The nights are long and the breeze is chilly, which means it’s officially red wine season – but for many, that also means a sore head.
Scientists – and wine drinkers – have long known that even a small amount of red wine can cause a sudden headache, sometimes within 30 minutes, even if other alcoholic drinks don’t have the same effect.
Now however, they may know why.
Researchers from the University of California, Davis, have discovered a flavanol, or nutrient, found in red wine stops the body from processing alcohol properly.
Ironically the flavanol in question, quercetin, is considered a good antioxidant – it is even available as a health supplement. But when processed, or metabolised, with alcohol, it turns into a bit of a baddie.
‘When it 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 UC Davis Department of Viticulture and Enology.
‘In that form, it blocks the metabolism of alcohol.’
This results in the build up of the toxin acetaldehyde, and that leads to the headache, says lead author Dr Apramita Devi.
‘Acetaldehyde is a well-known toxin, irritant and inflammatory substance,’ said Dr Devi. ‘Researchers know that high levels of acetaldehyde can cause facial flushing, headache and nausea.’
Some people are genetically more adept at metabolising acetaldehyde, which helps explain why not everyone is affected in the same way. For example, in about 40% of the East Asian population, the enzyme that breaks down acetaldehyde does not function properly.
‘We [suggest] 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.
For those who love a tipple but not the accompanying headache, different red wines have different levels of the flavanol quercetin, depending on how the wine is produced.
‘Quercetin is produced by the grapes in response to sunlight,’ said Professor Waterhouse. ‘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.’
Older wines also appear to have higher quercetin levels, while pinot noir and cabernet sauvignon wines have the most flavanols overall.
The team will now begin investigating red wine headaches using wines containing differing levels of quercetin to validate their theory and better understand why some people are more susceptible to them than others.
Specifically, they will look at whether the enzymes of people who suffer from red wine headaches are more easily inhibited by quercetin, or is this population just more easily affected by the build-up of the toxin acetaldehyde.
‘We think we are finally on the right track toward explaining this millennia-old mystery,’ said Professor Levin. ‘The next step is to test it scientifically on people who develop these headaches, so stay tuned.’
The study is published in the journal Scientific Reports.
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