Compendium of the most significant studies with reference to properties, intake, effects.
Brendler T, Williamson EM. Astaxanthin: How much is too much? A safety review. Phytother Res. 2019 Dec;33(12):3090-3111. doi: 10.1002/ptr.6514.
Abstract. Astaxanthin (AX)-containing preparations are increasingly popular as health food supplements. Evaluating the maximum safe daily intake of AX is important when setting dose levels for these products and currently, there are discrepancies in recommendations by different regulatory authorities. We have therefore conducted a review of approved dose levels, clinical trials of natural AX, and toxicological studies with natural and synthetic AX....© 2019 John Wiley & Sons, Ltd.
Stachowiak B, Szulc P. Astaxanthin for the Food Industry. Molecules. 2021 May 2;26(9):2666. doi: 10.3390/molecules26092666.
Abstract. Xanthophyll astaxanthin, which is commonly used in aquaculture, is one of the most expensive and important industrial pigments. It is responsible for the pink and red color of salmonid meat and shrimp. Due to having the strongest anti-oxidative properties among carotenoids and other health benefits, natural astaxanthin is used in nutraceuticals and cosmetics, and in some countries, occasionally, to fortify foods and beverages. Its use in food technology is limited due to the unknown effects of long-term consumption of synthetic astaxanthin on human health as well as few sources and the high cost of natural astaxanthin. The article characterizes the structure, health-promoting properties, commercial sources and industrial use of astaxanthin. It presents the possibilities and limitations of the use of astaxanthin in food technology, considering its costs and food safety. It also presents the possibilities of stabilizing astaxanthin and improving its bioavailability by means of micro- and nanoencapsulation.
Bjerkeng, B., Peisker, M., Von Schwartzenberg, K., Ytrestøyl, T., & Åsgård, T. (2007). Digestibility and muscle retention of astaxanthin in Atlantic salmon, Salmo salar, fed diets with the red yeast Phaffia rhodozyma in comparison with synthetic formulated astaxanthin. Aquaculture, 269(1-4), 476-489.
Abstract. To elucidate whether astaxanthin plasma concentration, deposition and retention in the muscle (% of ingested dose) and apparent digestibility coefficients (ADC) were influenced by astaxanthin source, triplicate groups of size-graded (initial average weight of 0.69 kg) Atlantic salmon (Salmo salar), individually labelled with PIT-tags were fed two different experimental diets (6 tanks, each containing 20 fish) for 86 days...Copyright © 2007 Elsevier B.V.
Chang MX, Xiong F. Astaxanthin and its Effects in Inflammatory Responses and Inflammation-Associated Diseases: Recent Advances and Future Directions. Molecules. 2020 Nov 16;25(22):5342. doi: 10.3390/molecules25225342.
Abstract. Astaxanthin is a natural lipid-soluble and red-orange carotenoid. Due to its strong antioxidant property, anti-inflammatory, anti-apoptotic, and immune modulation, astaxanthin has gained growing interest as a multi-target pharmacological agent against various diseases. In the current review, the anti-inflammation mechanisms of astaxanthin involved in targeting for inflammatory biomarkers and multiple signaling pathways, including PI3K/AKT, Nrf2, NF-κB, ERK1/2, JNK, p38 MAPK, and JAK-2/STAT-3, have been described. Furthermore, the applications of anti-inflammatory effects of astaxanthin in neurological diseases, diabetes, gastrointestinal diseases, hepatic and renal diseases, eye and skin disorders, are highlighted. In addition to the protective effects of astaxanthin in various chronic and acute diseases, we also summarize recent advances for the inconsistent roles of astaxanthin in infectious diseases, and give our view that the exact function of astaxanthin in response to different pathogen infection and the potential protective effects of astaxanthin in viral infectious diseases should be important research directions in the future.
Nishida Y, Nawaz A, Hecht K, Tobe K. Astaxanthin as a Novel Mitochondrial Regulator: A New Aspect of Carotenoids, beyond Antioxidants. Nutrients. 2021 Dec 27;14(1):107. doi: 10.3390/nu14010107.
Abstract. Astaxanthin is a member of the carotenoid family that is found abundantly in marine organisms, and has been gaining attention in recent years due to its varied biological/physiological activities. It has been reported that astaxanthin functions both as a pigment, and as an antioxidant with superior free radical quenching capacity. We recently reported that astaxanthin modulated mitochondrial functions by a novel mechanism independent of its antioxidant function. In this paper, we review astaxanthin's well-known antioxidant activity, and expand on astaxanthin's lesser-known molecular targets, and its role in mitochondrial energy metabolism.
