Let’s try a little experiment : eat some orange coloured dried apricots, wait quarter of an hour, assess how you’re feeling. All good? No sudden onset headache? Marvellous. We’ve just proved that sulphur isn’t responsible for RWH.
RWH is an official syndrome where an estimated 1% of the population experience a headache about 15 minutes after drinking wine to which they are sensitive (it’s like a really speedy onset handover!). People often blame a sensitivity to sulphites. Research by Dr Andrew Waterhouse has proved that in fact sulphites aren’t to blame although the cause is still being debated; histamines or tannins might be the culprits behind RWH.
Sulphites are non-metallic, naturally occurring compounds that have been used in wine and fruit preservation since ancient times. Today they are added to wine, usually in the form of sulphur dioxide (SO2), predominantly as a preservative and anti-oxidant. If the wine is produced and stored properly, minimal quantities are required (measured in parts per million ‘ppm’) but if there weren’t any sulphites at all added to wine it would last less than a year and risk turning into vinegar.
Sulphites in tiny amounts are a natural bi-product of the fermentation process. The rationale behind adding additional ‘free’ sulphur at the fermentation stage is for these molecules to react with oxygen molecules in the wine before the oxygen can ‘oxidize’ the wine and turn it to vinegar. In addition, the added sulphur is anti-bacterial and neutralizes any unwanted bacteria and yeasts. When the free sulphur combines with another molecule it undergoes a chemical transformation and becomes ‘bound’ which means that it can’t react with another molecule, and ergo cannot trigger an allergic reaction.
Some winemakers leave sufficient free sulphur in their wine at the bottling stage to continue to ‘track down’ any free oxygen, sugars and bacteria over the coming months to ensure the wine remains in good condition. They calculate the exact quantity required to react with expected oxygen levels and still leave the desired amount of free sulphur roaming around to be on the safe side. This free sulphur can cause allergic reactions in sulphur sensitive people.
White wines contain more sulphites than reds, and sweet wines will have the highest quantities in order to stop the breakdown of sugar in the wine. The maximum levels of sulfur dioxide in the EU are 160 ppm for red wine, 210 ppm for white wine and 400 ppm for sweet wines and similar levels apply in the US, Australia and around the world. Excelsior wines have a sulphur level of c. 60ppm for red wine and 100ppm for white wine.
Sulphur is found naturally in a wide variety of foods and added to others as a preservative, such as the dried apricots mentioned at the beginning of this post which would contain about ten times more sulphites than wine. It is readily digested by the body and is in fact, in appropriate quantities, an essential micronutrient since it forms a component of fats, body fluids and skeletal minerals.
So many wine labels say ‘contains sulphites’ but that’s not the whole story since all wine contains some sulphites and the amount can vary dramatically depending on the added sulphites and the quality of the wine.
Ironically, just as interest in the sulphite content of wine has increased, technology available to winemaker means levels of sulphur in wine are at an all time low.
Article: Do Sulfites Give Me Headaches?
Good Wine Online: Low Sulphites Explained
Bordeaux Undiscovered: Why do some wines give us headaches?
De Reuck Wines: Do you get headaches from drinking certain wines? Why?
This Day in Wine: Top 6 Facts about Preservatives in Wine