What if migraines were all in your mouth?
A new study found that people who experienced migraines had higher concentrations of microbes in their mouths that modify nitrates. Consuming nitrates is associated with migraine frequency and intensity.
Nitrates are chemicals found in processed foods, leafy green vegetables and some medications. They are reduced to nitrites by bacteria in the mouth and can be converted to nitric oxide in the blood. Nitric oxide can improve blood flow and reduce blood pressure.
Nitroglycerin--which is a nitrate--is used in oral medications by people who have heart problems, but headaches are a common side effect.
"There is this idea out there that certain foods trigger migraines—chocolate, wine and especially foods containing nitrates," first author Antonio Gonzalez, PhD, said in a press release. "We thought that perhaps there are connections between what people are eating, their microbiomes and their experiences with migraines."
Dr. Gonzalez is a programmer analyst in the laboratory of Rob Knight, PhD, professor and director of the Center for Microbiome Innovation at UC San Diego and senior author on the study.
Dr. Gonzalez and Embriette Hyde, PhD, examined bacteria from 172 oral samples and 1,996 fecal samples from healthy participants who had completed surveys indicating whether they experienced migraines. They applied gene sequencing techniques to identify the specific bacteria.
Although the types of bacteria were similar in both patients who had migraines and those who didn't, the composition was different. People who had migraines had more microbes that produced nitrate, nitrite and nitric oxide-related enzymes.
"We know for a fact that nitrate-reducing bacteria are found in the oral cavity," Dr. Hyde, project manager for the American Gut Project and assistant project scientist in the Knight lab, said in the press release. "We definitely think this pathway is advantageous to cardiovascular health. We now also have a potential connection to migraines, though it remains to be seen whether these bacteria are a cause or result of migraines, or are indirectly linked in some other way."
The scientists plan to study this issue in more detail to determine how circulating nitric oxide correlates with migraine status.
The study was published in the October issue of mSystems, the official journal of the American Society of Microbiology.
The study did not receive outside funding and none of the authors reported a conflict of interest.
