New evidence indicates multiple sclerosis is triggered by normal, so-called "good" bacteria found in the intestines, according to a study recently published in the journal Nature.

The human gut plays host to some 100 billion bacteria from 2,000 different species, scientists say. They help us digest food and, according to recent findings, also play a role in promoting autoimmune diseases such as MS, say researchers at the Max Planck Institute of Neurobiology in Munich, Germany.

In their research, mice genetically predisposed to MS that had their normal gut bacteria removed and they remained healthy. Meanwhile, those that kept their gut bacteria developed MS-like symptoms.

Still, it's not clear which of the hundreds of species of bacteria may be responsible for the disease and researchers are just beginning to narrow down the possible culprits.

"I don't personally believe that one type of bacteria" is to blame, says Gurumoorthy Krishnamoorthy of the Max Planck Institute.

If the MS-bacteria is isolated, it may be possible to develop an antibiotic treatment for the disease, which afflicts about 2.1 million worldwide.