Here, wine expert, James Kornacki, creator of the Üllo Wine Purifier sheds light on the topic by seperating the myths from the facts surrounding sulfites.

What are sulfites?

Sulfur dioxide, also known as sulfites, is a compound formed from sulfur and oxygen. Sulfites exist naturally in wine in low levels - less than 5 ppm (parts per million) - because of the fermentation process.

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Most winemakers will also add additional sulfites (up to 350 ppm) as a preservative. Sulfites are added to wine at three stages of winemaking, with the majority added just before bottling, to kill any microorganisms that would lead to spoilage. These sulfites are added as the fully synthetic chemical sodium metabisulfite – a highly-regulated food additive that is banned entirely as a preservative for meat or produce.

Confusion has surrounded the topic of suliftes for decades, ever since they became regulated in the late 1980s in the US. This required wine makers to add the 'contains sulfites' warning labels to the back of every bottle, a practice now mandated worldwide.

Often it’s these two words that are the source of confusion and misunderstanding. You’ve probably heard that drinking red wine gives you a headache due to the amount of sulfites added, and perhaps you’ve been advised to stick to white wine or organic wines, or to avoid wine altogether.

Sulphite allergies are common

Fact. James comments: “One in 50 people are sensitive to sulfites and suffer from unpleasant symptoms including respiratory irritation, especially among asthma sufferers. However, severe allergic reactions to sulfites are rare but can include swelling in the face, throat or mouth, abdominal pain, nausea and vomiting. It’s these allergic reactions that first triggered the regulation of sulfites.”

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Red wine contains more sulfites than white wine

Myth. It’s white wine that is higher in sulfites. James explains: “White wines on average are sweeter than reds. Sugar is food for bacteria, so sweeter wines then require higher levels of sulfites to sterilise the wine.

“Sulfites also bind to sugars, reducing their efficacy, so that even higher relative doses of these chemicals must be used in sweeter wines. Wine drinkers who report headaches or other unwanted effects from drinking only red wine may need to look past the sulfites to find the culprit.

"Biogenic amine compounds, such as tyramine and histamine, may be responsible along with the thousands of polyphenolic 'tannin' compounds of unknown structures, functions, and identities. Ironically, these are also the compounds believed to elicit red wine’s cardioprotective and even life-extending effects.”

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Consumption of sulfites is generally harmless

Fact. “Consumption of sulfites is generally harmless to those who consume wine, unless you have a sulfite intolerance which will mean your body reacts to them.

“However the amount of sulfites added to wine is highly regulated around the world and is known to be relatively safe in the quantities allowed. However, these chemicals are added to kill microorganism, so by definition, they are designed to be toxic,” explains James.

Organic or bio-dynamic wines are sulfite free

Myth. To be certified organic, a wine must not contain added sulfites.

“However, sulfites are produced naturally during the fermentation process as a by-product of yeast metabolism,” says James. “Even though no sulfites are added, organic wine may contain a certain number of sulfites, although the levels found in these wines would be generally considered safe.

"Unfortunately, wines made without sulfites cannot be aged and either require refrigeration or the addition of an alternative preservative, often potassium sorbate. Because sulfites react with chemicals in wine susceptible to oxidation - a good thing - wine made without sulfites will maintain fruit juice flavours of these unreacted, volatile organic compounds.”

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Most wines have sulfites in them

Fact. Very few wines are made without added sulfites, James says, as the winemakers have very little control over the storage conditions of the wine once it leaves the winery until its consumed. “Sulfites are a near requirement in order to guarantee that the bottle of wine you open will be fresh and taste as the winemaker intended.

“Sulfites are the reason we can enjoy wine from all over the world, and the reason we can collect wines. Sulfites are not evil; they are indispensable to winemaking. Their job as a preservative is just very much over the moment you pull the cork.”