(VinePair) - “Contains sulfites” is a fairly off-putting statement on a bottle of wine that you hope to enjoy with a meal, gift to a friend, or share with a loved one. Um, you mean, there’s chemicals in here? So, are they bad for me—is that why wine sometimes gives me headaches? And can wine be made without these sulfites?

First of all, it’s important to point out that what’s on the label is simply letting you know that naturally occurring sulfites occur, in every single bottle of wine. This is a separate matter from the question of added sulfur, which is actually more relevant in terms of how a wine tastes and how it makes you feel. But we’ll get to that.

Firstly, what are sulfites? The term refers generally to sulfur dioxide (SO2). The reason all wine labels in the U.S. contain this ominous warning is that SO2 is a natural byproduct of fermentation—therefore, virtually all wine contains it. Where it gets tricky (and potentially interesting, if you like to nerd out on wine, which you must because why else would you be reading this?) is the question of added sulfur as a winemaking technique.

Sulfur has been added to wine for a long time; the naturalist philosopher Pliny even wrote about winemakers using the pungent, “pale, yellow, brittle” substance, according to Jancis Robinson’s authoritative Oxford Companion to Wine. Essentially, sulfur ensures the stability of wine by killing off active yeast and bacteria, and protecting wine from oxygen, which can transform it in numerous ways. Adding sulfur is helpful in numerous scenarios: when you’ve just harvested a bunch of grapes and it’s really hot and you don’t want them to ferment, for example; another common reason is that much wine is exported, and sulfur prevents it from re-fermenting during shipment.

But the thing about sulfur is that it can prevent wine from showing its nuances. Sulfur-laden wine is predictable—which can be a good thing. But when you try low-sulfur wine, or sulfur-free wine, the juice is surprisingly alive.