What are Sulfites?: A Debated Addition to Natural Wine

Posted by Gregory Babcock on

You’ve probably spotted the phrase “contains sulfites” after picking up a bottle of wine, but probably not given it too much thought. At worst, some might even see it as a mark against the wine they’re about to pour, bracing for an expected—almost inevitable—headache.

So much remains mysterious or confusing about the winemaking process, but few things are as misunderstood as sulfites. Even with a complicated reputation among wine drinkers, there’s a lot more to sulfites (and their part in the winemaking process) than a line of text on the back of a label. With plenty of myths to debunk and terms to clarify, sulfites remain one of the most controversial topics in wine today—especially when it comes to their role in the natural wine movement.

What are Sulfites?

Sulfites are a chemical compound (otherwise known as sulfur dioxide or SO2). It’s a preservative and antioxidant that’s found in both wine and food—so while you’ll likely find sulfites in nearly all the bottles at your local shop, you’ll also find sulfites within other fermented or preserved foods, including bacon, butter, pickles, canned fish and dried fruits.

Will Sulfites Give Me a Headache?

Ok, let’s get to the reason you probably clicked on this article to begin with. This is one of the biggest misconceptions in wine, even if there’s elements of truth within the myth.

The short answer is, (likely) no. Sulfites will not give you or cause a wine headache. (To be clear, most hangover headaches and nausea are a result of overindulgence-induced dehydration or even histamines—but that’s another post all on its own).

That said, there is a segment of the population—roughly under 1 percent according to the FDA—that are deemed “sulfite sensitive.” If you suffer from severe asthma or lack the enzymes to process sulfite in your body, a sulfite intolerance will result in serious allergy symptoms, including shortness of breath or hives. While rare, the possibility for an allergic reaction is why wines include the warning “contains sulfites.”

While we’re not medical experts (and we’re not claiming to be), the odds are that if a severe reaction doesn’t manifest itself within 30 minutes of sulfite exposure, you’re likely not someone within the “sulfite sensitive” section of the population.

How Much Sulfites Are in Wine?

Broadly speaking, wines need to include the term “contains sulfites” if they contain 10 ppm (parts per million) of SO2, or greater, in the final product. For some context, dried fruit can have as high as 3500 ppm of sulfites. As noted in Wine Folly, red wines will average anywhere from 50-350 ppm, and whites will be slightly higher. By United States law, sulfites can not exceed 350 ppm in a bottle of wine.

According to Bon Appétit, the requirement to denote sulfites on wine bottles was part of a push in the 1970s and 80s to discourage alcohol consumption, culminating in a 1987 regulatory law. This anti-alcohol sentiment is why you’ll see sulfites boldly denoted on wine, but might not see it as explicitly (compared to a wine bottle) on containers of preserved food—even though it might have more than 10 times the amount of sulfites.

constant crush back label

How Are Sulfites Used in the Winemaking Process?

Primarily sulfites are used as a way to prevent oxidation or spoilage of wine. They can be added during the winemaking process or at the bottling stage to ensure the stability of the wine before it’s sent off to stores, sits on a shelf and—inevitably—ends up poured into a glass.

Historically, preservatives have always been a part of the winemaking process, going all the way back to the Roman times. While the Romans might have added resin or sea water to their amphora to prevent (or mask) spoilage, they also burned sulfur candles in wine vessels for the same reason. The modern use of sulfur in winemaking began in the early-1900s.


Conventional or mass-production winemakers can add sulfur at various stages, ranging from the moment the grapes are brought in from the vineyard, during the racking process or all the way up until the wines are poured into their finished bottles.

Sulfites and the Natural Wine Movement

To cut right to the core, winemakers within the natural wine movement are focused (among other things) on altering the wine grapes as little as possible as they travel from vine to bottle. This is what makes sulfites a touchy subject, since their appearance in wine—even natural wines—can often occur even if a winemaker is a strict non-interventionist.

Sulfites appearing in your latest bottle of wine can be a result of one of two types of sulfites. “Added sulfites” are just like they sound; these are the aforementioned sulfites that are intentionally added by the winemaker to prevent oxidation, avoid spoilage and even stop the wine from becoming vinegar. Added sulfites are practically a fact of life in “traditional” or “conventional” winemaking, and will almost always appear at some point in the process.

