Q: How much sugar is in a glass of wine?—Zak, Bend, Ore.
A: When it comes to wine and health, few subjects are as clouded with misconceptions as sugar. While keeping tabs on sugar intake is good for everyone (especially people with diabetes or those looking to lose weight), it’s important to make a few things clear.
Most wine is dry, meaning it contains very little sugar at all. As grapes ripen, their sugar content increases until harvest, when they contain high amounts of the simple sugars glucose and fructose. In some places, winemakers can chaptalize, adding sucrose before or during fermentation to complement the grapes’ natural sugars. Chaptalization boosts alcohol levels in areas where grapes struggle to ripen, but it doesn’t make the finished wine sweet.
During fermentation, yeasts convert most of the sugar in the grape must into ethyl alcohol. Any sweetness left in the wine after this process is called residual sugar. Producers sometimes add a little sugar after fermentation to boost mouthfeel and make the wine more palatable, but this isn’t done in high-quality winemaking. Dry table wines typically contain less than 10 grams per liter of residual sugar, which means a 5-ounce glass would contain 1–2 grams at most, and often much less.
Of course, there are many off-dry, sweet and fortified wines that do contain sugar in significant amounts, sometimes up to 200 grams per liter or more. Wines are typically considered sweet if they contain more than 30 grams per liter, with off-dry wines falling between 10 and 30 grams per liter. To make fortified wines, such as Port, neutral spirit is added to stop fermentation before all of the grape sugar can be converted to alcohol, leaving quite a bit of sugar in the finished wine. Certain dessert wines, such as Sauternes, simply contain so much sugar before fermentation that the yeasts aren’t able to convert all of it to alcohol. And many sparkling wines contain sugar in the form of the dosage, the small amount of wine, usually mixed with sugar, added to the bottle after the secondary fermentation that determines the wine’s final sweetness.
If dry wines contain so little sugar, where do their calories come from? Dry wine drinkers counting their vinous calories have only alcohol itself to blame. Ethanol, like all alcohols, produces 7 calories of energy per gram when metabolized by the body. This amounts to around 120 calories in a standard 5-ounce glass of wine at 12 percent alcohol. For comparison, carbohydrates (including all sugars) produce 4 calories per gram, while fats produce a whopping 9 calories per gram.
To learn more about sugar, wine and your health, read our in-depth Wine & Wellness article. As always, talk to your doctor about incorporating wine—whether bone-dry or sweet as nectar—into a healthy lifestyle.—Kenny Martin
