According to the hygiene hypothesis, early life infections are essential to prime the immune system and so prevent allergic and auto-immune conditions later in life.
In line with this hypothesis, several studies have looked at the role of bacteria and other infectious agents in triggering diseases like MS.
Helicobacter pylori is a type of bacteria that can infect the lining of the stomach and the upper part of the intestine. Infection with helicobacter pylori is the cause of most stomach and duodenal ulcers.
In recent years a relationship between helicobacter pylori and many disease conditions has been reported. However studies of its relationship with MS have produced contradictory results.
Researchers from Australia and the Netherlands recently looked again at this relationship. They worked with 550 people with MS, who were age- and gender-matched to 299 healthy controls.
In this study, helicobacter pylori infection was associated with a slight (in terms of impact) but statistically significant reduction of risk in women.
This could show that helicobacter pylori helps protect against the development of MS. However, the fact that the association was seen almost exclusively in women requires further investigation, as there may be other factors can explain the association.