Sweet Pain: Why drinking red wine may give you a headache

Many people love drinking a glass of red wine – either with a meal or on its own as a little treat. But for some, even a small amount of red wine leads to a headache. Now, scientists seem to have unlocked the mystery behind this phenomenon. Let’s take a closer look: The study, conducted by scientists from the University of California, was published in the journal Scientific Reports, as per Newsweek. “We think we are finally on the right track toward explaining this millennia-old mystery,” said co-author Morris Levin, professor of neurology and director of the Headache Center at the University of California, San Francisco. So, what’s the answer?

Researchers are pointing the finger at quercetin, which is a compound and flavanol in fruits and vegetables.

“Quercetin is produced by the grapes in response to sunlight,” wine chemist and co-author Andrew Waterhouse, professor emeritus with the UC Davis Department of Viticulture and Enology, told the outlet. “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." While quercetin is supposed to be good for you, adding alcohol to the mix changes things. “When it gets in your bloodstream, your body converts it to a different form called quercetin glucuronide,” Waterhouse explained. “In that form, it blocks the metabolism of alcohol.” The role of acetaldehyde in the human body is also under the scanner. But before we come to that, let’s briefly examine acetaldehyde how our body breaks down alcohol. It usually does so through two enzymes — alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) – which shred the alcohol molecules and remove it from the body. ADH first converts alcohol to acetaldehyde. Acetaldehyde is then further processed to acetate. Acetate itself is turned into water and carbon dioxide and then passed out of the body. “Acetaldehyde is a well-known toxin, irritant and inflammatory substance,” lead author Apramita Devi, postdoctoral researcher with the UC Davis Department of Viticulture and Enology, told Newsweek. “Researchers know that high levels of acetaldehyde can cause facial flushing, headache and nausea.” But how does it work? Waterhouse also told ZME Science that though any alcoholic beverage can give you a headache, only red wine brings one on instantaneously. “Our hypothesis is that quercetin, which is found only in red wine (only traces in white wine), inhibits ALDH2 and that results in high circulating levels of acetaldehyde, and that causes headache. The quercetin is not metabolized. It blocks the metabolism (or breakdown) of acetaldehyde, and the accumulation of that is what causes inflammation, the result of which is headache.” “Quercetin itself does not cause headaches, but only the combination of alcohol and quercetin.  This may be why it has taken so long to sort this out.  It isn’t a direct effect,” Waterhouse added. But some remain sceptical. Professor Roger Corder, an expert in experimental therapeutics, at Queen Mary University of London, told BBC News anecodatal evidence points to cheaper wines.

Corder said it might be a good idea to examine the additives used in making such wines.

Corder also pointed to pectinases which accelerate the release of anthocyanins which in turn speeds up winemaking as well as dimethyl dicarbonate – used to preserve lower-price vintages. As per The Guardian, the team is now looking to test their theory via a clinical trial in which wines with varying levels of quercetin would be given to subjects. Waterhouse remains upbeat. “If our hypothesis works out in future studies, I hope it will be possible for consumers to find out more about the levels of quercetin in the wine they buy,” he told ZME Science. “It will be potentially very helpful for people who drink red wine to be able to choose wines less likely to cause headaches,” added Levin. “Also, winemakers may use our findings to reduce quercetin in their wines.”