A new study led by the University of California San Diego School of Medicine researchers has found that those people who suffer from migraines tend to have certain kinds of oral microbes which feed on nitrates commonly found in suspected triggers like wine and chocolate.

About 38 million Americans are afflicted with migraines, a condition which has largely remained a mystery to the medical community. 
However, a new study led by the University of California San Diego School of Medicine has found that the extreme headaches may be linked with bodily microbes. 
As one of the authors has explained in a news release, the research was prompted by a common theory that “certain foods trigger migraines--chocolate, wine, and especially foods containing nitrates.” 
So the team accessed the American Gut Project database to analyze the bacteria in 172 oral and nearly 2,000 fecal samples. 
They found that those participants who admitted to migraines were more likely to have the kind of microbes that break nitrates down into nitrites.
Because nitrites can be further reduced to nitric oxide, a substance associated with migraines, the team concluded that the bacteria, especially those found in the mouth, are also a likely factor. 
The researchers’ next step is to further examine oral bacteria and the frequency and severity of migraines.