Li J, Guo C, Wu J. Astaxanthin in Liver Health and Disease: A Potential Therapeutic Agent. Drug Des Devel Ther. 2020 Jun 9;14:2275-2285. doi: 10.2147/DDDT.S230749.
Abstract. ...An understanding of the structure, source and mechanism of action of astaxanthin in the body would not only provide a theoretical basis for its clinical application but could also have important significance in screening and improving related compounds for the treatment of liver diseases. © 2020 Li et al.
Kidd P. Astaxanthin, cell membrane nutrient with diverse clinical benefits and anti-aging potential. Altern Med Rev. 2011 Dec;16(4):355-64.
Abstract. Astaxanthin, a xanthophyll carotenoid, is a nutrient with unique cell membrane actions and diverse clinical benefits. This molecule neutralizes free radicals or other oxidants by either accepting or donating electrons, and without being destroyed or becoming a pro-oxidant in the process. Its linear, polar-nonpolar-polar molecular layout equips it to precisely insert into the membrane and span its entire width. In this position, astaxanthin can intercept reactive molecular species within the membrane's hydrophobic interior and along its hydrophilic boundaries. Clinically, astaxanthin has shown diverse benefits, with excellent safety and tolerability. In double-blind, randomized controlled trials (RCTs), astaxanthin lowered oxidative stress in overweight and obese subjects and in smokers. It blocked oxidative DNA damage, lowered C-reactive protein (CRP) and other inflammation biomarkers, and boosted immunity in the tuberculin skin test. Astaxanthin lowered triglycerides and raised HDL-cholesterol in another trial and improved blood flow in an experimental microcirculation model. It improved cognition in a small clinical trial and boosted proliferation and differentiation of cultured nerve stem cells. In several Japanese RCTs, astaxanthin improved visual acuity and eye accommodation. It improved reproductive performance in men and reflux symptoms in H. pylori patients. In preliminary trials it showed promise for sports performance (soccer). In cultured cells, astaxanthin protected the mitochondria against endogenous oxygen radicals, conserved their redox (antioxidant) capacity, and enhanced their energy production efficiency. The concentrations used in these cells would be attainable in humans by modest dietary intakes. Astaxanthin's clinical success extends beyond protection against oxidative stress and inflammation, to demonstrable promise for slowing age-related functional decline.
Singh KN, Patil S, Barkate H. Protective effects of astaxanthin on skin: Recent scientific evidence, possible mechanisms, and potential indications. J Cosmet Dermatol. 2020 Jan;19(1):22-27. doi: 10.1111/jocd.13019.
Abstract...In this review article, we highlight the pharmacokinetic profile of the antioxidant in brief and describe the findings of various recent published research articles which studied the effect of astaxanthin in improvement of skin health. We also mention the possible mechanisms which form the basis of the positive dermatological effects of astaxanthin and the potential indications of the antioxidant molecule in cosmetology and dermatology. © 2019 Wiley Periodicals, Inc.
Martínez-Álvarez Ó, Calvo MM, Gómez-Estaca J. Recent Advances in Astaxanthin Micro/Nanoencapsulation to Improve Its Stability and Functionality as a Food Ingredient. Mar Drugs. 2020 Aug 1;18(8):406. doi: 10.3390/md18080406.
Abstract. Astaxanthin is a carotenoid produced by different organisms and microorganisms such as microalgae, bacteria, yeasts, protists, and plants, and it is also accumulated in aquatic animals such as fish and crustaceans. Astaxanthin and astaxanthin-containing lipid extracts obtained from these sources present an intense red color and a remarkable antioxidant activity, providing great potential to be employed as food ingredients with both technological and bioactive functions. However, their use is hindered by: their instability in the presence of high temperatures, acidic pH, oxygen or light; their low water solubility, bioaccessibility and bioavailability; their intense odor/flavor. The present paper reviews recent advances in the micro/nanoencapsulation of astaxanthin and astaxanthin-containing lipid extracts, developed to improve their stability, bioactivity and technological functionality for use as food ingredients. The use of diverse micro/nanoencapsulation techniques using wall materials of a different nature to improve water solubility and dispersibility in foods, masking undesirable odor and flavor, is firstly discussed, followed by a discussion of the importance of the encapsulation to retard astaxanthin release, protecting it from degradation in the gastrointestinal tract. The nanoencapsulation of astaxanthin to improve its bioaccessibility, bioavailability and bioactivity is further reviewed. Finally, the main limitations and future trends on the topic are discussed.
Astaxanthin 
beta,beta-carotene-4,4'-dione 
