Food manufacturers (Foodchem) mostly use some ingredients to prolong the shelf life of food or to enhance its color, texture or flavor. According to the Asthma and Allergy Foundation of America, natural foods cause most allergic reactions; however, a few food additives can cause problems. These include nitrates, nitrites, sulfates, sulfites, MSG (mono sodium glutamate) and benzoates.

Preservatives keep food from spoiling and maintain freshness and color or flavor foods. They are often added to baked goods, meats, jellies and beverages. Preservatives include ascorbic acid, citric acid, sodium benzoate, calcium propionate, vitamin E, BHA and BHT. Calcium propionate is a chemical preservative used in cheeses, and citric acid is used as a buffer and neutrilizer in dressings, cheeses and canned fruit juices. BHA (butylated hydroxytoluene) and BHA (butylated hydroxyanisole) are antioxidants commonly used in breakfast cereals to help prevent change in color, odor or flavor.

According to the Food and Drug Administration, a food additive is any substance added to food, including preservatives, food coloring, flavor enhancers, thickeners, stabilizers, nutrients and sweeteners. Examples of food additives are sucrose (sugar), glucose, fructose, sorbitol, mannitol, corn syrup, high fructose corn syrup, saccharin and aspartame, used for sweetening; or FD&C Yellow Nos. 5 and 6, annato or beta carotene, used for food coloring. Thickeners and stablizers include pectin, guar gum, carrageenan, xanthan gum, whey and gelatin. Breads and baked goods often contain leavening agents such as baking soda, monocalcium phosphate and calcium carbonate.

The FDA regulates the use of preservatives and additives, approving them based on the best science available for "reasonable certainty of no harm to consumers." Additives are subject to ongoing safety reviews, with the intent that consumers should feel safe with the foods they eat.

The FDA has an "Everything Added to Food in the United States" database, which contains toxicological, chemical and administrative information on 3,000 substances, including food additives. Companies that want to use food additives have to go through an extensive petition process that involves testing the toxicology, chemistry, antimicrobial and environmental aspects of food additives.