Taking antibiotics regularly disrupts gut health, increases risk of developing IBD

NEW YORK — People over 40 who regularly take antibiotics are more likely to develop inflammatory bowel disease, a new study warns.

Researchers from NYU Langone Health say the risk seems to be cumulative and reaches its greatest point one to two years after taking a course of medication, as well as after taking antibiotics which target gut infections. There is also growing evidence that environmental factors play a role in the development of inflammatory bowel disease (IBD).

Roughly seven million people worldwide have the condition and study authors predict that number will rise over the next decade. One factor tied to the risk of IBD among younger patients — a condition which includes Crohn’s disease and ulcerative colitis — is the use of antibiotics. However, study authors admit it’s been unclear if the same factors applied to older people.

The research team drew on national medical data for Danish citizens over 10 years-old who did not have IBD from 2000 to 2018. They specifically wanted to know if the timing and dose of antibiotics plays a factor in the development of IBD.

This study included more than 6.1 million people, with just over half being female. In total, 5.5 million (91%) received a prescription for at least one antibiotic between 2000 and 2018. During the study period, doctors diagnosed more than 36,000 new cases of ulcerative colitis and over 16,800 new cases of Crohn’s disease.

Compared with no antibiotic use, the study finds that using these drugs displayed a clear connection to a higher risk of developing IBD, regardless of age. However, older patients had the highest risk.

Taking more prescriptions increases IBD risk even more

Those between 10 and 40 years-old were 28 percent more likely to develop IBD. Meanwhile, 40 to 60-year-olds were 48 percent more likely to have the condition, while those over 60 were 47 percent more likely to have IBD.

The risks were slightly higher for Crohn’s disease than they were for ulcerative colitis — 40 percent among 10 to 40-year-olds, 62 percent among 40 to 60-year-olds, and 51 percent among seniors over 60. Researchers say the risk seemed to build up, with each subsequent course of medication adding an additional 11-percent, 15-percent, and 14-percent higher risk, according to each age range.

The findings also show that the highest risk was found among those prescribed five or more courses of antibiotics. These patients had a 69-percent heightened risk among 10 to 40-year-olds. The risk doubled among 40 to 60-year-olds and was 95 percent higher among those over 60.

Corresponding author, Dr. Adam Faye, says timing plays an influential role in this process. The highest risk for IBD occurred 12 to 24 months after using antibiotics. Each subsequent year thereafter, the risk for IBD dropped off. The highest risk of IBD came after using nitroimidazole and fluoroquinolone, which are antibiotics used to treat gut infections.

Dr. Faye says these drugs are called “broad spectrum antibiotics” because they indiscriminately target all microbes in the gut, not just those that cause disease. Nitrofurantoin was the only antibiotic type that did not increase IBD risk at any age.

Narrow spectrum penicillins also increased the risk of IBD, but the severity was much less severe. Researchers say this adds weight to the notion that changes in the gut microbiome may play a key role and that many antibiotics have the potential to completely change the makeup of microbes in the gut.

What’s causing antibiotics to harm the gut?

The team does note that their results are observational, and they can’t establish a definitive cause for this problem. However, they believe there are some “plausible” biological explanations for their findings. Part of the problem may be the reduction in both the resilience and range of microbes in the gut microbiome that typically happens due to aging.

“Furthermore, with repeated courses of antibiotics, these shifts can become more pronounced, ultimately limiting recovery of the intestinal microbiota,” researchers say in a media release.

Faye says limiting prescriptions for antibiotics may not only help to curb antibiotic resistance but may also help lower the risk of IBD.

“The association between antibiotic exposure and the development of IBD underscores the importance of antibiotic stewardship as a public health measure, and suggests the gastrointestinal microbiome as an important factor in the development of IBD, particularly among older adults.”

The findings appear in the journal Gut.

South West News Service writer Stephen Beech contributed to this report.

YouTube video