Some people cannot drink red wine, even in small quantities, because it gives them a headache. Now, a study published in ‘Science Advances’ explains why.
A team from the University of California at Davis (USA) accuses a flavanol, a compound found naturally in red wines, that can interfere with the proper metabolism of alcohol and cause headaches.
Specifically, this flavanol is called quercetin and is naturally present in all types of fruits and vegetables, including grapes. It is considered a healthy antioxidant and is even consumed as a supplement. But when metabolized with alcohol, it can be problematic.
“When it reaches the bloodstream, the body converts it into a different form called quercetin glucuronide,” explains Andrew Waterhouse of the Department of UC Davis Viticulture and Enology. “In this way, it blocks the metabolism of alcohol.”
The buildup of acetaldehyde toxin causes redness, headache, and nausea.
As a result, people can end up accumulating the toxin acetaldehyde, explains lead author Apramita Devi.
“Acetaldehyde is a toxin, a well-known irritant and inflammatory substance,” says Devi. “Researchers know that high levels of acetaldehyde can cause facial redness, headache and nausea.”
The medicine disulfiram, prescribed to alcoholics to prevent them from drinking, causes these same symptoms. Waterhouse notes that this is because the medication 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 Asian population also has an enzyme that doesn’t work very wellallowing acetaldehyde to build up in your system.
“We believe that when susceptible people consume wine with even modest amounts of quercetin, they develop headaches, particularly if they have a preexisting migraine or other primary headache condition,” says co-author Morris Levin, professor of neurology and director of Headache. Center at the University of California-San Francisco. «We believe that we are finally on the right path towards explaining this ancient mystery. “The next step is to test it scientifically in people who develop these headaches.”
Furthermore, the levels of this flavanol can vary dramatically in red wine.
«Quercetin is produced by grapes in response to sunlight», says Waterhouse.
Quercetin levels can also differ depending on how the wine is made, including skin contact during fermentation, fining processes, and aging.
The scientists are planning a clinical trial with red wines that contain a lot of quercetin and red wines with very little to test their theory about red wine headaches in people.
Now, they recognize that there are still many unknowns about the causes of red wine headaches. It is not clear why some people seem more susceptible than others. Researchers don’t know if the enzymes in people who get red wine headaches are more easily inhibited by quercetin. or if this population is simply more easily affected by the buildup of the acetaldehyde toxin.