Why do red wines give some people headaches? There have numerous unproven culprits: sulfites, histamines or maybe just too much alcohol. But a new study, published in Scientific Reports by researchers at the University of California, Davis, has found that one of the healthier polyphenols in red wines keeps some people from quickly metabolizing alcohol, which can lead to an aching head.
Quercetin is a type of polyphenol called a flavanol, 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. Scientific research has linked it to some of red wine’s health benefits.
When you consume alcohol, your body uses a two-step process to break it down. Alcohol is metabolized in the liver, converted to acetaldehyde by an enzyme called alcohol dehydrogenase (ADH). The liver then breaks down acetaldehyde acetate with a second enzyme, aldehyde dehydrogenase (ALDH).
When you drink too much alcohol too rapidly, acetaldehyde builds up before it can be converted, which can produce adverse effects. But some people suffer from these conditions from just a little red wine, including many people of East Asian ancestry.
“Acetaldehyde is a well-known toxin, irritant and inflammatory substance,” said the study’s lead author, Apramita Devi, a post-doctoral researcher with the UC Davis Department of Viticulture and Enology. “Researchers know that high levels of acetaldehyde can cause facial flushing, headache and nausea.”
For this study, Devi and colleagues looked at how various polyphenols in red wine react with the enzymes that metabolize acetaldehyde. They found quercetin showed the highest inhibitory activity.
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“When [quercetin] 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 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, leading to a headache, flushing and an unpleasant evening.
“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 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.”
Scientists at the Headache Center will launch the next phase of this research. They plan to 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 clinical trial is funded by the Wine Spectator Scholarship Foundation, which is dedicated to supporting education in the wine, food and hospitality industries.
Waterhouse and Devi say there are still many unknown factors behind red wine headaches, particularly why some people seem more susceptible. “If our hypothesis pans out, then we will have the tools to start addressing these important questions,” said Waterhouse.
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