Manufacturers use food additives for many reasons, including enhancing the color or flavor of foods, increasing nutrients, or decreasing microbial effects. The Food and Drug Administration database called EAFUS (Everything Added to Food in the United States) lists nearly 3,000 substances allowed for addition to foods in the U.S. Of those, about 35 are food dyes approved for use by the FDA.
Many parents report a possible connection between their child ingesting food coloring and flares of eczema, hives, or even asthma. Two artificial dyes often reported as culprits are Yellow # 5 (tartrazine) and Red #40. However, most reports of allergic reactions to synthetic food dyes are anecdotal.
The body's immune system responds to proteins. Artificial additives including Yellow #5 and Red #40 do not contain protein, so true allergies to synthetic food colorings are fortunately very rare. There are no specific allergy tests for artificial food dyes, and adverse reactions may be described as food intolerances or sensitivities rather than allergies.
On the other hand, natural food dyes are derived from insects, plants, or animals. Since these additives contain protein, they could in theory cause a true allergic reaction. One example is carmine (E120), also called cochineal extract. This natural food coloring is made from beetles and has been used as a red dye for centuries. Cochineal extract is currently used to color various types of fruit juice, candy, ice cream, yogurt, and several other types of foods. In fact, it was formerly used by Starbucks to color some of its beverages.
While cochineal dye is not harmful to most people, there have been reports of patients having allergic reactions to carmine, ranging from hives to anaphylaxis. People who develop hives or more serious symptoms after ingesting carmine should avoid it, and they should be seen by an allergist for evaluation and management.
Annatto (E160b) is a second natural food dye that has been reported to cause allergic reactions. Annatto is derived from a tree and is used to give foods a yellow color. It can be found as an additive in cheese, cereal, and certain beverages.
Although allergic reactions to food dyes are rare, if you suspect your child has had an allergic reaction or sensitivity to food coloring, it is important to discuss this with your child's physician. He or she can help you decide if referral to an allergy specialist would be beneficial. Keeping a record of food additives that were ingested by your child, as well as the timing and type of reaction, will greatly assist in the diagnosis.