Raisins and Sulfites
Commercially grown dried raisins may be treated with sulfur dioxide gas during processing. They may also be treated with sulfites to extend their shelf life.
Sulfur-containing compounds are often added to dried foods like raisins as preservatives to help prevent oxidation and bleaching of colors. The sulfites used to help preserve dried raisins cause adverse reactions in an estimated one out of every 100 people, who turn out to be sulfite sensitive.
Sulfite reactions can be particularly acute in people who suffer from asthma. The Federal Food and Drug Administration estimates that 5 percent of asthmatics may suffer a reaction when exposed to sulfites.
Foods that are classified as "organic" do not contain sulfites since federal regulations prohibit the use of these preservatives in organically grown or produced foods. Therefore, concern about sulfite exposure is yet another reason to purchase organic foods.