What Causes an Ulcer?

For almost 100 years, doctors believed that stress, spicy foods, and alcohol caused most

ulcers. Now we know that most peptic ulcers are caused by a particular bacterial infection in

the stomach and upper intestine, by certain medications, or by smoking.

In 1982, two doctors — Barry Marshall and Robin Warren — discovered a certain kind of

bacteria that can live and grow in the stomach. Both doctors went on to win the Nobel Prize

for their discovery. The medical name for these bacteria is Helicobacter pylori (or H.

pylori, for short). Today doctors know that most peptic ulcers are caused by an infection

from H. pylori.

Experts believe that 90% of all people with ulcers are infected with H. pylori. But strangely

enough, most people infected with H. pylori don't develop an ulcer. Doctors aren't completely

sure why, but think it may partly depend upon the individual person — for example, those who

develop ulcers may already have a problem with the lining of their stomachs.

It's also thought that some people may naturally secrete more stomach acid than others — and

it doesn't matter what stresses they're exposed to or what foods they eat. Peptic ulcers may

have something to do with the combination of H. pylori infection and the level of acid in the

stomach.