Medicines are important as they help treat infections, pain, heart conditions, anxiety, depression and digestive problems. However, a new study suggests that their effects may extend beyond the condition they are prescribed for. Researchers have found that several commonly used medicines can leave long-lasting changes in the gut microbiome. These changes were not seen only with antibiotics, which are already known to impact gut bacteria.

Antidepressants, beta-blockers, acid-reducing medicines and benzodiazepines were also seen causing significant microbial changes. In some cases, these "fingerprints" could still be detected years after people had stopped taking the medicines. The findings are important because the gut microbiome is involved in digestion, metabolism and immune activity, and differences in its composition have been linked with several aspects of health. The study, led by researchers from the University of Tartu Institute of Genomics, looked at stool samples and prescription records from more than 2,500 people. The researchers wanted to understand whether medicines taken in the past could still influence the microbes found in a person's gut when a sample was collected later.

What Is The Gut Microbiome?

The gut microbiome refers to the huge community of microorganisms that live mainly in the digestive tract. It includes bacteria as well as other microorganisms, and its composition differs from person to person. These microbes help break down certain components of food and are involved in processes related to metabolism, digestion and the immune system. The balance between different types of microbes can be influenced by diet, lifestyle, illness and medicines.

Due to this, researchers are increasingly studying the microbiome to understand how different factors may affect health. The new study suggests that medication history could be another important factor shaping the gut microbiome.

Antibiotics Were Not The Only Medicines Involved

Antibiotics are well known for affecting gut bacteria because they are designed to kill or stop the growth of bacteria. However, the study found that their effects were only part of the picture. Researchers identified a lasting link between several other groups of medicines. These includes:

  • Antidepressants: Certain selective serotonin reuptake inhibitors (SSRIs) were linked to long-term changes in the gut microbiome.
  • Beta-blockers: These medicines are commonly used for conditions such as high blood pressure and some heart problems and were associated with differences in gut bacteria.
  • Proton pump inhibitors (PPIs): These acid-reducing medicines are widely used for acid reflux and related digestive conditions and showed persistent microbial effects.
  • Benzodiazepines: Commonly prescribed for anxiety and other conditions, these medicines showed surprisingly strong associations with changes in gut microbes.
  • Antibiotics: Several antibiotics, including penicillin combinations and macrolides, were associated with lasting microbial changes.

Benzodiazepines Showed A Surprising Effect

One of the more notable findings involved benzodiazepines. The researchers found that their association with changes in the gut microbiome was comparable to that seen with broad-spectrum antibiotics.

The study also showed that medicines belonging to the same drug class do not necessarily have identical effects. For example, different benzodiazepines, including diazepam and alprazolam, differed in how strongly they were associated with changes in gut microbes. This means researchers may need to look at individual medicines rather than assuming that all drugs within the same category affect the microbiome in the same way.

The Effects Could Stay For Years

The researchers were particularly interested in whether microbial changes disappeared after a person stopped taking a medicine. Their findings suggest that this does not always happen quickly. For a lot of medicines, differences in the microbiome could still be detected years after the medication had been stopped. A smaller follow-up group also provided evidence that starting or stopping certain medicines was followed by predictable changes in gut microbes.

The follow-up analysis confirmed persistent effects associated with PPIs, SSRIs and some antibiotics. While the follow-up group was smaller, these findings added support to the idea that at least some medication-related microbial changes may be long-lasting.

These findings could change how scientists interpret microbiome studies. If someone has a particular pattern of gut bacteria, researchers may connect it with their current health condition, diet or lifestyle. But an older prescription could also be contributing to that pattern.

Dr Oliver Aasmets, lead author, said, "Most microbiome studies only consider current medications, but our results show that past drug use can be just as important as it is a surprisingly strong factor in explaining individual microbiome differences."

The study does not mean that people should stop taking prescribed medicines because of their possible effects on gut bacteria. Medicines are often necessary and provide important health benefits. Instead, the findings highlight the need for doctors and researchers to consider a person's medication history when assessing the gut microbiome.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.