Why even a sip of red wine can give you a headache, according to a new study

If you’re one of the millions around the world who experience headaches from drinking even a few sips of red wine, a new study could explain it — and maybe even help solve the issue.

According to a study from a trio of Northern California scientists, published this week in the journal Scientific Reports, the cause could be quercetin: a flavonoid present in food such as onions, kale and seeds. Quercetin is especially prevalent in red-wine grapes.

“It’s a cool new theory,” said Dr. Andrew Waterhouse, an author on the study, a wine chemist and UC Davis professor emeritus.

On its own quercetin isn’t toxic but when ingested with alcohol and converted to another form, quercetin glucuronide, the study found that it can prevent the human body from metabolizing and detoxifying the wine’s alcohol.

This can cause a buildup of a chemical compound called acetaldehyde: a culprit that also contributes to hangovers. A primary enzyme converts acetaldehyde into something less toxic, and according to the new findings, this could be the key to understanding red-wine headaches.

The goal of the study was twofold: to help those who suffer from red-wine headaches identify the cause and hopefully avoid it in the future, and to help scientists and doctors understand the nature of migraines and headache mechanisms more generally.

Waterhouse previously attempted to answer a related question for a local winemaker who said they got headaches when drinking wines higher in alcohol; while he wasn’t able to solve that conundrum, it got the wheels turning. He contacted neurologist and headache specialist Dr. Morris Levin, the director of the University of California San Francisco Headache Center, who helped author the study.

Levin and his colleagues treat patients with a range of headaches; of the patients Levin sees, he says the majority find drinking red wine to be a problem.

“One of the things I’ve noticed over my career is how common it is for people to have a headache from drinking red wine,” Levin said. “You can get a headache after drinking white wine, you can get a headache after drinking any kind of alcohol, but red wine is a real common cause and it’s a centuries-old mystery as to why that happens.”

Waterhouse’s theory began simply: There are often more phenolic compounds in red wine than white wine, and one is known to relax blood vessels, which can cause headaches. But, Levin noted, severe headaches are often caused by inflammation — which phenols aren’t prone to causing.

Waterhouse racked his brain for wine components that can cause inflammation, and remembered the flushing reaction — as referred to by L.A. Times columnist Lucas Kwan Peterson and many others as “Asian glow” — that some people tend to have when drinking even a few sips of alcohol. Those who experience “glow” often also report headaches.

The glow phenomenon occurs during the metabolization process: In the first phase, for everyone, ethanolics are converted to acetaldehyde. In the second step, the acetaldehyde becomes acetic acid.

Why do some but not others get headaches while metabolizing quercetin? According to Levin, it’s all biology: Some don’t possess this enzyme in a large or effective enough quantity, resulting in larger acetaldehyde buildup, which can cause “glow” or flush.

Waterhouse realized that if the metabolizing enzyme were blocked with an ingredient of red wine, the same reaction of “glow” — and by proxy headaches — would happen.

That’s precisely what the study found. Apramita Devi, an author on the paper and a researcher at the UC Davis Department of Viticulture and Enology, noticed that a crucial enzyme was inhibited by the flavonoid, but only as it is metabolized with alcohol.

“This is one of the reasons why this hasn’t really been discovered before: [Quercetin glucuronide] on its own doesn’t cause headaches,” Waterhouse said. “In fact, it’s a great antioxidant and you can buy it at GNC and on Amazon. It’s a supplement. It’s just when it goes through this process.”

Human trials to further test the theory could begin as early as January, and will most likely occur at the UCSF Headache Center.

“The headache is one of the most disabling conditions in the world — it’s definitely in the top three — and we’re talking about many millions of people that have headaches,” Levin said. “I think maybe this work might shed a little more light.”

Should quercetin prove the culprit of red-wine headaches, Waterhouse said that this could help vintners to one day measure and label their wines, conveying quercetin levels to buyers.

In theory, he said, winemakers could produce red wines with less quercetin, though a key factor in developing grapes for wine is also what increases the flavonoid: sunlight.

According to Waterhouse, grapes grown with clusters exposed to sunlight can multiply the flavonoid’s presence by four to five times.

“Unless we figure out something else,” he said, “right now, if you grow one of your favorite cabernet grapes completely in the shade, the quality won’t be as good.”

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