Margit Koudelka

The effect of medication on the gut flora

Medication influences the microbiome in an unexpected and severe way. Yet conversely, gut bacteria determine the effectiveness of medicines. This interaction is currently at the forefront of scientific interest.

Univ.-Prof. Dr. Vanessa Stadlbauer-Köllner

Assoz. Vanessa Stadlbauer-Köllner*

A disturbed harmony

A great number of different bacteria and other microorganisms bustle about in our intestines and form our so-called microbiome. A balanced composition of these tiny „helpers“ can literally give us a good gut feeling. Our intestinal flora plays a central role in different processes throughout our entire body and is responsible for our health. We have known for quite some time now that different medicines, such as antibiotics and some pain-killers, can irritate the gastric and intestinal mucosa, and massively change the composition of our microbiome. For this reason, these drugs were combined with proton-pump-inhibitors for many years to protect the stomach. By we know, however, that these drugs can also damage the intestinal flora.

The pill, antihypertensives and cholesterol-reducing drugs

Many other medicines can also affect the composition and function of the microbiome. The list is long: Contraceptive pills and other hormone products, antihistamines, antihypertensives, antidiabetics, cholesterol-lowering drugs, cortisone and antidepressants all play a part. These are all medicines that are frequently prescribed and ingested. A recent study estimates that at least 25% of all medicines have a significant impact on our intestinal microbiome. „Drugs don’t only affect the growth and function of the bacteria but also the intestinal barrier, the intestinal motility (in other words, the muscle movement of the intestines) and the intestinal immune system. Whether this is good or bad for patients remains to be seen and needs to be studied on a case-by-case basis“, explains Assoc. Prof. Priv.-Doz. Dr Vanessa Stadlbauer-Köllner, a specialist in the clinical department for Gastroenterology and Hepatology at the Medical University Graz, in an interview with „bauchgefühl“.

Darmflora und Medikamente

Lack of resistance

We have known for a long time that antibiotics reduce the biodiversity of our microbiome, that is a reduction in the number of different species. This can lead to the microbiome losing its durability. Furthermore, harmful factors can also unbalance our microbiome. „As a result, pathogenic – or harmful – germs can easily inhabit and propagate in the intestines. Ultimately this leads to a damaged intestinal barrier where bacterial products can enter our bloodstream and cause inflammations throughout our bodies“, clarifies the expert. There isn’t sufficient scientific data that determines to what extent we can counteract the imbalance of the microbiome via our diet during or after the intake of medicines.

Nevertheless: „Our diet is basically the most important determinant of our intestinal microbiome composition and as such, a diverse diet contributes to the plethora of the intestinal microbiome“, clarifies Stadlbauer-Köllner.

A focal point in science

Furthermore, scientists are studying to what extent they can keep the unpleasant side effects of drugs on the microbiome in check with the targeted intake of probiotics. „There is already good scientific data concerning the prevention of antibiotic-associated diarrhoea. Further research is needed regarding other medicines. We are currently conducting a study at the Medical University Graz in which we are trying to prevent the negative effects of proton-pump-inhibitors in the intestinal microbiome with the help of probiotics“, relates the scientist.

Contrarily, we can also come to the following conclusion: If medicines can influence the intestinal flora, then the ingested probiotics should also have an effect on the efficacy of medicines. Our expert explains: „There is no general answer to this question. Gut bacteria can also influence the efficacy of medicines since they metabolise them. The composition of the intestinal flora can determine the efficacy and side effects of some drugs. What role probiotic bacteria can play in all of this remains the subject of further scientific studies“: Studying the combined use of probiotics and different drugs and determining the impact that microorganisms have on the effects and side-effects of medicines may be an exciting field of research in the future.

Higher risk of infection

By now we have established that a reduced biodiversity can have a negative impact on the disease or symptoms against which a patient is taking drugs. „A reduced microbiome diversity can lead, for example, to an overgrowth of dangerous germs. A good example is a Clostridium dificile infection that can occur during or after antibiotic treatment and is often very dangerous. These differences are less clear-cut with other medicines, and much more work is needed to understand the interactions between the microbiome, medicines and diseases“, describes Stadlbauer-Köllner.

Afterwards is too late

The doctor definitely recommends doing the intestines some good with probiotics after the added stress of drug treatment. One should ideally start the intake of probiotics on the first day of an antibiotic treatment, at the latest after 2 days. „By doing so, the risk of a Clostridium dificile infection can be reduced by 60%. However, it is too late after a completed antibiotic intake! This was proven by a paper in the professional journal “Cell” at the beginning of September 2018. If the probiotic prophylaxis is only taken after antibiotic treatment, the regeneration of the intestinal microbiome isn’t accelerated and possibly even slowed down. A large meta-analysis conducted last year by the renowned Cochrane-Group showed that probiotics are effective in preventing a Clostridium dificile infection during the intake of antibiotics. A further analysis from New York revealed that the clinical effect of probiotics is strongest when taken no later than 2 days after the first antibiotic intake“, explains the expert.

Although, not every probiotic is the same: It is difficult to determine which of the currently available probiotic products works best. There are, however, a few quality criteria that you should keep an eye out for: „It definitely makes more sense choosing a product that contains several species in a high concentration and whose efficacy has been proven“, recommends the doctor. Furthermore, one shouldn’t take the antibiotic and probiotic at the same time. Instead, take them at different times so that the probiotic bacteria aren’t immediately destroyed by the antibiotic. Your local pharmacy can definitely give you some good advice about which probiotic to choose.

*Assoz. Vanessa Stadlbauer-Köllner, Fachärztin an der Klinischen Abteilung für Gastroenterologie und Hepatologie an der Medizinischen Universität Graz.

What are probiotics?

Darmflora und Medikamente

Probiotics are „good“ microorganisms, mostly bacteria, that have a wholesome effect on our intestines. These include, among others, bifidobacteria and lactic acid bacteria. These bacteria can help destroy harmful microorganisms. They also produce important substances such as vitamin K and butyric acid and influence the intestinal immune system as well as the intestinal barrier. The helpful intestinal bacteria must be resistant against the gastric acid of the stomach in order to reach the intestines.  They usually don’t permanently colonise the intestines and influence our organism as long as they are ingested regularly. However, it has been proven that some probiotic bacteria permanently called the intestines their home. Such helpful probiotic bacteria – specifically combined – can be found in pharmacies for many different areas of application. These probiotics follow strict government regulations in which the bacterial count (the number of contained bacteria) and the composition of the different bacterial strains should be constant.

These helpful bacteria are also naturally found in many food products such as kefir, plain yoghurt, buttermilk, curd cheese, cheese, sauerkraut, kimchi (pickled cabbage), apple vinegar, miso (a paste made up of soybeans, different types of grain and salt) and yeast.

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