Red wine may pair nicely with the upcoming Thanksgiving meal. But for some people, even small amounts of red wine can cause a headache.
Typically, a “red wine headache” can occur within 30 minutes to three hours after drinking as little as a small glass of wine.
For a new study, published in Scientific Reports, the researchers examined why this happens—even to people who don’t get headaches when drinking small amounts of other alcoholic beverages.
“We think we are finally on the right track toward explaining this millennia-old mystery.”
Researchers think that a flavanol found naturally in red wines can interfere with the proper metabolism of alcohol and can lead to a headache.
This flavanol is called quercetin, and it is naturally present in all kinds of fruits and vegetables, including grapes. It’s considered a healthy antioxidant and is even available in supplement form. But when metabolized with alcohol, it can be problematic.
“When it gets in your bloodstream, your body converts it to a different form called quercetin glucuronide,” says wine chemist and corresponding author Andrew Waterhouse, professor emeritus in the viticulture and enology department at the University of California, Davis. “In that form, it blocks the metabolism of alcohol.”
As a result, people can end up accumulating the toxin acetaldehyde, explains lead author Apramita Devi, postdoctoral researcher with the viticulture and enology department.
“Acetaldehyde is a well-known toxin, irritant, and inflammatory substance,” Devi says. “Researchers know that high levels of acetaldehyde can cause facial flushing, headache, and nausea.”
The medication disulfiram prescribed to alcoholics to prevent them from drinking causes these same symptoms. Waterhouse says that’s because the drug also causes the toxin to build up in the body when normally an enzyme in the body would break it down. About 40% of the East Asian population also has an enzyme that doesn’t work very well, allowing acetaldehyde to build up in their system.
“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,” says coauthor 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.”
Waterhouse says levels of this flavanol can vary dramatically in red wine.
“Quercetin is produced by the grapes in response to sunlight,” Waterhouse says. “If you grow grapes with the clusters exposed, such as they do in the Napa Valley for their cabernets, you get much higher levels of quercetin. In some cases, it can be four to five times higher.”
Levels of quercetin can also differ depending on how the wine is made, including skin contact during fermentation, fining processes, and aging.
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. The Wine Spectator Scholarship Foundation will fund the small human clinical trial.
The researchers say 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. The 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 buildup of the toxin acetaldehyde.
“If our hypothesis pans out, then we will have the tools to start addressing these important questions,” Waterhouse says.
Funding for this initial investigation came from people who supported the project via 2022 Crowdfund UC Davis.
Source: UC Davis