The director of the Headache Center at the University of California, San Francisco, Morris Levin, said they are “finally on the right track toward explaining this millennia-old mystery.”

“The next step is to test it scientifically on people who develop these headaches.”

It is believed that when the liver breaks down a particular ingredient in red wine, the result has the same effects as a drug used by alcoholics to make them feel ill after drinking.

According to Scientific Reports, the researchers focused on phenolic flavonoids, which come from grape seeds and skin and also contribute to the colour of red wine.

This was focused on after other components found in red wine, such as tannins, sulphites, and biogenic amines, were ruled out as causes of the headaches.

When researchers tested the different components in red wine, a flavanol called quercetin caught their attention.

Almost exclusively found in red wine, the component is processed by the body into different substances, but one of these, quercetin glucuronide, may hold the key to the answer.

Quercetin glucuronide blocks the enzyme that converts acetaldehyde into acetate, and when acetaldehyde builds up in the bloodstream, it can lead to headaches and nausea.

Some people may be more susceptible to feeling the effects of a buildup of acetaldehyde, and that is why they feel red wine headaches more than others.