Exploring Astaxanthin in Nature
Astaxanthin, a member of the extensive carotenoid family, represents a group of naturally occurring organic fat-soluble compounds found in various natural sources. Carotenoids, broadly categorised into carotenes and xanthophylls, encompass astaxanthin, which belongs to the latter subgroup. This naturally potent plant pigment is present in a diverse range of foods, with notable concentrations found in specific micro-algae.
Survival Strategies: Micro-Algae and Astaxanthin
Given the dietary habits of numerous aquatic species that include algae in their nutrition, astaxanthin can also be traced in certain aquatic creatures, notably in fish and shellfish. Varieties such as trout, salmon, krill, shrimps, crayfish, lobsters, and crabs feature astaxanthin as part of their nutritional composition. Notably, astaxanthin finds its primary sources in micro-algae like Haematococcus pluvialis and Chlorella zofingiensis. In these microorganisms, astaxanthin serves as a protective substance in response to stressors such as temperature fluctuations, nitrogen scarcity, intense light exposure, among others. It emerges as a pivotal component for the survival of these aquatic plants.
Astaxanthin Absorption: A Fat-Soluble Journey
Astaxanthin, characterised as a fat-soluble compound that structurally resembles a fatty acid, is absorbed in a manner akin to fatty acids within the body. This mechanism requires the presence of dietary fat for absorption in the intestine. Therefore, the optimal approach involves the consumption of astaxanthin alongside a meal rich in dietary fat, as inadequate fat intake significantly impedes its absorption.
In the intestinal environment, astaxanthin combines with bile, forming minute fat droplets referred to as micelles. These micelles can be substantially absorbed by the cells within the intestinal mucosa. Subsequently, astaxanthin is assimilated into chylomicrons and transported into the lymphatic system. Within the systemic circulation, these chylomicrons undergo degradation by the enzyme lipoprotein lipase. Consequently, they connect to lipoproteins responsible for conveying astaxanthin to various tissues throughout the body.
In contrast to several other carotenoids, such as beta-carotene, astaxanthin lacks pro-vitamin A activity within the body, implying it cannot convert into active vitamin A when required. Nonetheless, astaxanthin stands as an exceptional antioxidant.
Astaxanthin's Unique Antioxidant Power
Astaxanthin is a formidable antioxidant, earning its epithet as the "king of carotenoids." Extensive research underscores its distinction as one of the most potent naturally occurring antioxidants. Astaxanthin's efficacy in combating free radicals surpasses that of fellow antioxidants, including carotenoids like canthaxanthin, lutein, zeaxanthin, as well as vitamins E and C.
Antioxidants, collectively, serve to avert the formation and detrimental impact of reactive entities, commonly known as free radicals. A surplus of free radicals in the body can incite harmful chain reactions leading to oxidative stress, with potential damage to cellular structures, including genetic material such as DNA.
Astaxanthin's Shield: Antioxidant Mechanisms
Astaxanthin's unique mode of action involves electron donation to free radicals, thereby stabilising these otherwise unstable reactive entities. Furthermore, the compound's distinctive structure enables it to adhere to both the external and internal aspects of cell membranes. This comprehensive protection effectively shields cell membranes against free radicals and oxidative stress.