Sulfite, also known as sulfur dioxide, is a preservative that both occurs naturally and is added to wine. Sulfites are produced by the yeast added to wine for fermentation, but sulfites are often added to boost the preservation of wines. In people who lack the enzyme to break down sulfites, they can at high levels produce some unpleasant side effects.
Although wineries have been using sulfites to preserve wine for 200 years, even the ancient Romans and Greeks used sulfites to sterilize. Only since the late 20th century, however, have we begun to connect sulfites to their health side effects.
The most common side effect of sulfites in wine is an allergic reaction, or an aversion to excess sulfites. Allergic reactions in those who lack the enzyme to break down sulfite are commonly a rash or tingling and swelling. According to the FDA, symptoms in asthmatic patients tend to be more severe.
Misconceptions About 'Sulfite' Headaches
A long-standing idea has persisted that sulfites cause headaches for some wine drinkers. However, no studies prove the link between sulfites and headaches. Furthermore, sulfites are present in a number of other foods, such as dried fruit, where they are not linked to headaches.
Problematic side effects caused by sulfites are generally found in those with sulfite allergies and, especially, asthma. Headaches associated with wine, but not sulfites, seem to be associated with the histamines, tannins or grape skins.
If sulfites are a problem for you, it should be noted that white wines generally have more sulfites than reds. Wines made from organic grapes in the United States generally have fewer sulfites and, by law, cannot contain added sulfites.