Astaxanthin (ATX), a red amphiphilic keto-carotenoid, has attracted significant attention in the food and cosmetic industries due to its potent antioxidant properties, being 10 to 1000 times more effective than other natural antioxidants, and offering a wide range of health benefits, including cardioprotective, hepatoprotective, neuroprotective, anti-inflammatory, anticancer and skin-rejuvenating effects. Natural ATX is produced by the microalga Haematococcus pluvialis and accumulates in organisms such as shrimp and salmon that feed on it. At the industrial scale ATX can also be derived from the yeast Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma). The European Union (EU) approved ATX-rich oleoresin from H. pluvialis as novel food. Other novel dietary sources of ATX include oils from crustacean Calanus finmarchicus and Antarctic krill. Although natural ATX offers various benefits, it faces challenges such as low stability, variability in pigment composition, and, most importantly, a high price. Consequently, a significant portion, about 40%, of the ATX available on the market is synthetic. However, synthetic ATX exhibits weaker antioxidant activity compared to its natural counterpart due to the absence of accompanying bioactive compounds and its differing isomer composition. According to EU regulation 2020/998, synthetically obtained astaxanthin-dimethyldisuccinate is approved as a feed additive for fish and crustaceans. The European Food Safety Authority has set the acceptable daily intake for both natural and synthetic ATX at 0.2 mg/kg body weight. ATX is gaining broader application as new biological properties are discovered, driving market growth.