Researchers close in on revealing what causes red wine headaches

For as long as humans have been imbibing alcohol they have also been battling with the drug’s notorious side effects. Headaches and nausea often follow a few beverages due to the build up of a toxic by-product of alcohol – acetaldehyde.

When ethanol is metabolized by our liver the chemical acetaldehyde is left over. Acetaldehyde is incredibly toxic to a human body and when we can’t effectively clear it out, levels can build up leading to a variety of common unpleasant symptoms, including headache and facial flushing.

But one alcoholic beverage has a much more notorious history of inducing headaches. For centuries red wine has been thought to trigger headaches more than other drinks, and it has been unclear exactly why this could be the case. What is it specifically about red wine that seems to cause more headaches in people than other alcoholic drinks?

A variety of different hypotheses have been floated over the years. Some people believe the added sulphites in red wine generate an allergic response leading to headaches, while others have pointed to the high histamine content of red wine as a possible culprit. More recently some researchers have turned their focus to a group of compounds in red wine called flavanols.

A new study, from a team of scientists at University of California, Davis, zoomed in on about a dozen specific flavanols in red wine. The researchers wanted to know if any of these chemical compounds affected acetaldehyde metabolism.

The in vitro research swiftly highlighted one particular chemical – quercetin. On its own, quercetin is considered to be quite a beneficial flavanol. Found in many fruits and vegetables it is known for its anti-inflammatory effects. But the study found that when combined with alcohol, quercetin blocked the action of an enzyme our bodies use to break down acetaldehyde.

“When it gets in your bloodstream, your body converts it to a different form called quercetin glucuronide,” explained Andrew Waterhouse, corresponding author on the new study. “In that form, it blocks the metabolism of alcohol.”

Essentially the hypothesis is the more quercetin present in wine, the slower our bodies can metabolize acetaldehyde and this can lead to the toxic side effects of alcohol we all know and hate. Of course, this isn’t necessarily the entire story behind red wine headaches. After all, not everyone experiences these negative effects so acutely. Study co-author Morris Levin suggests those who suffer red wine headaches are likely to harbor other pre-existing conditions that make them more susceptible to the effects of quercetin.

“We postulate that when susceptible people consume wine with even modest amounts of quercetin, they develop headaches, particularly if they have a preexisting migraine or another primary headache condition,” said Levin. “We think we are finally on the right track toward explaining this millennia-old mystery.”

The researchers are now set to investigate their hypothesis in a small human clinical trial. They will look at the effects of different wines with varying quercetin concentrations on headaches in a human cohort.

The new study was published in Scientific Reports.

Source: UC Davis