Sulfites are preservatives that are added to many different foods, condiments, teas and herbs. They act as antimicrobial agents inhibiting growth of mold and bacteria, as antioxidants slowing the rate of oxidation of fats and lipids in foods and keep foods fresh by slowing ripening and enzymatic activity. Although sulfites do not usually harm humans, people that are sensitive to them can have adverse reactions, such as breathing problems, headaches, flushed face or accelerated heartbeat. The FDA has required food manufacturers to list sulfites on their product labels if they contain them.
Sulfites are used in Chinese medicine to keep mold from spoiling the plants and to keep bugs away. The method used to preserve Chinese herbs is to lay the harvested plants on a screen and heat or burn sulfite below it. The smoke slowly rises to the herbs to preserve them. The traces of sulfites on most Chinese herbs can be small. Andrew Ellis of Spring Wind Herbs searched FDA and California Department of Health Services records for sulfite-sensitivity complaints from Chinese herb use and found none.
The Food and Drug Administration states that you might find sulfites in instant tea and liquid tea concentrates. It is recommended to look at the product label to check.
Dried herbs and spices that are used to season foods often contain sulfites as preservatives. This extends shelf life and preserves color and flavor of the herbs.
You will hear sulfites called by different names. Sulfur dioxide, sulphurous acid, sodium bisulphate, sodium sulphite, potassium bisulphite and potassium metabisulphite all refer to this type of preservative. Check product labels when you are buying food items to see if they contain any of these. This is especially important if you are sensitive to sulfites.