The bacteria causing stomach ulcers...and why you might want to keep them

Kate MacDonald
17 December 2018

Above: A teenager has a stomachache. Image © metamorworks,

Imagine these symptoms: A pain in your stomach that makes you not want to eat. Constant nausea, vomiting, bloating, and heartburn. Getting tired easily, and losing weight quickly. These are all symptoms of a stomach ulcer, a painful sore on the lining of the stomach.

Sounds unpleasant, right? Many people want to avoid these symptoms at all costs. But what if you had to choose between these symptoms - and those of asthma? Let’s learn about the connection between these two illnesses.

Did you know? Adults between 30 and 50 years old are most likely to get ulcers.

Dr. Marshall’s discovery

Given the pain an ulcer can cause, most people want to avoid developing an ulcer. But back in 1984, an Australian scientist named Dr. Barry Marshall did just the opposite. He purposely  drank a broth containing a corkscrew-shaped bacterium called Helicobactor pylori. He was trying to give himself a stomach ulcer!

This is not the way that most scientists do their work! Researchers generally perform carefully thought-out experiments in the controlled environment of their laboratories. No scientist would encourage drinking any chemical you found lying around in a lab. But Dr. Marshall had a point to prove.

Before the 1980s, every doctor in the world was sure that stomach ulcers were caused by stress. Every doctor, that is, except Barry Marshall. Dr. Marshall had been trying for years to convince his colleagues that ulcers were actually the result of the stomach being colonized by H. pylori, a species of spiral-shaped bacteria. But no one believed him. He tried performing experiments with bacterial cultures and laboratory animals, but his evidence just wasn’t strong enough.

When Dr. Marshall drank broth containing a culture of H. pylori, this rogue experiment caused massive inflammation in the lining of his stomach. Finally, there was support for a direct relationship between this squiggly bacteria and diseases of the stomach. Finally, the world was listening!

Years of further research confirmed what Dr. Marshall had been saying all along: The bacterium H. pylori causes stomach ulcers. Before this discovery, doctors used to recommend bed rest and bland foods as treatments for ulcers. After this discovery, doctors could prescribe antibiotics to treat ulcers. This was revolutionary, and soon doctors began using a new mantra: “The only good H. pylori is a dead H. pylori”.

Doctors began to take a “search-and-destroy” approach to H. pylori, getting rid of it in every patient they came across - even the ones who didn’t yet have a stomach ulcer! These doctors were very successful. Rates of stomach ulcers around the world have dropped dramatically since then, especially in developing countries.

Did you know? H. pylori is also involved in stomach cancers. As the rate of stomach ulcers dropped around the world, so did the rate of stomach cancers.

H. pylori: Friend and foe

At the same time, and at almost the same rate, more and more people around the world were getting asthma. As scientists would soon learn, there was a connection between lower rates of stomach ulcers and higher rates of asthma.

At first, this may appear to be just a coincidence. Most of us know several people with asthma and few with stomach ulcers. But we also know lots of people with Netflix subscriptions and few who buy VHS tapes. Does this correlation mean that watching Netflix is responsible for higher rates of asthma, especially among young people? Of course not!

In this case, however, there actually is a link between stomach ulcers and asthma. You guessed it - that link is H. pylori.

In 2004, scientists at New York University showed that if you carry H. pylori in your stomach, you are 30% less likely to become asthmatic. In other words, the same bacterium which is known to increase your risk of stomach ulcers is actually protecting you from asthma!

H. pylori is both a good guy and a villain, depending on the circumstances. When the same organism makes you sick and keeps you healthy, that’s a process called amphibiosis. H. pylori is one example of an amphibiotic organism, but there are many others.

The role of antibiotics

Antibiotics are our most important and useful agents in the fight against bacterial infections. They allow us to prevent and cure disease. But most antibiotics will kill any bacteria they come across, not just the one responsible for your illness. They will destroy bacteria which may be playing a protective role – bacteria like H. pylori.

The discovery of antibiotics, such as penicillin, was a huge step for humankind. Antibiotics have saved countless lives. However, over the past thirty years, they have come to be over-prescribed by doctors.

Further, antibiotics are regularly given to farm animals to help them gain weight. With the over-prescription of antibiotics in people, and the unnecessary use of antibiotics in livestock and agriculture, opportunities for antibiotic-resistant strains of microorganisms to emerge are easily found.

It’s not just asthma...

Asthma, diabetes, hay fever, food allergies, celiac disease. Almost everyone today knows at least one person suffering from these chronic illnesses. And there have been more and more cases of these illnesses over the past three decades.

Current research presents a very strong case that it is the overuse of antibiotics, especially in the Western world, that is responsible for these numbers going up (4). Doctors and researchers are attempting to combat these illnesses using the microbiome. An affected person may be missing some “protective” bugs, and new treatments aim to restore them. For example, there is a nasty gastrointestinal illness called Clostridium difficile infection (or simply “C. diff.”). This is caused by an imbalance in the microbial species inhabiting your intestinal tract. To treat this, doctors might transplant fecal matter (poop) from a healthy donor into the person being treated. It’s gross, but it works!

The many microbes that colonize most of the available surfaces of your body, inside and out, are called your microbiome. All of the organisms in your microbiome are there for a reason, and they all have a part to play. Many are absolutely essential for your human body to function properly. Eliminating an entire species from your microbiome is generally a bad strategy. We would never suggest removing an entire species of tree from the rainforest. In fact, conservationists work very hard to ensure that the rainforest ecosystem stays diverse. Your microbiome is an ecosystem, just like a rainforest, and should be treated just as delicately!

Did you know? Your risk of asthma, diabetes, and food allergies is heavily influenced by the kinds of microorgansims living inside your body.

The microbes that call your body home can sometimes have more influence over your health than your own human genes. This is why it’s so important to understand them, and to take good care of them. Recognizing the part your microbiome plays in keeping you healthy, and taking antibiotics only when necessary, are excellent places to start.

Learn more

About the microbiome (2018)
Kavil Foundation

How bacteria rule over your body (2017)
Kurzgesagt - In a nutshell

Is your gut microbiome the key to your health and happiness? (2017)
The Guardian

Kate MacDonald

I am a third year student at the University of British Columbia (UBC) in Vancouver, working toward a degree in cell and developmental biology. Early in my second year, volunteering in a genetics lab sparked my passion for research, and I was driven to explore a career in cellular biology. I am beginning work on my undergraduate thesis, and I plan to pursue an MSc after I graduate. Outside of the lab, I am enthusiastic about science outreach, writing and volunteering for Let’s Talk Science. I also host a series of biodiversity-themed YouTube videos for the Beaty Biodiversity Museum at UBC.

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