How your mouth is linked to your migraines

Story highlights

  • Microbes in your mouth are linked to migraines, a new study suggests
  • The connection sheds light on why certain foods can trigger migraines

(CNN)Your vision starts to blur. You see flashing lights. You feel that familiar throbbing pain in your head grow stronger and stronger.

About 12% of Americans experience these migraines, and a new study suggests they could be blamed on the bacteria living in their mouths.
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    People who get migraines have a higher abundance of mouth bacteria that reduce compounds called nitrates into nitrites, which can be converted into nitric oxide, according to the study published Tuesday in the American Society for Microbiology's open-access journal mSystems.
    Having increased nitric oxide in your bloodstream has been associated with migraines in separate research.
    Now, the study sheds light on how foods that contain nitrates, such as hot dogs and lunch meats, might trigger migraines.

    'A complicated puzzle'

    If a solid link between mouth bacteria and migraines can be established, it also might lead to new ideas for treatment, said Embriette Hyde, assistant project scientist at the University of California, San Diego School of Medicine and a co-author of the study.
    "One can imagine a targeted treatment, such as mouthwash or the introduction of a probiotic species. However, this will be really complex," she said, because the bacterial balance is a delicate one. "It's certainly a complicated puzzle."
    For the study, researchers analyzed data from the American Gut Project on bacteria found in the mouths of 172 healthy participants and the feces of 1,996 healthy participants. Each participant also had completed a survey indicating whether they had a history of migraines.
    As the researchers compared the genomes of the bacteria found in people who have migraines with those who don't have migraines, they discovered an eyebrow-raising difference.

    Understanding your microbiome

    Bacterial genes that reduce nitrates into nitrites and nitric oxide were significantly more abundant in the mouths of people who have migraines than those who don't, the researchers found. A slight increase in their abundance was also found in the feces samples.
    The human gut hosts a complex community of trillions of microbes, called a microbiome, but more research is needed to understand how your microbiome affects migraines, said Hyde, who is also a project manager for the American Gut Project.
    "While the link between migraines and nitrates has been known for a while, researchers still aren't sure about the nature of this link. We know it depends on eventual formation of nitric oxide, but the exact mechanism hasn't been established yet," Hyde said. "This study is very preliminary, and while the findings are exciting, we need to confirm them in a larger, targeted cohort."
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    The study appears to be the first to show a difference in the gut bacteria of people with migraines compared with those who don't have migraines, said Dr. William Young, a physician and specialist in neurology at Thomas Jefferson University Hospital in Philadelphia, who was not involved in the study.
    "You're not just the person you are, you're also, medically speaking, the bugs that live in your gastrointestinal system, and that could play a part in a lot of medical diseases and possibly, according to the study, migraine," Young said.
    However, "the problem with the study is correlation is not causation," he added. "It could well be other reasons why people with migraine have different gut bacteria."