Why do some people get headaches from drinking red wine?

For some people, drinking red wine even in small amounts can cause a ‘red wine headache’. Now scientists at the University of California, Davis have examined why this happens and believe that a flavanol found naturally in red wines may be the culprit.

The flavanol called quercetin is naturally present in all kinds of fruits and vegetables, including grapes.

The level of this flavanol in each red wine can vary considerably as it depends on factors such as how long the grapes are exposed to sunlight and how the wine is made, including skin contact during fermentation, fining processes and aging.

While it is considered as a healthy antioxidant, Quercetin can be problematic for some people when metabolised with alcohol.

“When it gets in your bloodstream, your body converts it to a different form called quercetin glucuronide,” said wine chemist and corresponding author Andrew Waterhouse, Professor Emeritus with the UC Davis Department of Viticulture and Enology. “In that form, it blocks the metabolism of alcohol.”

As a result, people can end up accumulating the toxin acetaldehyde, explained lead author Apramita Devi, Postdoctoral Researcher with the UC Davis Department of Viticulture and Enology.

“Acetaldehyde is a well-known toxin, irritant and inflammatory substance,” Devi said. “Researchers know that high levels of acetaldehyde can cause facial flushing, headache and nausea.”

“We postulate that when susceptible people consume wine with even modest amounts of quercetin, they develop headaches, particularly if they have a pre-existing migraine or another primary headache condition,” said co-author Morris Levin, Professor of Neurology and Director of the Headache Center at the University of California, San Francisco. “We think we 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, so stay tuned.”

Clinical trial on wine headaches

Scientists will next compare red wines that contain a lot of quercetin with those that have very little to test their theory about red wine headaches on people. This small human clinical trial, funded by the Wine Spectator Scholarship Foundation, will be led by UCSF.

Researchers said there are still many unknowns about the causes of red wine headaches. It’s unclear why some people seem more susceptible to them than others. Researchers don’t know if the enzymes of people who suffer from red wine headaches are more easily inhibited by quercetin or if this population is just more easily affected by the build-up of the toxin acetaldehyde.

“If our hypothesis pans out, then we will have the tools to start addressing these important questions,” Waterhouse said.

The study was published in the journal Scientific Reports.

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