Oral Bacteria May Contribute to Migraines

Scientists know the release of chemicals around the nerves and blood vessels of the brain cause migraines headaches. Could oral bacteria be a trigger? 

According to the American Migraine Foundation, migraine headaches affect 37 million Americans and close to one billion people around the world. They are the sixth most disabling illness in the world and affect nearly one in four households in the U.S.

Scientists know the release of inflammatory chemicals around the nerves and blood vessels of the brain cause these debilitating headaches, but studies have not been able to pinpoint exactly what triggers this chemical release.

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Many migraineurs (those who suffer from migraines) have reported that specific foods trigger their headaches, leading to research investigating the link between diet and migraine attacks. One study found that alcohol, chocolate, and cheese appear to be common migraine triggers, as well as foods that contain preservatives such as dried fruit. The study also concluded that “the biological mechanism by means of [which] triggers in general and food in particular precipitate migraine attacks remains obscure.”

In other words, the researchers could see that those foods triggered migraine headaches but were unsure why.

Several other studies have found an association between nitrates, common in many trigger foods and sometimes used as preservatives, and migraine attacks. But researchers still remain unsure of exactly what the link between migraines and nitrates might be.

Another study seems to have found that link: the bacteria that live in your mouth.

The researchers, who were based at the University of California, San Diego, looked at data from the American Gut Project, a long-reaching study that uses samples provided by thousands of volunteers to learn about the human microbiome. They discovered an important difference between the microbes in the mouths of migraineurs and non-migraineurs.

Researchers first looked at the types of bacteria in the two groups and discovered that they were mostly similar. But the genetic makeup of the bacteria showed an important difference. Bacteria found in the mouths of migraineurs had abundant genes that modify nitrate, nitrite, and nitric oxide, significantly more than non-migraineurs.

Bacteria that live in your mouth and digestive system change nitrates — found in foods like red wine, leafy vegetables, and dried fruit — to nitrites. Nitrites then enter your bloodstream and are converted to nitric oxide, which causes vasodilation, or dilation of blood vessels. The process improves blood flow and reduces blood pressure. Though the nitrate-nitrite-nitric oxide cycle is critical for cardiovascular health, it is a process that only bacteria, not human cells, can perform.

The study’s authors speculate that, though we appear to have a symbiotic relationship with nitrate-processing bacteria that benefits our heart health, in some cases an overabundance of these bacteria may lead to over-dilation of blood vessels. That could be one of the causes of the blood vessel inflammation that leads to migraine headaches.

Adding weight to the theory, the study’s authors add, are known data about side effects in cardiac medications. Many of those medications are nitrate therapies, which are associated with migraines in 80 percent of the population. A further 10 percent are unable to tolerate nitrate therapies at all due to the severity of their headaches.

Unfortunately, the research does not yet offer treatment or management options for those suffering from migraines. But it does point scientists and doctors in a direction of inquiry that may eventually lead to new therapies or medications.

“These results,” the study’s authors conclude, “show for the first time a potential link between bacterial nitrate, nitrite, and nitric oxide reducers and migraines.”

Investigating that link is the next step in helping the millions of people who suffer from debilitating migraine headaches.

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