Any alcohol, and red wine in particular can cause some people to wake up with a throbbing headache within a few hours, at times only after half a drink. Over the years, several reasons have been given as the potential reasons; it is confounding that not everyone reacts to it, and even at different intensity but a recent study by U.C Davis claims it is perhaps Quercetin, a flavanol found in red wines that gives the headache, though it’s unclear why these headaches affect only certain individuals.

Quercetin is a plant pigment (flavonoid found in many plants and foods, such as red wine, onions, green tea, apples, and berries.) that  has antioxidant and anti-inflammatory effects that might help reduce swelling, kill cancer cells, control blood sugar, and help prevent heart disease. According to the Study, there’s a lot of variability in the amount of quercetin found in different types of red wines.

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Quercetin is a healthy antioxidant, but when it’s consumed with alcohol, it can create problems, according to researchers. Once quercetin is in the body, it is converted into a liver metabolite called quercetin glucuronide. When alcohol is also being consumed, it may cause levels of acetaldehyde, an irritating and inflammatory substance to increase in the body.

Acetaldehyde is somewhat toxic and several symptoms occur, including headaches and other symptoms,” says Andrew Waterhouse, professor emeritus with the Department of Viticulture and Enology at the University of California, Davis, with whom I interacted on a couple of occasions at Wine and Health Conferences in Napa. He has done a lot of work in the area of wine tannins and other variables and is a widely respected authority on the subject of pigments, tannins etc.

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Prior evidence shows that a high amount of acetaldehyde is linked to headache, flushing, rapid heartbeat and nausea. For some people, these headaches can start occurring within 30 minutes to three hours after even a small glass of wine.

Past research had suggested that other compounds, like sulphites, phenolic flavonoids or tannins, might be the reason wine drinkers develop headaches. However, other foods high in phenolic compounds, including flavonoids, don’t have this effect.

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This inconsistency has led scientists to question whether something else is going on. This study suggests that quercetin may actually be the culprit, at least when it comes to red wines. It’s still unclear why some people experience red wine headaches and not others. They may be more sensitive to acetaldehyde, or their bodies might metabolize quercetin differently. It might also be that they have an underlying predisposition for having migraine, which becomes triggered by increased acetaldehyde. Prof Waterhouse has no answer and says future studies will need to investigate who is most at risk.

The flavanol levels also vary significantly in different types of red wines and largely depend on how the grapes are grown. Quercetin increases when grapes are exposed to sunlight. Red wines tend to have dramatically higher levels of quercetin. In fact, grapes exposed to sun can have four to eight times as much quercetin compared to grapes grown in shade, according to past data. Other factors, including the aging and fermentation processes, can also influence how much quercetin is in grapes.

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According to Waterhouse, cheaper reds generally contain less quercetin since the grapes used are typically exposed to less sunlight. It is likely that some high-quality reds might still be safe. “I have been getting many emails from readers; one even confirmed that she could drink less expensive red wines, but the good wines sadly end up in cooking,” says Waterhouse. Many people have had better luck with Pinot Noir and Syrah wines.

Alcohol content could also increase the risk of a headache in those who are prone to headaches, so it may be worth avoiding high-alcohol wines like the high-octane cabernet sauvignons. You can opt for a white wine, as they contain smaller doses of quercetin, suggests Waterhouse.

UC Davis researchers think the flavanol quercetin, when combined with alcohol, may be the cause of red wine headache. The medication disulfiram prescribed to alcoholics to prevent them from drinking, causes these same symptoms. That is 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 Asians also have an enzyme that doesn’t work very well, allowing acetaldehyde to build up in their system.

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Hopefully, one day we’ll have a test that can quickly measure the amount of quercetin in any given bottle of wine, but for now, your best bet is to monitor how your body reacts to different types of red wine , and when in doubt, go for the cheap bottle of Syrah. Your head may thank you; your wallet certainly will.

“We postulate that when susceptible people consume wine with even modest amounts of quercetin, they develop headaches, ” said co-author Morris Levin, professor of neurology and director of the Headache Center at the University of California, San Francisco, adding, ‘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’.

Scientists will next compare red wines that contain a lot of quercetin with those with very little, to test their theory about red wine headaches on people. “If our hypothesis pans out, then we will have the tools to start addressing these important questions,” Waterhouse said.

Subhash Arora