchers used to estimate their intake of various components, including dietary fiber.
Dietary fiber, animal protein linked to levels of antibiotic resistant genes
The researchers found a wide range in what are known as antibiotic resistance genes (ARGs) among participants — genes found in gut bacteria that have been linked to antibiotic resistance in previous studies. In fact, these genes were over three times as abundant in the gut bacteria of some participants compared with others. There was a clear pattern of dietary factors linked to antibiotic resistant genes. Participants who consumed more total and soluble fiber tended to have lower levels of these genes, while participants who consumed more protein — especially from beef and pork — tended to have higher levels of antibiotic resistant genes. (It’s possible that people who ate more beef and pork were actually consuming more antibiotics from these food sources, but this isn’t something that the researchers measured.)
But surprisingly, the researchers didn’t find any link between overall healthy eating patterns — as indicated by the healthy eating index (HEI), which they calculated based on participants’ food frequency questionnaire responses — and antibiotic resistant genes. Only dietary fiber and animal protein intake — not fruit or vegetable consumption, fat intake, or any other dietary factor — were linked to participants’ likely antibiotic resistance.
The researchers concluded that a higher fiber intake may help shift the balance of gut bacteria away from organisms known to encourage inflammation and antibiotic resistance. “Ultimately, future work may use research-based dietary guidelines to reduce the incidence of antimicrobial resistance, thus lifting an immense burden on health care systems worldwide,” they wrote.
Want to learn more about dietary fiber? Read “Find Out About Fiber: What It Is and Why You Need It.”
