Over 40 and taking antibiotics? Here’s what you need to know about your gut

Researchers found that over-40s who have taken antibiotics are nearly 50 per cent more likely to develop inflammatory bowel disease between one and five years later.

We’ve all taken antibiotics at some point. The miracle drugs have saved many millions of lives since the pills were developed in the 1940s, and helped countless others with troubling infections. Recent concern has been (rightly) been about their overuse – which can lead to less effectiveness or “resistance” from harmful new bacteria. But a study released this week is now suggesting that taking antibiotics might actually be detrimental to the health of people in midlife.

Researchers from New York University and Aalborg University in Denmark found that over-40s who have taken antibiotics are nearly 50 per cent more likely to develop inflammatory bowel disease (IBD) between one and five years later. IBD includes the illnesses Crohn’s disease and ulcerative colitis. According to the study, the more antibiotics a person took, the greater their risk. Someone who had been prescribed antibiotics five or more times had more than double the risk of IBD.

“The data shows a clear association between exposure to antibiotics and inflammatory bowel disease,” says Willen Van Schaik, director of the Institute of Microbiology and Infection at the University of Birmingham. “This is probably because the use of antibiotics will change your gut microbiome in a way that will cause an inflammatory response.”

Adam Faye is assistant professor of medicine and population health at NYU Langone Health in New York, an expert in IBD and the lead researcher of the latest study. “We think that perhaps the gut microbiome may become less resilient as we age, meaning antibiotics or other changes can induce more lasting change,” he says.

Here’s what you need to know about the findings.

I’m over 40 and I’ve taken antibiotics. Should this news concern me?

Firstly, there’s no need to panic. “It’s important to remember that antibiotics definitely won’t inevitably cause inflammatory bowel disease,” says Van Schaik.

While IBD is serious and on the rise – UK cases went up by 33 per cent between 2006 and 2016 – it’s still not that common. Around one in 123 people in the UK have either Crohn’s disease or ulcerative colitis. And a proportion of current sufferers will, points out Van Schaik, be people whose disease was caused by past use of antibiotics.

We also know that antibiotics are not the only trigger for IBD. Genetics and lifestyle issues such as stress, smoking or taking ibuprofen long-term can also play a role. All this means that even a doubling of risk means that your personal chance of developing the disease because of taking antibiotics won’t be anywhere near as high as one in 61.

My doctor has prescribed antibiotics – should I take them?

Yes. Professor Adam Faye says: “The take-home message from our study is definitely not to stop, or not take antibiotics when needed. Antibiotics can be life-saving.”

I’m worried. Should I stop my course halfway through?

Absolutely not. Faye says: “The full course of necessary antibiotics should always be completed to ensure adequate treatment and to prevent bacterial resistance.”

How do I know if I need antibiotics?

“There are times when individuals have a mild self-limiting illness that may even be viral – but think they need an antibiotic,” says Faye. Check with your GP or a pharmacist first.

Are some antibiotics riskier than others?

Yes. “Every antibiotic has the potential to attack both beneficial and detrimental bacteria, thus disrupting the gut microbiota temporarily or permanently,” says Faye. “However, our research suggests that a narrow-spectrum antibiotic – one that targets specific bacteria – may be associated with a lower risk of developing IBD. We saw that nitrofurantoin, an antibiotic commonly used to treat UTIs, and which has minimal impact on the intestinal microbiome, did not appear to increase the risk of developing IBD.”

The classes of antibiotics with the highest risk were nitroimidazoles, of which the most commonly prescribed is metronidazole.

Could probiotics mitigate my risk?

“There is not enough evidence to show how they might help in people at risk of developing the disease, or even for those who have already been diagnosed,” says Sarah Sleet, CEO of the charity Crohn’s & Colitis UK. However, Dr Elisa Marroquín, assistant professor at Texas Christian University in the US, last year co-authored a study showing that taking probiotics – which usually come in capsules – could prevent or lessen some antibiotic-induced changes to the gut microbiome.

“When participants take antibiotics, we see several consistent changes in some bacterial species,” she says. “But when treatment was combined with probiotics, the majority of those changes were less pronounced and some changes were completely prevented.”

Probiotics can also help protect species diversity and even restore the populations of some friendly bacteria such as Faecalibacterium prausnitzii, which reduces inflammation and promotes a healthy intestinal barrier.

Should I take probiotics alongside antibiotics, or after the course has finished?

Dr Marroquin says: “According to our review, probiotics should be consumed alongside antibiotics to prevent or decrease side effects such as antibiotic-induced diarrhoea.

“Taking probiotics and antibiotics simultaneously also seems to decrease the risk of developing antibiotic-resistant bacteria in our gut. In addition, we also found that combining antibiotics with probiotics appears to help preserve the composition of the gut microbiota, however, more research is needed in this area.”

Are some probiotic strains better than others?

Probably, but we don’t know for sure. There are “next-generation probiotics” that seem to be very beneficial, likely more than the common probiotics that are currently available in the market, but we are still in early phases of research.

How do I pick an effective probiotic treatment?

Dr Marroquin says: “Try to pick a probiotic that contains at least eight different bacterial species. This can slightly help to preserve the diversity in our gut. One of the markers that keeps appearing as an indicator of a healthy gut microbiota is having high diversity.”

Can eating a certain diet reduce the risk of IBD?

Professor Tim Spector is the scientific co-founder of the nutrition app Zoe and an expert on the microbiome. He’s an advocate of fermented, colourful and fibre-rich foods that feed our bugs, known as prebiotics. “It’s a good idea to eat fermented foods daily and make sure we continue eating diverse plant fibres to support our gut microbiome during antibiotic treatment,” he says. All food for thought.