Canthaxanthin

Canthaxanthin is a ketocarotenoid with the molecular formula C40H52O2, featuring conjugated double bonds that give it a deep red-orange color. It is synthesized by certain microalgae, bacteria, and fungi, and accumulates in the tissues of animals that consume these organisms. For example, the pink plumage of flamingos and the red flesh of salmon and trout are partly due to canthaxanthin, either directly or as a metabolite of other carotenoids.¹

In nature, canthaxanthin serves as a photoprotective pigment and antioxidant, shielding cells from oxidative damage. It is also a precursor to vitamin A in some animals, though its provitamin A activity is lower than that of beta-carotene.²

Canthaxanthin is approved as a food additive in the European Union (E161g) and in many other countries, where it is used to color foods such as cheeses, sauces, and beverages. In aquaculture, it is added to feed for farmed salmon and trout to impart the characteristic pink flesh color that consumers expect.

The use of canthaxanthin in animal feed is regulated to ensure safety, with acceptable daily intakes established by food safety authorities. In the EU, the additive is permitted only in certain feed for fish and poultry, and maximum residue levels are set to protect consumers.³

Canthaxanthin is the active ingredient in some over-the-counter tanning pills, which claim to produce a natural-looking tan by depositing the pigment in the skin. However, the use of such pills is not approved by regulatory agencies like the U.S. Food and Drug Administration, which has linked them to serious side effects.

Adverse effects include retinopathy, a condition in which canthaxanthin crystals accumulate in the retina, potentially causing visual disturbances. Other reported effects include liver damage and skin discoloration. Because of these risks, tanning pills containing canthaxanthin are banned in several countries, and health authorities advise against their use.⁴

Beyond its commercial uses, canthaxanthin has been studied for its potential health benefits, including antioxidant and anti-inflammatory properties. Some research suggests it may help protect against UV-induced skin damage and certain cancers, though evidence is preliminary.⁵

In the natural world, canthaxanthin is responsible for the red coloration of the brine shrimp Artemia salina, which in turn colors the flamingos that feed on them. It also occurs in the fungus Cantharellus cinnabarinus, from which it was first isolated in the 1950s. Interestingly, canthaxanthin is used in some countries as a pigment for egg yolks, giving them a deeper yellow-orange hue.⁶

Carotenoid

A class of natural pigments responsible for red, orange, and yellow colors in plants and animals.

Xanthophyll

A type of carotenoid that contains oxygen atoms, often yellow or orange.

Retinopathy

Damage to the retina of the eye, which can be caused by canthaxanthin accumulation.

Provitamin A

A substance that the body can convert into vitamin A.