Sulfites exist in nature and are also naturally contained in or even added to preserve a very long list of many common foods, including wine, cheese, yogurt and other processed dairy, bread and baked goods, tortillas, dried fruits, dried spices, shellfish, dried seafood, canned, bottled, or frozen fruits and juices, jams and jellies, tofu and other soy protein products, packaged pasta or rice mixes, etc.. The human body actually produces about 1 gram of sulfites daily through normal metabolism.
About 1% of the general population and about 5% of asthma sufferers may react to sulfites. Symptoms commonly include restricted breathing ability to varying degrees from mild to severe, even life-threatening, especially in asthmatics prescribed to steroids. Skin rashes, hives, itching and nausea are relatively rare symptoms for sulfite allergy. Reactions depend on both the sensitivity of the individual and the level of sulfites ingested. Headaches are not a symptom of sulfite reaction, although this is a common folk tale (see next section).
Foods may legally contain sulfites at levels ranging from 6 to 6,000 parts per million. The legal maximum for wine is 350 ppm, but the average content in premium wine is under 40 ppm. White wines are generally higher in sulfites than red wines. Inexpensive wines generally have higher sulfur content than expensive wines. There are no wines that are entirely sulfite-free, even those labeled "organic".
