Pharmaceutical drugs harm your gut biome

The four most harmful drug categories

Results / outcomes

References

A study published in October 2019 (1) found that the gut microbiome is at high risk of damage from pharmaceutical drugs in eighteen commonly used drug groups. This study shows that pharmaceutical drugs are even more harmful to the biome than earlier research indicated.

The term "gut microbiome" refers to the whole of the microbial population in the gut. The gut biome is an essential and health-giving "organ" in the human body. It comprises 40 trillion bacteria, viruses and fungi, with the bacteria belonging to over two thousand species in a healthy individual.

The composition of the gut bacteria is different between different individuals and population groups, conspicuously affected by food patterns, excessive hygiene and by medications (especially antibiotics).

In the last two decades several studies have shown that the health of the gut microbiome directly affects numerous chronic modern degenerative diseases such as obesity, diabetes, liver disease, cancer, depression, dementia, autism, and other neurological disorders.

The harmful effects of pharmaceutical drug use range from changes in the relative proportions of different beneficial and potentially harmful bacterial species to alterations in genes and the cellular metabolism of the bacteria themselves.

The outcomes measured by the study included harmful intestinal infections and microbiome-linked conditions such as the risk of obesity and depression. It also found that pharmaceutical drugs in another eight categories promoted antibiotic resistance.

The researchers examined the effects of using drugs from forty one pharmaceutical categories on three groups of people: a control group representative of the general population; a group with inflammatory bowel disease (IBD) and a third group containing individuals with IBD as well as healthy controls. They compared 1,880 faecal samples from the three groups, analysing differences in the composition of the gut microbiota and the bacteria cellular metabolism induced by the drugs. They looked at the effects of using a single drug, and of multiple drugs used together.

The four most harmful drug categories

The study identified four drug categories that had the greatest impact on the gut microbiome:

• Antibiotics are used by more than one in three Europeans every year. Antibiotics wreck the gut biome, often for life.
• Proton pump inhibitors (PPIs). PPIs are used to treat digestive disorders such as heartburn, flatulence, oesophageal metaplasia and gastroesophageal reflux, which affect between 11% and 24% of the European population. PPIs are also used to treat peptic ulcers which occur after an overgrowth of Helicobacter pylori in the stomach lining. The study found that PPI users had increased numbers of bacteria in the upper digestive tract because of the reduced acidity, as well as increased levels of fatty acid synthesis within the gut lumen.
• Laxatives are used to relieve or prevent constipation, from which 17% of European adults suffer.
• Metformin is used to treat type 2 diabetes, from which 10% of the adult European population suffer. This drug category causes an increase in the level of the bacterium Escherichia coli, leading to harmful pathogenic infection.

Results / outcomes

The researchers also found that another seven drug groups caused significant changes to the gut bacterial populations. For example, a class of antidepressant called selective serotonin reuptake inhibitor (SSRIs) caused a spike in the potentially pathological bacterial species Eubacterium ramulus. Another example: oral steroids caused an abundance of methane-producing bacteria, promoting overweight / obesity / a high body mass index.

The researchers found that the efficiency and toxicity of pharmaceutical drugs are influenced by the patient's gut biome, as well as affecting it. The interaction between different drugs and the gut biome is also significant and complex. With each patient having their own individualised cocktail of drugs and medications, and their own and unique gut biome, the prescription of drugs for a particular patient by their doctor is virtually done in the dark. According to the lead researcher, "this study highlights the importance of considering the role of the gut microbiota when designing treatments and also points to new hypotheses that could explain certain side-effects associated with medication use."

References

1. Vich Vila, Arnau. et al. Impact of 41 commonly used drugs on the composition, metabolic function and resistome of the gut microbiome. Presentation at UEG Week, Barcelona, October, 2019.