What are sulfites and why do they divide the world of natural wine?
Sulfites in wine: it’s a topic that makes more noise than a popping cork. A dangerous chemical preservative to some, an indispensable ally for the winemaker to others—the reality is a bit more nuanced than the debate on social media. Here is what it really is.
First off: what are sulfites?
Sulfur dioxide (SO2)—its real name—has been used in winemaking for centuries. The Romans were already burning sulfur in their amphorae to sanitize them. Today, it serves two specific purposes: protecting wine from oxidation and killing off unwanted bacteria and yeasts that could alter the taste.
What many people don't know: wine naturally produces small amounts of sulfites during fermentation. Yes, even wine "without added sulfites" contains them—at tiny levels, around 10 mg/L. It is biochemistry, not the winemaker, that is responsible for this.
The mandatory label "contains sulfites" applies starting at 10 mg/L—which, in practice, concerns almost all wines.
How much is added, and in which wines?
European regulations set maximum levels based on the type of wine:
- Conventional red wine: up to 150 mg/L
- Conventional white and rosé wine: up to 200 mg/L
- Mellow white wine: up to 300 mg/L, or even more for sweet wines
- Organic wine: caps reduced by 30 to 50 mg/L compared to conventional
- Wine "without added sulfites": no additions, but residual natural presence
The sweeter or whiter the wine, the more sensitive it is to oxidation and bacteria—hence why, historically, there has been a tendency to protect it with SO2. Red wines, rich in naturally antioxidant tannins, generally need less.
Why the natural wine world says no
The natural wine movement was built in part on a refusal: that of interventionism, both in the vineyard and in the cellar. Sulfites, even at legal doses, are perceived as a crutch that masks the flaws of slapdash winemaking rather than showcasing the terroir.
The argument from natural winemakers: if your grapes are healthy, your harvest impeccable, and your cellar hygiene irreproachable, you don't need SO2 to stabilize your wine. Sulfur, in a way, allows for "cheating"—compensating for questionable viticultural choices with chemistry.
There is also a philosophy of risk. Vinifying without sulfur means accepting that wine is alive—that it evolves, sometimes unexpectedly, and that it is more fragile when exposed to heat or poor transport conditions. It is a gamble on the living rather than sealing it under a glass cloche.
And the morning-after headaches?
We often hear: "red wine gives me headaches, it's because of the sulfites." It's a popular explanation. It's convenient. It's also likely false.
The real culprits behind post-drink headaches are likely elsewhere: biogenic amines (histamine, tyramine), the alcohol itself and its effects on hydration, or tannins for some sensitive individuals. Sulfites themselves can cause genuine allergic reactions—but these primarily concern asthmatics, and manifest as breathing difficulties rather than headaches.
By way of comparison: dried fruits (apricots, raisins) often contain 5 to 10 times more sulfites than a glass of red wine. If sulfites were truly the problem, happy hours with cashews and dried apricots would be a neurological carnage.
In summary — what you need to remember
Sulfites are neither the poison some people raise alarms about, nor the magic ingredient others defend. They are a tool. Like all tools, the question is not "is it in the box?" but "why are we using it and in what quantity?"
A winemaker who works their soil using organic or biodynamic methods, who harvests by hand, who vinifies with care—and who adds a small dose of SO2 at bottling to protect the wine during transit—is making a defensible technical choice.
A winemaker who adds sulfur at every stage to compensate for industrial practices in the vineyard, that is another story.
At LET IT BiB, we work with winemakers who have made strong choices—certified organic, in conversion, biodynamic, or natural wine. The sulfite level is part of that. You can find the characteristics of each wine directly on the product pages.