Dr Ray says that the idea that quercetin causes wine headaches is still a theory.
Wine headaches have been a source of complaints since ancient Greece. While headaches can result from any alcohol, especially for those prone to migraines, red wine seems notably troublesome. Yet, the exact catalyst behind this phenomenon remains unclear to scientists.
"This puzzle has been around for literally thousands of years," said Dr Morris Levin, director of the Headache Center at the University of California, San Francisco, Medical Center. "There are a lot of ingredients in wine that could conceivably cause a headache, not the least of which is just alcohol itself."
A study published in the journal Scientific Reports says that an antioxidant found in grape skins affects how your body processes alcohol, leading to the buildup of a toxic byproduct that causes headaches, the New York Times reported.
A wine headache, occurring within the initial three hours of consuming a drink, differs from a hangover, which sets in later.
One idea is that allergies are to blame for that achy, throbbing feeling. Some people are sensitive to histamines, which are found in many fermented foods, including red wine. But studies testing the histamine hypothesis found no difference in people's responses to pinot noirs with low and high levels of histamines, or when people were given an antihistamine before drinking a glass of Sangiovese.
A potential cause of headaches could be an allergy to sulfites, a preservative in wine. However, no studies conclusively prove that sulfites in red wine induce headaches, and other sulfite-rich foods like dried fruits and soy sauce lack the same reputation.
Scientists currently lean towards a theory involving polyphenols, encompassing tannins and antioxidants in red wines. Identifying the specific compounds responsible or understanding how they trigger headaches remains a challenge. Interestingly, other high-polyphenol foods like tea, chocolate, onions, and berries don't exhibit a strong association with headaches.
The new study says that red wine headaches might result from a combination of alcohol and a specific polyphenol-quercetin, an antioxidant.
"In small amounts, we can handle" acetaldehyde without feeling sick, said Lara Ray, a psychology professor at the University of California, Los Angeles, who specializes in alcohol use disorders and was not involved in the study. But when alcohol isn't metabolized properly, "the body then shows this aversive response."
During laboratory experiments, it was observed that quercetin, an antioxidant generated by grapes upon exposure to sunlight, exhibited this characteristic, the New York Times reported. "We refer to this as sunscreen for grapes," said Andrew Waterhouse, a professor emeritus of oenology (wine chemistry) at the University of California, Davis, and an author of the study.
However, Dr Ray says that the idea that quercetin causes wine headaches is still a theory.
The team aims to validate the hypothesis by conducting a clinical trial to examine the headache-inducing effects of red wines with varying quercetin levels. The findings from this study could provide valuable insights for individuals seeking to prevent red wine-induced headaches in the future. Quercetin, produced by grapes in response to sunlight, is more abundant in grapes grown in exposed clusters like Napa Valley cabernets, potentially containing five times more quercetin than other red varieties. Additionally, factors such as skin contact during fermentation, fining processes, and ageing also influence quercetin levels.
Morris Levin said, "It will be potentially very helpful for people who drink red wine to be able to choose wines less likely to cause headaches. Also, winemakers may use our findings to reduce quercetin in their wines."