Blue 2 is a synthetic chemical produced by the fusion of sodium phenylgycinate and indoxyl in a mixture of sodamide and caustic soda. Indigo is the blue dye naturally derived from plants while indigotine is a petroleum product. Blue 2 is used as artificial coloring, mainly to make the products visually appealing and for marketing purposes.
Artificial coloring like blue 2 are usually used as an ingredient in low nutritional value foods like gelatine desserts, ice cream, biscuits, soda pop, candies, cereals, sports drinks, soft drinks and pet foods. They are also added to tablets and capsules. Blue 2 is also used as a biological stain, photometric detector and diagnostic aid like kidney function tests.
The Food and Drug Administration declared Blue 2 as a safe ingredient for food and food supplements. However, blue 2 does not add any nutritive value to food and because there are no reports of human studies about the product, its safety is still questionable.
Blue 2 has been known to cause hyperactivity, chromosomal damage, nausea, high blood pressure, vomiting, breathing problems, allergic reactions and skin rashes. This chemical has been found to cause brain cancer in rats. Blue 2 has been banned in Sweden, Switzerland, Norway, Germany, France, Belgium, Australia and the British Commonwealth.
Indigo carmine, 5,5'-indigodisulfonic acid sodium salt, indigotine, FD&C Blue #2, Indigo Blue