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Antacid use dramatically reduces healthy gut microbial flora

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11 December 2015

Groningen, the Netherlands – The most commonly used antacids, proton-pump inhibitors, can dramatically change the composition of the gut flora. This is the conclusion of researchers from the Netherlands in a publication appearing today in the scientific journal Gut. 'Our results explain why people who regularly take these antacids are more prone to develop intestinal infections caused by bacteria such as Salmonella and Clostridium difficile,' says Floris Imhann, first author of the article.

Proton-pump inhibitors (PPIs) are among the top-10 most commonly used drugs worldwide. PPIs inhibit the production of gastric acid in the stomach, and are used to treat heartburn and prevent gastric ulcers. However, previous studies looking into medical records had found an increase in intestinal infections among PPI users.

Researchers from the University Medical Center Groningen and Maastricht University Medical Center asked 1,815 study participants to collect and freeze their stool. The bacterial communities in these stool samples were then studied in the laboratory using microbial DNA-sequencing techniques. The results were clear: approximately 20 % of gut flora was altered in the group using PPIs – a substantial change. 'Some groups of bacteria were present in much larger numbers, while the numbers of other groups were clearly reduced.' Imhann also examined the bacterial composition in the some participants' saliva. 'Antacids make gastric acid slightly less acid. Normally bacteria should be killed by gastric acid, but we found more mouth bacteria present in the gut of PPI users,' says Alexandra Zhernakova,  one of the principal investigators of the study.

The changes in the composition of gut flora explain why the use of antacids increases the risk of intestinal infection. 'When some beneficial bacteria nearly disappear from the gut, there is an opportunity for pathogenic bacteria to grow. This is especially true of the Clostridium difficile, a bacterium that can be dangerous for vulnerable patients.'

These are startling results. 'We have known for some time that drugs such as antibiotics influence gut flora. Our study shows that the use of PPIs also seriously impacts the composition of intestinal bacteria.' There is, however, no reason to panic, emphasizes Professor Rinse Weersma, gastroenterologist and one of the principal investigators. 'For some patients, antacids are absolutely necessary.' What these results show is that antacids must be used with care. 'Earlier research has shown that approximately half the people using proton-pump inhibitors no longer actually need to take them.' Weersma and Imhann therefore advise physicians should be aware of the side-effects and help their patients to avoid unnecessary use of PPIs.​