Trends in Biotechnology
Haematococcus astaxanthin: applications for human health and nutrition
Section snippets
Bioavailability and pharmacokinetics
The various steps of digestion, absorption and plasma transport of dietary carotenoids in mammals have been reviewed [5]. In the plasma, non-polar carotenoids such as β-carotene, α-carotene or lycopene, are mostly transported by very low density lipoproteins (VLDLs) and low density lipoproteins (LDLs) and polar carotenoids, such as zeaxanthin or lutein, are more likely to be transported by LDLs and high density lipoproteins (HDLs). The only study on humans to date confirmed the bioavailability
Astaxanthin as an antioxidant
Free radicals (e.g. hydroxyl and peroxyl radicals) and highly reactive forms of oxygen (e.g. singlet oxygen) are produced in the body during normal metabolic reactions and processes. Physiological stress, air pollution, tobacco smoke, exposure to chemicals or exposure to ultraviolet (UV) light, can enhance the production of such agents. Phagocytes can also generate an excess of free radicals to aid in their defensive degradation of the invader. Free radicals can damage DNA, proteins and lipid
Astaxanthin as a photoprotectant
Exposure of lipids and tissues to light, especially UV-light, can lead to production of singlet oxygen and free radicals and photo-oxidative damage of these lipids and tissues [7]. Carotenoids have an important role in nature in protecting tissues against UV-light mediated photo-oxidation and are often found in tissues directly exposed to sunlight. Astaxanthin can be significantly more effective than β-carotene and lutein at preventing UV-light photooxidation of lipids [14]. Oxidative damage to
Astaxanthin and eye health
Two of the leading causes of visual impairment and blindness are age-related macular degeneration (AMD) and age-related cataracts. Both diseases appear to be related to light-induced oxidative processes within the eye 7, 15. It is therefore not surprising that factors related to oxidation have been shown in epidemiological studies to be related to an elevated risk for AMD. A high dietary intake of carotenoids, specifically lutein and zeaxanthin (from spinach, kale, and other leafy green
Astaxanthin and skin health
Excessive exposure of unprotected skin to sunlight results in sunburn and can also lead to photo-induced oxidation, inflammation, immunosuppression, aging and even carcinogenesis of skin cells. Pre-clinical studies show that typical dietary antioxidants, such as α-tocopherol, ascorbic acid or β-carotene, could reduce such damage 20, 21, 22.
Astaxanthin is believed to protect the skin and eggs of salmon against UV-light photo-oxidation 23, 24. Astaxanthin supplementation helped protect the
Astaxanthin and inflammation
In inflammation-related clinical conditions such as Crohn's disease, toxic reactive oxygen species (ROS) are released by phagocytic leucocytes at the site of inflammation (intestinal mucosa and lumen). These, plus increased concentrations of neutrophiles at the site of inflammation, create a pro-oxidative balance that leads to lower levels of antioxidant vitamins and increased levels of markers of oxidative stress and lipid peroxidation [27]. Furthermore, oxidants have been directly linked to
Astaxanthin and heart health
High blood levels of LDL-cholesterol (the ‘bad’ cholesterol) are associated with an increased risk of atherosclerosis. However, HDL blood levels are inversely correlated with coronary heart disease and are indicative of protection against atherosclerosis. Usually LDL in plasma is not oxidized and oxidation of LDL is believed to contribute to the development of atherosclerosis [32] thus it might be possible to reduce the risk of atherosclerosis by antioxidant supplementation. Epidemiological and
Astaxanthin and cellular health
In the mitochondria, multiple oxidative chain reactions generate the energy needed by the cell but produce large amounts of free radicals that need to be neutralized to maintain proper mitocondrial function. It is hypothesized that the cumulative oxidative damage to mitochondria is the main culprit for the senescence of cells, which in turn is responsible for aging [37]. The efficacy of astaxanthin in preventing in vitro peroxidation of mitochondria of rat liver cells can be as high as 100
Anti-cancer properties of astaxanthin
Several studies have demonstrated the anti-cancer activity of astaxanthin in mammals. Astaxanthin protected mice from carcinogenesis of the urinary bladder by reducing the incidence of chemically induced bladder carcinoma [44]. Rats fed a carcinogen but supplemented with astaxanthin had a significantly lower incidence of different types of cancerous growths in their mouths than rats fed only the carcinogen. The protective effect of astaxanthin was even more pronounced than that of β-carotene
Astaxanthin in detoxification and liver function
The liver is a complex organ in which intense catabolism and anabolism take place. Liver functions include active oxidation of lipids to produce energy, detoxification of contaminants, and destruction of pathogenic bacteria, viruses and of dead red blood cells. These functions can lead to significant release of free radicals and oxidation byproducts and therefore it is important to have mechanisms that protect liver cells against oxidative damage. Astaxanthin is much more effective than vitamin
Astaxanthin and the immune response
Immune response cells are particularly sensitive to oxidative stress and membrane damage by free radicals because they rely heavily on cell-to-cell communications via cell membrane receptors. Furthermore, the phagocytic action of some of these cells releases free radicals that can rapidly damage these cells if they are not neutralized by antioxidants [53]. Astaxanthin significantly influences immune function in several in vitro and in vivo assays using animal models. Astaxanthin enhances in
Astaxanthin and neurodegenerative diseases
The nervous system is rich in both unsaturated fats (which are prone to oxidation) and iron (which has strong prooxidative properties). These, together with the intense metabolic aerobic activity and rich irrigation with blood vessels found in tissues of the nervous system, make tissues particularly susceptible to oxidative damage [58]. There is substantial evidence that oxidative stress is a causative or at least ancillary factor in the pathogenesis of major neurodegenerative diseases
Safety of Haematococcus astaxanthin
A recent study was designed specifically to examine the effects by dietary astaxanthin on the health of humans [63]. In this study, 33 healthy adult volunteers were given natural astaxanthin supplementation over a period of 29 days. Each subject consumed daily either 3.85 mg astaxanthin (low dose) or 19.25 mg astaxanthin (high dose). Volunteers underwent a complete medical examination before, during, and at the end of the study and no ill effects or toxicity from ingestion of the astaxanthin
Production and future of Haematococcus astaxanthin
Commercial production of Haematococcus astaxanthin is very recent. Astaxanthin accumulation in Haematococcus is induced under stressful growth conditions. Thus, producers that use large-scale, outdoor, systems have adopted a two stage strategy whereby the first stage consists in growing Haematococcus biomass under conditions conducive to fast growth in enclosed photobioreactors followed by a second stage in which carotenogenesis is induced by changing the cells' environment to stress promoting
Conclusion
Based on recently published literature we conclude that Haematococcus astaxanthin supplementation might be a practical and beneficial strategy in health management. This conclusion is supported by astaxanthin's strong antioxidant activity and its possible role in health conditions in several tissues in the human body and by the results of a user survey. As consumers become aware of the putative benefits of Haematococcus astaxanthin supplementation, and as commercial production is optimized and
Acknowledgments
The authors thank J. Dore, M. Lopez and M. Unson for assistance gathering and reviewing the published literature.
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