Thursday, January 14, 2010


We’ve all seen it. You’re at a dinner party, or a wine-tasting, and suddenly, someone’s face turns red. Is it embarrassment? No, it’s redder than a blush. Has your charm turned them on? You wish. Could it be a reaction to, yikes, the wine? If it is the wine, what’s in the wine that makes someone’s face go red?

For some people, it’s the alcohol. These folks most likely have a deficiency in (wait for it) acetaldehyde dehydrogenase, an important enzyme in metabolising alcohol. The result is the accumulation of acetaldehyde, which shows up as a reddening in the face, neck, and shoulders. Other symptoms include nausea, headaches, light-headedness, an increased pulse, drowsiness, and occasional skin swelling and itchiness.  [UPDATE, Jan 21:  Wine Spectator reports there's a possible cure for this enzyme deficiency.]

But maybe it's not the alcohol. It might also be sulphites, or histamines, or other additives.

Fermentation produces sulphur dioxide naturally, as the yeast converts grape sugars to alcohol. Many producers add more sulphur dioxide (or sulphites) as a preservative. For people who lack the enzyme to process sulphites, an allergic (asthmatic) reaction, including flushing, may result. If you’re trying to avoid sulphites, some biodynamic and organic winemakers go out of their way to keep sulphite levels down, and say so on their labels. Vintages also does a good job of identifying these wines in their New Releases.

Bacteria and yeast often generate histamines during fermentation, and alcohol tends to amplify the effects of histamines. For those people sensitive to histamines, face-flushing, a runny or stuffy nose, itchy and runny eyes, or worsening of asthma symptoms, as well as headaches, may result from drinking wines with an elevated level of histamines. The same bacteria that generate histamines may also cause wines to spoil. Researchers at Bordeaux University (where else?) are currently working on a project to eliminate the bacteria (and resulting histamines) produced as part of the fermentation process. Good news for allergy sufferers and the rest of us who don’t want our wines to go off.

Winemakers may also use allergenic substances in fining. (Fining is the clarification and stabilisation of wine by removing microscopic proteins that may cloud the wine, or removing tannins that make the wine more astringent or bitter than the winemaker wants, or removing unwanted aromas.) Organic substances, such as egg whites, milk, fish bladders all have been used (but not exclusively) in fining. Very little of these substances remain in the wine but highly allergenic people may still have a reaction. And, obviously, vegans are not keen on wines that have used these substances.

We may think that those people who have a reaction to wine (whether it’s because of alcohol, sulphites, histamines, or other substances) are unlucky. But another way to look at it is that they have a built-in moderator. They avoid over-indulging and, the morning after, don’t have to look for a cure!

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