Could migraines really be triggered by gut bacteria?

Migraines are the third most common disease world-wide, thought to affect around one in seven people in some way. Shockingly, it is estimated that the UK loses 25 million work and school days a year due to migraine. This is an overwhelming statistic, thought to cost the country approximately £2.25 billion a year in lost work days alone.

As such, researchers are on the lookout for treatments that may help improve the quality of life for these people.

A new study (1) has been published, looking at how bacteria living in the guts of people with migraines differ from those not affected.

So what is the study about?

The study, published in the Journal mSystems for the American Society of Microbiology, included over 2,000 individuals so it had a relatively good sample size. The researchers found that migraine sufferers had higher levels of a type of bacteria in their mouths that break down nitrates in our foods compared to unaffected people. Nitrates are then broken down to form nitrites and then nitric oxide in the bloodstream. This is a substance that has been linked in the past to headaches, so this could be a very useful finding.

The idea for this study originated from the fact that nitrate-based medications are used for heart conditions including angina, but also are known to bring a very high risk of headache with them. Up to 80% of people that take these medications have headaches as a side effect, and in 10 % the headaches are so severe they have to cease treatment. As such a postulated link between headaches and nitrates has existed for a long time.

For many years, migraine sufferers have linked certain triggers to their migraines including chocolate, wine, processed meats - interestingly, foods that are high in nitrates.

The theory is that if these people have higher levels of the bacteria in their mouths that convert nitrates into nitrites and eventually the headache causing nitric oxide, it can trigger their migraines. It has to be added however that this study can only show a trends, not a causal association.

The suggestion has been raised that in individuals suffering migraines, could their symptoms possibly be controlled by altering the bacteria that reside in their mouths? At present we do not know. This piece of research, although interesting, is not going to give us a definitive answer.

The researchers state that it remains unclear whether the difference in bacteria itself causes the migraines or whether the migraines themselves cause the different levels of bacteria.

In addition, the same bacteria thought to be linked to migraines are thought to have a beneficial effect on cardiovascular health (the health of our hearts and circulation). If these bacteria were simply reduced throughout the gut by treatment, it is thought that it be detrimental to the cardiovascular system. There is no easy answer.

Irrespectively, the study has yielded interesting and promising results in terms of making progress towards better understanding and in turn future possible treatments.

In the meantime migraine sufferers are advised to avoid triggers such as chocolate and wine if affected and to consult your doctor should your symptoms worsen or change.


1. Gonzalez A, Hyde E, Sangwan N, 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 19 2016.


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