I keep reading that Helicobactor pylori causes ulcers. That’s supposed to be an improvement on the old idea that it might be stress, or diet, or some unknown factor that leads to the condition.
But it’s actually not correct. The idea that the bacerium causes ulcers is way too simplistic, as so many science “facts” spread by pop science articles are.
Now, it’s true that most people who have ulcers harbor H. pylori in their stomachs. But it’s also true that most people who harbor H. pylori in said guts do not have ulcers.
Here’s a bit more detail [emphasis mine]:
[H. pylori] was identified in 1982 by Barry Marshall and Robin Warren, who found that it was present in patients with chronic gastritis and gastric ulcers, conditions that were not previously believed to have a microbial cause. It is also linked to the development of duodenal ulcers and stomach cancer. However, over 80 percent of individuals infected with the bacterium are asymptomatic and it has been postulated that it may play an important role in the natural stomach ecology…More than 50% of the world’s population harbor H. pylori in their upper gastrointestinal tract.
And this fact sheet adds that “H. pylori causes more than half of peptic ulcers worldwide.” “More than half” is far from “all.”
So, plenty of people have ulcers but no H. pylori, and plenty of people have H. pylori but no ulcers. Instead of saying that the bacterium causes ulcers, it would be more accurate to say that H. pylori has a strong association with ulcers and that infection with it somewhat increases a person’s chance of having ulcers.
This may not be the most burning (pun intended) question of the day, but it’s been bugging me (same) for a long time.