For some people, drinking even a small amount of red wine will be followed by the onset of a headache within as little as 30 minutes.
In a new study, researchers have examined why this “red wine headache” happens, even to people who don’t get headaches when drinking small amounts of other alcoholic beverages.
According to a paper in Scientific Reports, a flavanol in grapes, quercetin, could be the culprit. Flavanols are a group of compounds found in many plants, including noteworthy concentrations in cocoa, teas, and grapes.
“When [quercetin] gets in your bloodstream, your body converts it to quercetin glucuronide. In that form, it blocks the metabolism of alcohol,” says co-author Andrew Waterhouse, professor emeritus with the University of California – Davis Department of Viticulture and Enology, in the US. (Spelled oenology in many countries – the study of wine.)
When we drink alcohol, it is metabolised or broken down by the body in several processes. The most common pathways involve two enzymes: alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH).
First, ADH breaks down alcohol into the toxin acetaldehyde, and then ALDH breaks down acetaldehyde. But glucuronide inhibits ALDH from doing its job and this causes the accumulation of the toxin acetaldehyde.
“Acetaldehyde is a well-known toxin, irritant and inflammatory substance. Researchers know that high levels of acetaldehyde can cause facial flushing, headache and nausea,” says lead author Dr Apramita Devi, postdoctoral researcher at UC Davis.
Some people have a dysfunctional acetaldehyde dehydrogenase and experience an accumulation of acetaldehyde in the body after drinking. Disulfiram, a potent inhibitor of ALDH, is also sometimes used to treat alcohol abuse as it causes uncomfortable symptoms, including headaches, when alcohol is consumed.
“We postulate that when susceptible people consume wine with even modest amounts of quercetin, they develop headaches, particularly if they have a pre-existing migraine or another primary headache condition,” says co-author Morris Levin, professor of neurology and director of the Headache Centre at the University of California, San Francisco.
The levels of quercetin can vary dramatically between red wines as a result of growing conditions and production processes.
“Quercetin is produced by grapes in response to sunlight. If you grow grapes with the clusters exposed, such as they do in the Napa Valley [in the US] for their cabernets, you get much higher levels of quercetin. In some cases, it can be four to five times higher,” explains Waterhouse.
At the moment, researchers don’t know if people who suffer from red wine headaches have ALDH enzymes that are more easily inhibited by quercetin, or if they are more easily affected by the buildup of acetaldehyde.
“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, so stay tuned,” adds Levin.