Astaxanthin: synthetic or natural?

There is also synthetic astaxanthin. This is artificially produced in the laboratory from petrochemicals. This form of astaxanthin is less bioavailable than the natural form and is not approved for human consumption, but as an additive for animal feed. Synthetic astaxanthin is often used in aquaculture, for example to give it a color typical of salmon. Rainbow trout, which have a rather white flesh, get a corresponding color in this way and are sold as salmon trout.
Natural astaxanthin is produced using the microalgae Haematococcus pluvialis, a freshwater algae with a very specific growth cycle. The alga begins to grow as a moving, green flagella (A). If the growth conditions deteriorate, the alga changes its morphology and it strengthens its cell wall (B). In this state, the cell loses its flagellation and is no longer free to move. If the stressors continue to increase, the alga begins to accumulate reddish astaxanthin to protect itself (C). Depending on the intensity of the stress factors, the astaxanthin content in the cell continues to increase (D). This state is reversible as soon as favorable conditions arise.
Despite the differences mentioned, the share of natural astaxanthin from microalgae is less than 1% of the world market compared to the synthetic product. This is mainly due to the price difference, since the production effort for natural astaxanthin from microalgae is much higher. Nevertheless, global demand for natural astaxanthin has grown rapidly in recent years.