Inside the stomachs of half the world's population, bacteria that look like small octopuses burrow into the lining, attach themselves, and multiply like crazy. These bacteria, called Helicobacter pylori or H. pylori for short, can cause ulcers, gastritis, and even cancer. But, as virulent as the bacteria can be, most people have little or no symptoms of infection. A group of researchers from Japan wondered if that meant that the body produces chemicals that can fight off H. pylori.

What the researchers wanted to know: Does the body produce a natural defense mechanism against H. pylori bacteria?

What they did: Previous studies have shown that H. pylori bacteria settle into only the upper layers of the stomach and don't do well deeper down in the lining. In this study, the researchers cultured H. pylori cells in a laboratory, and then added carbohydrate molecules called O-glycans only found deeper in the stomach tissue.

What they found: In larger quantities, the O-glycans nearly stopped the growth of H. pylori. At lower concentrations, the O-glycans did not affect growth but distorted the shape of the bacteria and inhibited its movement, making it ineffective. Effectively, the body seems to be producing a natural antibiotic, and the scientists say this is the first time that this kind of molecule has been shown to be able to fight off an infection.

What it means to you: Because the researchers have found a way that the body can kill, or at least tame, H. pylori bacteria without treatment, their study gives hope to the millions of people whose bodies are affected by it. Don't race down to your local pharmacy tomorrow, but this article may lead to the development of new medicines to treat infections caused by H. pylori.

Caveats: The scientists still don't know why some people have symptoms from H. pylori while others are fine, and treatment is still a long, long way off.

Find out more: The National Institutes of Health has a page on H. pylori and gastrointestinal diseases, including peptic ulcers, the most common side effect of H. pylori infection.

Read the article: Kawakubo, M., Ito, Y., Okimura, Y., Kobayahsi, M., Sakura, K., Kasama, S., Fukuda, M.N., Fukuda, M., Katsuyama, T., and J. Nakayama. "Natural Antibiotic Function of aHuman Gastric Mucin Against Helicobacter Pylori Infection." Science. Aug. 13, 2004, Vol. 305, No. TK, pp. 1003-1006.

Abstract online: http://www.sciencemag.org