New York, Oct 19 (IANS): Researchers have found that the mouths of migraine sufferers harbour significantly more microbes with the ability to modify nitrates than people who do not get migraine headaches.

"There is this idea out there that certain foods trigger migraines -- chocolate, wine and especially foods containing nitrates," said study first author Antonio Gonzalez from University of California San Diego in the US.

"We thought that perhaps there are connections between what people are eating, their microbiomes and their experiences with migraines," Gonzalez noted.

Nitrates, found in foods such as processed meats and green leafy vegetables and in certain medicines, can be reduced to nitrites by bacteria found in the mouth. 

When circulating in the blood, these nitrites can then be converted into nitric oxide under certain conditions. Nitric oxide can aid cardiovascular health by improving blood flow and reducing blood pressure. 

However, roughly four in five cardiac patients who take nitrate-containing drugs for chest pain or congestive heart failure report severe headaches as a side effect.

To better understand the link, the researchers 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 bacterial gene sequencing found that bacterial species were found in different abundances between people who get migraines (migraineurs) and non-migraineurs. 

In fecal samples, the researchers found a slight but statistically significant increase in the abundance of genes that encode nitrate, nitrite and nitric oxide-related enzymes in migraineurs. 

In oral samples, these genes were significantly more abundant in migraine sufferers

The study was published in the journal mSystems.