A type of bacteria that commonly infects infants is responsible for causing stomach ulcers in adults. Now researchers are learning that this same bug may keep women from getting MS.

Australian researchers have discovered that a type of bacteria called Helicobacter pylori (H. pylori), which causes stomach ulcers, may also protect women from developing multiple sclerosis (MS). Women with MS were found to have fewer immune system cells called antibodies in their blood designed to fight H. pylori. This suggests a possible link between too few H. pylori bacteria and the development of MS.

Professor Allan G. Kermode of the Centre for Neuromuscular and Neurological Disorders at the Western Australian Neuroscience Research Institute and colleagues recently published their results in the Journal of Neurology, Neurosurgery, and Psychiatry.

For their study, 550 people with MS were matched by gender and birth year to 299 health volunteers. Blood samples from all of the participants were exposed to an enzyme that binds to antibodies that fight H. pylori. Antibodies in a person’s blood indicate that they’ve had past exposure to a particular bacterium.

Antibodies are the immune system’s way of remembering an infection and making us immune to it in the future. That’s why vaccinations work to prevent disease: tiny amounts of the actual infectious agent are introduced in order to prompt the immune system to make protective antibodies. The antibodies will prevent a serious reaction during a real-life exposure later on.

Only 14 percent of the study’s female volunteers with MS tested positive for H. pylori antibodies, compared to 22 percent of their healthy peers. This suggests a connection between MS and H. pylori, but it’s too soon to draw any cause-and-effect conclusions.

Moreover, in the women with MS who tested positive for these antibodies, the more antibodies they had, the less severe their disease course appeared to be. This indicates that the antibodies may play some role in regulating the immune system.

Understand More About Antigens and Antibodies »

Curiously, the study’s male participants with MS didn’t match the females when it came to H. pylori. The antibody levels in the men with MS were no different from that of their matches in the control group.

A common bacterium that is thought to be spread from one person’s mouth to another, the “helico” part of the Helicobacter pylori name refers to its spiral shape — like helicopter blades. Children are thought to be most at risk for H. pylori infection because they haven’t yet learned to practice good hygiene.

H. pylori is usually acquired in infancy from family members,” explained Kermode in an interview with Healthline.

When the bacteria take up residence in the stomach, most people are able to fight them off without incident. But for some people, the invader can wreak havoc, causing damage to the mucus lining of the stomach resulting in painful ulcers.

Learn More About Stomach Ulcers and What Causes Them »

However, new research on the microbes that naturally live in the human gut has shown that H. pylori may actually protect younger people from asthma, allergies, and gastroesophageal reflux disease. It does this by adjusting levels of stomach acid and helping to train the immune system to recognize friend from foe.

This brings an old scientific theory back up for discussion. The “hygiene hypothesis,” around since the 1980s, suggests that exposure to germs early in life might be necessary to prime the immune system and suppress the development of autoimmune diseases later in life.

The use of hand sanitizers and antibiotics has been cited as one possible reason for the rising rate of autoimmune diseases like MS and celiac disease in the Western world.

“Although recent research has found that previous infection with the stomach bacteria Helicobacter pylori was associated with a lower risk of developing MS in women and less severe disability was seen among those women with evidence of infection, more research is needed to determine if a cause-effect relationship exists,” Dr. Bruce Bebo, Executive Vice President of Research at the National MS Society, told Healthline in a prepared statement.

Given that fewer women with MS test positive for H. pylori and that exposure to it may provide protection against MS, is it possible that H. pylori may one day be used as part of a vaccine for MS?

The idea of using a tailored bacterial cocktail to treat or prevent disease is a “very exciting idea,” Kermode said. “If not H. pylori, then some other antigenic stimulus in infancy. Equally exciting, using the H. pylori bacteria itself to deliver antigenic therapies,” he added. That would mean using H. pylori as a vector to deliver helpful drugs or other compounds as it infects the body.

If scientists can figure out how childhood infection with H. pylori or other bacteria influences the immune system, perhaps they can create drugs to mimic the effect or even harness the bacteria itself to treat or prevent autoimmune diseases.

Discover the Trillions of Bacteria Living Inside You Right Now »