The Hygeine Hypothesis: Hot Debate

The Hygiene Hypothesis proposes that you need to have certain infections to have a healthy immune system. If you are not infected with various common germs, your immunity does not have the chance to practice killing germs and learning the difference between invading organisms and your own cells. For example, does Helicobacter pylori, the bacteria that causes stomach ulcers, also prevent diseases such as eczema? Nobody knows. Being infected with Helicobacter is associated with decreased risk for eczema (Journal of Epidemiology & Community Health, July 2007), but it is also associated with an increased risk for asthma (Gut, May 22, 2008).

Your immunity protects you from certain infections by searching out and killing foreign germs in your body. It does this by attacking surface proteins on invading bacteria and viruses. However, your immunity is not supposed to attack your own cells, so it does not attack cells that have the same surface proteins that your cells have. It may attack your lungs and cause asthma instead of attacking the bacteria that causes stomach ulcers. Your immunity may get so active with Helicobacter infections that it may attack your own skin to cause eczema.

The Hygiene Hypothesis has not been proven. It is just a hotly debated theory among doctors; only time will sort out the conflict and tell us if Helicobacter stomach infections help your immunity protect you from other infections. More on Helicobacter pylori