Canthaxanthin is a carotenoid and a xanthophyll; a red pigment that is produced by some flowers and crustaceans. This chemical is responsible for the pink color of the plumage of flamingoes and the flesh of salmon, which build up the pigment from their diet of krill.

Canthaxanthin has come to media attention for its use in aquaculture, particularly salmon farming, in which it is used to give the salmon a more appealing color than the otherwise grey or pale yellow hue. It is also used in poultry farming to enhance the color of the skin of chickens and give egg yolks a richer color. In both cases, the pigment have would come from a source in the diet of the animal in the wild, however, in industrial farming, synthesized canthaxanthin is supplied in the feed.

In the United States, canthaxanthin is an FDA-approved food additive color. Its inclusion in chicken feed is regulated at a maximum of 4.41mg/kg of feed and need not be declared on labels of the end product. Its inclusion in fish feed is regulated at a maximum of 80mg/kg and must be declared on labels of the end product. The European Union regulates the maximum amount of canthaxanthin in fish feed at 25mg/kg. Canada regulates it in fish feed at 30mg/kg.

Canthaxanthin is a primary component in tanning pills. However, the FDA has not approved the use of canthaxanthin as a cosmetic, and in 1988 deployed Federal Marshals to seize the stocks of a distributor in Brooklyn who was marketing canthaxanthin supplements under the name "French Bronze". This seizure and the FDA's stated position on canthaxanthin has resulted in the marketing of such supplements as "an ultra-violet photon absorber, a single and triplet oxygen quencher, and a free radical deactivator". High concentrations of canthaxanthin in the human body can lead to crystalline deposits on the retina. This condition, called canthaxanthin retinopathy, is a subject of ongoing study, but seems to be reversible by the body once high levels of canthaxanthin intake are ceased.

My interest in this chemical was precipitated by an article in the New York Times (online), "Farmed Salmon Looking Less Rosy" by Marian Burros in the May 28, 2003 Dining & Wine section, <>. Supporting information was found in the article "Salmon with a Tan" by Lauren Lapointe-Shaw in Everyday Science, a publication of the Office for Chemistry and Society, McGill University, <> and from the UK Food Standards Agency, an independent food safety watchgroup, <>. The article "Tanning Pills", October 18, 2000 from the Office of Cosmetics and Colors Fact Sheet, Center for Food Safety and Applied Nutrition, USFDA, <> provided information on the regulatory enforcement of the pigment as a dietary supplement, as did a website that promotes supplements for healthy living, <>. The Code of Federal Regulation - Title 21 - Food and Drugs section 73.75 (revision April 1, 2002) was consulted for information on the regulation of canthaxanthin as a food additive in the United States. This narrative bibliography is intended as an experiment.