Why does red wine give some people a headache? Science has the answer

Image by Mick Stephenson (CC BY-SA 3.0)

The answer to ‘why does red wine give some people a headache?’ is not because too much is drunk (although that is obviously a factor). It stands that for many people even a small glass of red vino is sufficient to trigger a headache.

The reason for this has been traced to a molecule that is naturally found in red wine termed quercetin. This substance can disrupt the metabolism of alcohol and cause a severe headache.

Quercetin is a flavanol, naturally found in grapes and has hitherto been associated with antioxidant properties (to the extent that some people take it as a dietary supplement, with questionable benefits notwithstanding).

In terms of those who experience an unwanted reaction in the form of a headache, Andrew Waterhouse, a professor emeritus at the University of California (UC) Davis picks up the story: “When it gets in your bloodstream, your body converts it to a different form called quercetin glucuronide. In that form, it blocks the metabolism of alcohol.”

This leads to the build-up of acetaldehyde, which a known toxin that has been linked to flushing, headache, and nausea. In addition to toxicity, the molecule is an irritant and inflammatory substance. For instance, high levels of acetaldehyde can cause facial flushing, headache and nausea.

The researchers think that if certain susceptible people drink even a little bit of wine that contains quercetin, they get headaches, especially if they have a susceptibility to headaches or migraines.

At present this is a working hypothesis. The next step is to test this scientifically on people who develop these headaches.

It also stands that the levels of quercetin vary significantly from one red wine to another. The molecule is generated in grapes when exposed to sunlight, so when clusters are exposed, there are consequently higher levels of quercetin. The scientists wish to assess the effects of red wines with very little quercetin compared to those with a lot, to see if this theory accurately reflects what people experience.

As an example, the grapes grown in Napa Valley that are used to produce cabernets are one example; they have quercetin levels that are four or five times higher than other red wines. Another contributing factor is where different aspects of wine production, like fermentation or aging, produce varying amounts of quercetin.

It remains unknown why some people are more prone to headaches after red wine consumption than others. A possibility is that some individuals may have enzymes that are more likely to be impaired by quercetin, or some may be more affected by acetaldehyde build-ups.

The research appears in the journal Scientific Reports titled “Inhibition of ALDH2 by quercetin glucuronide suggests a new hypothesis to explain red wine headaches.”