Astaxanthin is a carotenoid pigment found in nature. It gives the pink colour to salmon and shrimp, and it's what turns flamingo feathers pink when they eat algae and shrimp. It is known to be one of the most powerful antioxidants, and because it does not have the capacity to turn into a pro-oxidant in the body, it has numerous health benefits.
In the body, astaxanthin can locate and neutralise the free radicals which can cause cell damage. It is thought that it may also help to lessen the build up of plaque in arteries, and it may have neuro-protective properties too. Antioxidants in general tend to support the immune system, so it's reasonable to assume that astaxanthin also does.
One of the most important potential applications of astaxanthin is in eye health. The pigment has a similar chemical make up to lutein and zeaxanthin, which are known to help prevent cataracts and to reduce the risk of macular degeneration.
Astaxanthin has also been shown to help improve skin elasticity, so it is sometimes used in beauty products.
The best dietary sources of astaxanthin are wild salmon, krill, shrimp and lobster. It can also be taken as a supplement, typically in capsule form.