There's a 'double-edged sword' in your stomach

Scientists are studying the bug linked to stomach ulcers for means to fight Alzheimer's disease.

- F.D. Flam

It's not always obvious which of the multitude of species of bacteria riding around in us should be classified as germs and attacked, and which are essential workers that should be nurtured.

One that's particularly hard to classify is H. pylori, which was the subject of the 2005 Nobel Prize for the discovery that it causes peptic ulcers.

But more recent studies have connected it with benefits, including lowering the risk of oesophageal cancer. In a paper published in Science Advances, researchers in Sweden described how the bacteria can inhibit the formation of amyloid deposits, which are found in the brains of individuals with Alzheimer's and Parkinson's disease.

Scientists are just beginning to understand the microbes that have been with us for millennia – the so-called microbiome, which is being drastically depleted as an unintended consequence of antibiotic use, dietary changes and other aspects of modern life.

Until the start of the 20th century, we all carried H. pylori. Now, it's headed for global extinction. But before it disappears, it's worth understanding what it does and why we all once carried it.

While many doctors are happy to say good riddance to H. pylori – which also has been associated with stomach cancer – scientists are discovering more positive benefits, including a few studies that have shown it might also lower the risk of asthma and allergies, and help protect against obesity and Type 2 diabetes.

As I've written previously, this stomach bug is a feature of our biology, not just a problem that needs to be eliminated.