The gut microbiome, which consists of a complex community of bacteria, fungi, and yeasts, plays a vital role in maintaining human health. Recent research has highlighted how disruptions to this microbiome are associated with a variety of chronic health conditions. Traditionally, it has been understood that antibiotics can negatively affect the gut microbiome by eliminating both harmful and beneficial bacteria. However, a new study has revealed that other classes of prescription medications also pose risks to the microbiome, with lasting effects that can persist for years after discontinuation.
A recent study published in the American Society for Microbiology’s Journal mSystems has shown that numerous prescription medications, including antidepressants, beta-blockers, stomach acid reducers, and anti-anxiety drugs, can adversely affect the gut microbiome even after the medications are stopped. The findings suggest that the repercussions of these drugs on gut health can linger for several years.
Dr. Babak Firoozi, a board-certified gastroenterologist at MemorialCare Orange Coast Medical Center, expressed cautious optimism about the study. He stated, “The methodology was robust, and convincingly linked changes in the gut microbiome to medication uses, but this was not a controlled trial. There are numerous variables that cannot be accounted for, such as environmental factors, diet, and geographic location.” He emphasized the surprise at the number of drug classes that appeared to influence the gut microbiome.
The researchers analyzed data from 2,509 adults enrolled in the Estonian microbiome cohort, part of the Estonian biobank—a population-based databank of volunteers. Participants, aged between 23 and 89 years, provided samples of blood, cheek swabs, and stool. Using shotgun metagenomics sequencing, the researchers scrutinized the composition of the gut microbiomes. A subset of 328 individuals provided a second stool sample after a median follow-up of 4.4 years, allowing for a deeper analysis of microbiome changes over time.
Participants’ prescription drug usage was meticulously tracked via electronic health records. At the time of the initial sample, participants were on 433 different prescription medications and had used a total of 507 different drugs within the preceding five years. Notably, over one-third of participants were not taking any medications at the time of the first sample, while those on medications averaged three different types.
From the analysis of 186 different drugs, the researchers found that 167 impacted the microbiome to some extent, with 78 demonstrating long-term effects on its composition. Significant changes were observed in individuals who had taken:
Antibiotics - medications that combat bacterial infections by killing or inhibiting bacteria. Antidepressants - drugs that boost neurotransmitter levels in the brain to alleviate depression. Antipsychotics - medications used to manage psychosis linked to conditions like schizophrenia and bipolar disorder. Beta-blockers - drugs that address cardiovascular issues, including angina and hypertension. Biguanides - such as metformin, prescribed for type 2 diabetes. Proton Pump Inhibitors (PPIs) - used to reduce stomach acid for treating acid reflux and ulcers. Benzodiazepines - commonly prescribed for anxiety and sleep disorders.The study revealed that prolonged medication use and polypharmacy (the use of multiple medications) increased the negative impact on the microbiome. Notably, benzodiazepines showed the most significant adverse effects.
The authors of the study caution that since many medications are taken continuously over a lifetime, rather than for short durations like antibiotics, their physiological effects on the microbiome can be profound. Dr. Elin Οrg, co-author and head of the Microbiome Research Group at the University of Tartu, stated, “Our findings highlight that even past drug use can leave a lasting imprint. We also discovered that within the same class of drugs, individual medications can have very different impacts on the microbiome.”
For instance, when comparing benzodiazepines, alprazolam (Xanax) was found to have a much broader effect on the microbiome than diazepam (Valium). This variance could inform future therapeutic decisions and warrants further investigation.
Since the early 1900s, the significance of the gut microbiome has become increasingly clear. The approximately 100 trillion microorganisms residing in the gut are crucial for overall health. A balanced microbiome, characterized by high diversity and richness, supports the well-being of its human host. Disruptions, or dysbiosis, in the microbiome have been linked to numerous health issues, including inflammatory bowel disease (IBD), obesity, allergic disorders, diabetes, cardiovascular disease, and autoimmune conditions.
While antibiotics are known to indiscriminately eliminate beneficial gut bacteria, other medications impact the microbiome in different ways. For example, Dr. Firoozi noted that some medications, like antidepressants and beta-blockers, may alter intestinal motility, consequently affecting gut bacteria by slowing down the transit through the digestive tract. Proton pump inhibitors have also been shown to influence the microbiome by reducing gastric acid, a key defense against bacterial overgrowth.
Dr. Firoozi also suggested that benzodiazepines might alter dietary habits, which are closely tied to the health of the gut microbiome. Understanding the complex interactions between medications and gut health is essential for healthcare professionals and patients alike, emphasizing the importance of personalized medicine in prescribing practices.
