Astaxanthin (AX) has become a rock star carotenoid with its incredible antioxidant power and intriguing marine origin. AX and its chemical cousin canthaxanthin are found in salmon, Arctic char, trout, shrimp, lobster, crab and crayfish, coloring the flesh a characteristic pink. These fish and crustaceans ingest algae that actually synthesize the carotenoids. Most supplemental AX comes from the marine green algae Haematococcus pluvialis or krill oil. Antarctic krill (Euphausia superba) live mainly in the dark and are colorless, but during the brief summer they sometimes get caught on the sea surface in the glaring endless sunshine. In minutes they release stored AX and turn red—a super sunblock!
There are over 600 carotenoids found in nature. Plants, algae, and microorganisms are all exposed to sunlight and various environmental toxins, and carotenoids provide antioxidant protection by capturing and quenching free radicals. Luckily we can ingest carotenoids and they also protect us. However antioxidant compounds are chemical “sacrificial lambs”, meaning they preferentially react with free radicals and spare plant/animal tissues. So, by nature, they’re unstable and degrade quickly. Plants, algae, and microorganisms continually synthesize fresh carotenoids to replace those degraded. Similarly, humans must continually ingest fresh carotenoids to remain protected.
Let’s take a look at various AX sources to determine how effective they are in terms of cost and nutraceutical properties.
Shrimp waste is an inexpensive source of AX, however the compound fully degraded in 17 days, even when the shrimp extract was stored airtight in a dark refrigerator. Acidified fermented shrimp/lobster waste was more stable under the same conditions, but in order to ferment properly air, light, and heat are needed, which degraded 97 percent of AX. Dried salted shrimps, popular in Asia and Latin America, lost 83 percent of AX during the sun drying and cooking process, and virtually all was gone by the time the product was sold.
AX, canthaxanthin and other carotenoids had little degradation in salmon that was frozen six months whole, with skin, head and organs intact. However, portioned fillets of salmon or rainbow trout lost carotenoids slightly to drastically depending on the study. As expected, smaller portions and longer storage increased AX degradation. AX stored within fish, krill, or vegetable oil is quite stable frozen, refrigerated or at room temperature in the dark.
Wild salmon have about 10 times the AX that farmed do. Farmed fish have little access to algae or krill, therefore synthetic AX is added to fish feed to provide color and good health. Krill is too expensive; algae extracts are cheaper, but not much. Mainstream medical research now utilizes primarily synthetic AX or derivatives being developed into drugs. Natural but not synthetic AX is typically linked to one or two fatty acids which may increase bioavailability in some fish and mammals, and in all cases AX is better absorbed if eaten with fats. However there’s no evidence that synthetic AX is inferior with respect to human health benefits.
Effective truly natural sources of AX are fresh wild-caught seafood or high quality krill oil, both expensive and subject to market fluctuations. The surprising alternative is that tomatoes, carrots, lettuce, tobacco and brewer’s yeast have all been genetically engineered to produce AX. These are inexpensive, plentiful crops which can be eaten directly or extracted for supplements. We need to ask ourselves whether billions of people on the planet who cannot afford fresh wild caught seafood or any sort of nutritional supplement should be denied AX-containing vegetables.