Recently at a wine dinner, one of my table-mates asked, “Why does cheap wine give me a headache?” I have made a point of avoiding cheap wine for quite a long time, so I didn’t have an answer at hand, but the question intrigued me. Case accepted.
As any modern day sleuth would, I began my investigation on the Internet. After wading through multiple postings (often accompanied by an “I’m not a doctor” disclaimer), the likely answer seemed to be sugar, but I didn’t find any data to support this conclusion. Then, when working on something else, I came across an article talking about residual sugar levels in mass market wine and I became convinced.
The biochemistry that makes wine possible is the conversion of sugar into alcohol (and carbon dioxide) by yeast. This process normally continues until the sugar is used up and the yeast has nothing left to work on. The resulting wine will typically have residual sugar levels under 3 g/L (grams per liter).
When setting out to make a less expensive wine, it is clearly to the benefit of the producer to maximize the yield of the grape vines. This, however, also increases the chances that the resulting wine will be thin and acidic– something that will not sell well, even at a low price. By adding sugar after fermentation, a producer can balance out the wine and give it more body, making it a more enjoyable quaff.
The proof that this is going on is in the residual sugar levels of mass-produced wines, which often run around 12 to 15 g/L. This works out to more sugar in each glass of cheap less expensive wine than in an entire bottle of wine without added sugar. Some popular wines have residual sugar levels exceeding 50 g/L (or about as much sugar in each mouthful as in a bottle of quality wine)!
Why does this cause a headache? The commonly accepted explanation is dehydration. In processing both alcohol and sugar, the body uses water, which can lead to dehydration and cause a headache. Either one can do it by itself, but put them together and the odds go up quickly.
Not all less expensive wines have added sugar. But if you find that a moderate quantity of some wine gives you a headache that you don’t normally get, you might want to look into the residual sugar levels (these are often published on winery websites). Oh, and drink more water. Your doctor would probably tell you to anyway.