Why do most people get headaches after consuming red wine?

The nights are long and the weather is cold, which means we're officially in red wine season.

But for many people, wine consumption can also cause headaches. Many people and scientists have known that after summer, maybe after 30 minutes, a headache starts, but recently they discovered the reason why.

Researchers from the University of California, Davis, have discovered that a flavanol, or nutrient, found in red wine stops the body from processing alcohol properly.

Ironically the flavanol in question, quercetin, is considered a good antioxidant and is even available as a health supplement. But when processed or metabolized with alcohol, it turns into an evil.

"When it enters your bloodstream, your body converts it into another form called quercetin glucuronide," said wine chemist and corresponding author Andrew Waterhouse, professor emeritus in the Department of Viticulture and Enology at UC Davis.

"In that form, it blocks the metabolism of alcohol, which results in the accumulation of the toxin acetaldehyde, and this leads to headaches," says lead author Dr Apramita Devi.

"Acetaldehyde is a known toxic, irritating and inflammatory substance. "Researchers know that high levels of acetaldehyde can cause facial flushing, headaches and nausea," Dr Devi said.

Some people are genetically better at metabolizing acetaldehyde, which helps explain why not everyone is affected in the same way. For example, in about 40% of the East Asian population, the enzyme that breaks down acetaldehyde does not work properly. "We suggest that when susceptible people consume wine with even modest amounts of quercetin, they develop headaches, especially if they have an existing migraine or other primary headache condition," said co-author Morris Levin, professor of neurology and director of the University of California, San Francisco Headache Center.

Different red wines have different levels of the flavanol quercetin, depending on how the wine is made. "Quercetin is produced by grapes in response to sunlight," said Professor Waterhouse. “If you grow grapes with exposed bunches, like they do in Napa Valley for their cabernets, you get much higher levels of quercetin. In some cases, it can be four to five times higher."

Older wines also appear to have higher levels of quercetin, while pinot noir and cabernet sauvignon wines have the most flavanols overall.

The team will now begin investigating red wine-induced headaches using wines containing different levels of quercetin, to validate their theory and better understand why some people are more sensitive to them than others. others.

They will observe whether the enzymes of people suffering from red wine headaches are more easily inhibited by quercetin, or if this population is more easily affected by the accumulation of the toxin acetaldehyde.

"We think we are finally on the right track to explaining this millennia-old mystery," said Professor Levin.

The study was published in the journal Scientific Reports.