Researchers from the United States say they may have discovered why some people get a headache after just a small glass of red wine, even if they don’t feel the same effect when drinking other types of alcoholic drinks.
The University of California team claims, in a study, that this is due to a compound in red grapes that interferes with the way the body metabolizes alcohol.
The compound is an antioxidant or flavonol called quercetin.
They claim that Cabernet grapes, common in California’s Napa Valley, contain high levels of the substance.
High quality grapes
Red grapes produce more quercetin when they are exposed to sunlight.
This meant that more expensive red wines, rather than cheap red wines, would be worse for people prone to headaches, researcher Professor Andrew Waterhouse told BBC News.
“The cheaper grape varieties are grown on vines with very large canopies and lots of leaves, so they don’t get as much sun,” he said.
“Whereas high-quality grapes come from smaller harvests with fewer leaves.
“The amount of sunlight is carefully managed to improve the quality of the wine.”
But there are skeptics who doubt these conclusions.
Professor Roger Corder, an expert in experimental therapeutics at Queen Mary University of London, told BBC News that anecdotal evidence suggests that cheaper wines are worse for headaches. He argues that it would be more important to research the additives used in the production of low-quality mass-market red wines.
Other possible culprits
Several theories have been proposed to explain headaches caused by red wine, which can occur within 30 minutes of drinking even small amounts.
Some have suggested the culprit could be sulfites — preservatives meant to extend shelf life and keep wine fresh.
However, generally, the sulfite content is higher in sweet white wines than in red wines.
And although some people may be allergic to sulfites and should avoid them, there is little evidence that they are responsible for headaches.
Another possible culprit is histamine — an ingredient more common in red wine than in white or rosé.
Histamine can dilate blood vessels in the body, which can trigger a headache. However, again, absolute proof is lacking.
Experts know that more than one in three people of East Asian descent are intolerant to any type of alcohol — beer, wine and spirits — and will experience facial flushing, headache and nausea when drinking.
This is due to a gene that affects the effectiveness of an alcohol metabolizing enzyme called ALDH2 or aldehyde dehydrogenase.
Alcohol is broken down in the body in two steps – it’s converted into a toxic compound called acetaldehyde, which ALDH2 then turns into harmless acetate, basically vinegar.
If this cannot happen, harmful acetaldehyde builds up, causing the symptoms.
And researchers say a similar pathway is involved in red wine headaches.
They showed in the laboratory that quercetin can indirectly block the action of ALDH2, through one of its own metabolites.
Quercetin only becomes problematic when mixed with alcohol, according to the researchers, who funded their work through crowdfunding and have now published the results in the journal Scientific Reports.
Quercetin is also found in many other fruits and vegetables—and is even available as a health supplement due to its beneficial anti-inflammatory properties—and does not appear to cause headaches by itself.
The researchers have yet to prove their theory in people and say a simple experiment could be to give a quercetin supplement or a placebo pill to volunteers prone to red wine headaches along with a standard dose of vodka.
Professor Morris Levin, co-author and specialist in neurology and director of the Headache Center at the University of California, San Francisco, said:
“We’re finally on the right track to explaining this age-old mystery. The next step is to test it scientifically in people who develop these headaches, so stay tuned.”
They hope to begin these studies in a few months.
But Professor Corder, who has studied the possible health benefits of wine, suspects other ingredients are worth exploring as headache triggers:
Pectinases accelerate the release of anthocyanins, which speeds up wine production by releasing color, without the slow maceration processes of traditional wine production, but they are methyl hydrolases and a by-product of their activity is the production of methanol.
Dimethyl dicarbonate is used as a preservative for cheaper wines, especially those shipped in large containers for bottling in the UK, but it also breaks down to create methanol.
Drinking too much, too fast, or drinking to get drunk can have serious short- and long-term health consequences.
Regularly drinking more than 14 units a week – about six pints of medium-strength beer or 10 small glasses of low-alcohol wine, the type of alcohol doesn’t matter – can damage the liver and cause other health problems, including strokes and heart disease.
Alcohol consumption is also linked to different types of cancer.