“Naturally-occuring sulfites” are where things get a little trickier. While we’ve already discussed how sulfur can stabilize wine and keep unwanted bacteria and spoilage agents out, sulfites also occur organically as part of the fermentation process. Generally these wouldn’t be enough to act as a long-term preservative all on their own (hence the practice of adding external sulfites to help keep what’s in the bottle shelf- and cellar-stable).

assortment of low sulfite natural wines

In a natural wine context—when the focus is keeping any and all additives or preservatives out of the wine—it can seem jarring to read “contains sulfites” on a bottle that should, in theory, be “natural” (and, by extension, sulfite-free). The ironic thing is, a wine can remain completely untouched from vine to bottle, and still contain sulfites; like most things in the natural wine world, there’s no single definition of what “natural wine” is or can be—sulfite inclusion can help contribute to this.

For most natural winemakers, the reality is that their wines will likely contain sulfites—though most are going to fall into that “naturally-occurring” camp. For some producers, they’ll choose to add sulfur at the bottling phase (but not during the winemaking process) to, for lack of a better term, “lock in” their wine’s profile and flavor. Given that most natural winemakers—even ones who add sulfur at bottling—don’t add other preservatives to their wine and rely on native yeasts to actually drive the fermentation process, adding sulfur at bottling also helps the wine from becoming unstable, oxidized and mousy (aka: undrinkable). This sulfur addition—however small—also makes it easier for the wine to ship (usually across continents) without leading to spoilage by the time it gets to its final destination.

Even though the natural wine scene includes several producers who add small amounts of sulfur at bottling, there’s another contingent who are far more zealous about additives. This is where the Zero/Zero movement comes in.

What is Zero/Zero Wine?

Zero/Zero (also stylized as 0/0 or 00) wines are wines that have nothing added and nothing taken out. The designation is meant to suggest that the winemaker has effectively pressed the grapes and let the juice ferment naturally into wine—which is unfined, unfiltered and wholly unaltered in any way.

Adherents to a zero/zero philosophy will not add any sulfites to the wine—during the winemaking process or at bottling. Usually wines that emphasize this approach will also include the words sans soufre (which, in French, translates to “without sulfur”). Even still, as we’ve mentioned already, these wines may still contain naturally-occuring sulfites, just in very trace amounts.

To be completely direct: There is no such thing as a truly “zero sulfite wine.” This is why, if you’re someone looking for a zero/zero wine or a wine with as little sulfites as possible, it’s best to look for bottles that say “no added sulfites” or “low sulfites.” These terms get at the spirit of what the zero/zero movement is trying to do, while using a slightly more accurate nomenclature.

Sulfites and Brutal Wine

brutal wine zero sulfites

One of the most exciting (and, in some ways, mysterious) projects in natural wine centers around “Brutal” wine. Beginning in Spain and ultimately finding fans the world over, Brutal wine is effectively built upon a zero/zero wine philosophy, focused entirely on making wine with no intervention whatsoever.

Since its beginnings, the wines have always been experimental, which is why virtually any winemaker can produce their take on Brutal. Regardless of where the wine is made or what grapes are used, the important thing is that there are no added sulfites. This is why—no matter who is making that version of Brutal—that there will likely be an image of a Grim Reaper slicing a molecule of SO2 on the front of the bottle.

If you’re looking for something unique or one-of-a-kind (not to mention something that’s truly epitomizing what zero/zero can be), Brutal wines are your best bet. You can read more on the history behind the Brutal movement right here on the No MOG Blog.

A Quick Note on Sulfites vs. Sulfates

Not seen on wine bottles but likely seen on cleaning products, you’ve probably heard of sulfates. Sulfites and sulfates are both sulfur-based compounds, but sulfates are salts of sulfuric acid, and is used as a degreaser or detergent that helps bind oil to water (a common chemical compound in this context is sodium lauryl sulfate). While sulfates aren’t common in winemaking, they can be used in beer—calcium sulfate specifically—to even out minerality issues in the brewing process.

So, Are Sulfites Good or Bad?

Ultimately, this is up to the consumer buying the bottle, but generally speaking a small addition of sulfites has been in practice for decades—even in natural wine circles. While the focus of natural wine producers and consumers continues to be centered on low-intervention, the realities of shipping wine globally or simply storing bottles for more than a few weeks necessitates the use of some sulfur—if only at the bottling phase.

Alice Feiring, author of Naked Wines: Letting Grapes Do What Comes Naturally and one of the world’s most prolific experts and advocates for natural wine, defines natural wine as, “Nothing added, nothing taken away. Maybe a smidge of sulfur.” Frankly, we couldn’t put it better ourselves.

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