Thank carotenoids, the same pigments that make carrots orange. Those magical antioxidants combat the damaging effects of free radicals. The carotenoid in salmon is a particularly potent antioxidant known as astaxanthin, which has been shown to protect against heart disease, cancer, inflammation, eye diseases, general aging and many other conditions. Astaxanthin is produced by phytoplankton, tiny plants that use it to shield themselves from ultraviolet radiation. Shrimp, krill and other tiny crustaceans eat the phytoplankton and accumulate astaxanthin in their bodies (which is what makes them pink), then salmon eat them and store the astaxanthin in their skin and muscles. Sockeye, which feed mainly on plankton, have the deepest orange color, whereas pink and chum salmon (most often canned) are the lightest. Many farmed Atlantic salmon are given feed with added synthetic astaxanthin (and sometimes another manufactured pigment, canthaxanthin) to turn their flesh orange.