A team of scientists from the University of Chicago and the University of California, San Diego, has found that migraine sufferers harbor significantly more nitrate-reducing bacteria in their mouths compared to people who do not get migraines.
According to a new study, the mouths of migraine sufferers harbor more nitrate-reducing microbes than people who do not get migraine headaches. Image credit: Sasha Wolff / CC BY 2.0.
Nitrates, found in foods like processed meats, green leafy vegetables, and in cardiac medications, can be reduced to nitrites by bacteria found in the oral cavity.
These nitrites when circulating in the blood can then be converted to nitric oxide under certain conditions, which is a powerful vasodilator that can aid cardiovascular health by improving blood flow and reducing blood pressure.
“There is this idea out there that certain foods trigger migraines — chocolate, wine, and especially foods containing nitrates,” said study lead author Antonio Gonzalez, from the University of California, San Diego.
“We thought that perhaps there was a connection between someone’s microbiome and what they were eating.”
Using data from the American Gut Project, the team sequenced bacteria found in 172 oral samples and 1,996 fecal samples from healthy participants. The participants had previously filled out surveys indicating whether they suffered from migraines.
The sequencing first told them which bacterial species were found in different abundances between migraineurs and non-migraineurs.
In terms of bacterial community composition, the team did not find huge differences in either fecal or oral samples from migraineurs compared to non-migraneurs.
Next, the researchers used an innovative bioinformatic tool to analyze which genes were likely to be present in the two different sets of samples, given the bacterial species present.
In fecal samples, the scientists found a slight, but statistically significant increase in the abundance of genes that encoding nitrate, nitrite and nitric oxide reductases in migraineurs.
In oral samples, these genes were significantly more abundant in migraineurs.
“We know for a fact the nitrate-reducing bacteria are found in the oral cavity. We definitely think this pathway is advantageous to cardiovascular health, but now we have a potential connection to migraines as well,” said co-author Dr. Embriette Hyde, also from the University of California, San Diego.
About 80% of cardiac patients who take nitrate-containing drugs report severe headaches as a side effect.
The researchers speculate that we may have a symbiotic relationship with our oral bacteria, which aids our cardiovascular health.
But for certain people, this study suggests, too many nitrate-reducing bacteria in the mouth may also lead to migraines.
“Our results show for the first time a potential link between bacterial nitrate, nitrite, and nitric oxide reducers and migraines, by reporting their higher abundances in the oral cavities of people with migraines than in the oral cavities of those who do not suffer from migraines,” the scientists said.
“Future studies should focus on further characterizing the connection between oral bacterial nitrate, nitrite, and nitric oxide reducers and migraines.”
The research was published online October 18, 2016 in the journal mSystems.
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Antonio Gonzalez et al. Migraines Are Correlated with Higher Levels of Nitrate-, Nitrite-, and Nitric Oxide-Reducing Oral Microbes in the American Gut Project Cohort. mSystems, published online October 18, 2016; doi: 10.1128/mSystems.00105-16
