Why does Wine contain Sulfites and How toxic is Sulfite when added to Wine?

Sulfites, not to be confused with sulfates, are a family of chemical salts derived from sulfur dioxide (SO2). They are formed during the fermentation of wine from sulfur compounds naturally present in the grapes, so a certain small amount is indeed natural and unavoidable.

In addition, sulfites (or sulfur dioxide gas from burning sulfur) have been added to wines for thousands of years to protect them against oxidation and discoloration.

Moreover, sulfites can kill harmful bacteria and wild yeast cells in the grape pressings so that the “tame” fermenting organisms can get a biologically clean start. Without the preservative effect of added sulfites, wines would not be drinkable after one or two years, which may be little problem for a wine that is best drunk young, such as a Beaujolais, but would be a tragedy for a slow-aging Bordeaux.

About one person in a hundred is sensitive to sulfites, which can even bring on an asthma attack in asthmatics. Sensitive individuals should avoid foods that contain any of the following: sulfur dioxide, potassium bisulfite, potassium metabisulfite, sodium bisulfite, sodium metabisulfite, and sodium sulfite. Note that, except for sulfur dioxide itself, the tip-off is the suffix -ite in the chemical name.

As with all ingested substances, it’s not a simple matter of good and bad. Any chemical is inherently neither “safe” nor “dangerous.” It’s all a matter of amount. The legal limit of sulfites in wine in the United States is 35o parts per million (ppm), although most wines with added sulfites contain only 25 to 150 ppm. According to federal law, if a wine contains 10 ppm or more of sulfites, the label must state that it “contains sulfites.”

With your wine storekeeper’s assistance, look for an FDA approved “No sulfites added” notice on the labels of some bottles. Your husband can then try them and see if the small amount of natural sulfite is enough to give him a reaction.

And by the way, anyone who says that something “smells like sulfur” probably never took a chemistry course. The solid element sulfur, known biblically as brimstone, is perfectly odorless, but many of its compounds are evil-smelling. Sulfur dioxide is the smell of burning sulfur.