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Explainer Science

Wine Sulfites and Why People Argue About Them

Used as a preservative since ancient times, sulfur has become contentious

David W. Brown By November 3, 2021
illustration of wine being surrounded by different tools and materials
Illustration by Dante Terzigni

All wine bottled in the United States with a sulfite level greater than 10 milligrams per liter must include the words CONTAINS SULFITES on the label, leaving buyers to wonder whether sulfites are dangerous.

Perhaps the most prominent winemaker in the United States to forego all chemical additives in his wine, including sulfites, is Tony Coturri of Coturri Winery in Sonoma County, California. 

“The bag that sulfur comes in says it’s poison,” he says. “I think that putting sulfites in wine takes away the terroir. Takes away the individual quality of it. While you could still have pretty good grapes, they’re going to be losing that edge that the grower’s been working so hard to get.”

Poison? Terroir killer? Yet the use of sulfur compounds in winemaking goes back to at least the ancient Greeks. Sulfur was abundant in the volcanic Mediterranean region, possibly leading to its discovery as a preserving agent. In recent times, more than any other wine intervention, the addition of sulfites generates division, with some people seeing them as an ancient preservative that’s part of wine history and culture, while a growing group of natural winemakers see them as just another chemical that needs to be abandoned.

How sulfites are used

Sulfites, in their varying compound forms, manifest in winemaking in three ways: They are a natural byproduct of the fermentation process, they are used to sanitize winemaking equipment and space, and they are added to wine to kill rogue microbes and prevent oxidation. 

Sulfites are inorganic salts with sulfur as a constituent element. Both sodium metabisulfite and potassium metabisulfite may be used by winemakers to clean equipment, and the latter, which comes generally as a powder or tablet, can be used as a preservative in wine itself. Once added to wine, potassium metabisulfite forms sulfur dioxide, SO2, a disinfectant and antioxidant. 

The term “sulfite” is an industry shorthand for this SO2.

Winemaker Keith Wallace, the founder of the Wine School of Philadelphia and a board member of the National Wine School, says that sulfites get a bad rap. He says that crushed grapes, or raw juice, can be spoiled by bacteria and yeast.

“We use sulfites because rule number one in making wine is not to kill people. Rule number two is to make something delicious. These two things have to happen,” he says. “It is actually an incredible, naturally occurring food-safe preservative. It’s the safest preservative we have.”

Some of the finest, most expensive wines use sulfites in the winemaking process, says Haley Moore, a San Francisco sommelier and founder of Acquire, a hospitality company. “Even Domaine de la Romanée-Conti, which uses almost no intervention and is for all intents and purposes a natural wine, uses SO2 in some of the most expensive and highly sought-after wines in the world.”

There is no evidence that sulfites are poisonous when used as intended. Indeed, the use of sulfites, she says, makes wine stable. “You’re talking about ageability, you’re talking about no potential for secondary fermentation, no potential for bacteria or any other funky things to take over.” Prized Bordeaux and Burgundies use sulfites to minimize unpredictability. “You can’t take that risk when you’re charging thousands of dollars a bottle — it’s not possible.”

That is part of the problem, says Coturri. 

Are sulfites necessary?

“When you talk to young winemakers — even in natural wines — and ask why they add sulfur to their wines, they say it’s because they have so much money invested, that they can’t take the chance,” says Coturri. “That’s the beginning of the end right there.”

Many natural winegrowers think that SO2 takes something away from the fruit expression in the wine, that in some way mutes the aromas.

Coturri thinks that big companies rely on SO2 because their fruit isn’t always top quality. “When they take grapes from many different vineyards and kind of put them together, they don’t know what the grower did, or whether there is mildew or anything.” They consider sulfite to be a literal insurance policy, he says. “If you start with good grapes, you don’t need an insurance policy.”

Jahdé Marley, a New York City-based sommelier, agrees. “It’s all about allowing the grapes to speak for themselves,” she says. “It’s about responsible, sustainable farming, and what skilled hands can do in the vineyard. If you are putting in all that labor to grow or source the best quality raw material, why would you want to cover that up?”

She adds, “If you are making tomato sauce from delicious, vine-ripened tomatoes, would you dump a whole bunch of sugar and salt in there?”

Consumer misconceptions

For their part, U.S. consumers of wine are understandably leery of sulfites because the CONTAINS SULFITES labeling seems similar to the Surgeon General’s warning on packs of cigarettes.

This has led to the misconception on the part of consumers that sulfites cause wine headaches. 

“If you get a headache, you look at the bottle and say, ‘What’s that thing that they’re warning me against?’” says Wallace. “It always says sulfites on bottles in this country, so they blame that — and it makes perfect sense. That’s not the consumer’s fault for making that assumption.”

“There are so many things that should be warned about in wine, like whether or not they are vegetarian or vegan. Those things matter. Sulfites do not.”

The sulfite warning went onto wine labels in 1987 following an earlier sulfite ban by the U.S. Food and Drug Administration on fresh, raw fruits and vegetables; thirteen deaths from severe allergic reactions were linked to sulfites over a four-year period. U.S. winemakers are allowed to add sulfites up to 350 parts per million but, in practice, winemakers use much lower levels. Typically, a red wine would contain around 60 ppm to 80 ppm, and a white perhaps up to 100 ppm, with sweet wines having slightly higher levels. 

In any case, other packaged foods, such as dried fruits and canned goods, contain much higher levels of sulfites. The drinker at the table who forgoes the wine because of a “sulfite allergy” but then reaches for the bread will ingest more sulfites than if he or she drank the entire bottle.

 The drinker at the table who forgoes the wine because of a “sulfite allergy” but then reaches for the bread will ingest more sulfites than if he or she drank the entire bottle.

Not convinced

In his 42nd year of winemaking in both California and Texas, Coturri says he has never added sulfites to his wine. He says that he has sulfite-free wines that are holding together even 20 years after bottling.

“It’s not impossible. It takes a little more care,” he says. “A lot of people say, ‘Sure, Tony Coturri can do that because he figured out the secret to doing it.’ I don’t have a secret! I’ll tell anybody that wants to listen how to do it, but it needs extra work. You’ve got to be mindful of what you’re doing.”

He says, “We’re stewards of food. If you’re in the restaurant business, if you’re a baker, if you make anything that human beings have to ingest, it better be pure — period. It is our sacred responsibility to the public.”

Andrew Lohse, a sommelier in New York City, says many of the perceived downsides of sulfites in winemaking are misconceptions, “whereas the upside of SO2 is very obvious. It’s about preserving the wine and keeping it stable in the bottle and transferrable, which has been one of the main problems in winemaking for thousands of years.” 

He also says that it’s easier to make sulfite-free natural wine in some places than others. 

“In Bordeaux, it’s very difficult to do that. You have a moisture problem that you need to contend with, and you’re making massive amounts of wine at any given time. You have to systematize it,” says Lohse. “But if you have two hectares in the Oregon wilderness, you’re not making that much wine and it’s easier to be a little bit more hands off.”

Coturri is skeptical of claims that any winery needs to add sulfites to its wine. As for the righteousness of his cause, Coturri appeals to the ultimate authority.

“I’m not necessarily religious,” he says, “but the first miracle of Jesus Christ was turning water into wine. Ask the question: Were there sulfites in it? Of course not!”