Why skin doesn't always react the same to the sun
With the first warm weeks of the year, not only does the light change, but also the stress our skin is exposed to daily.
UV radiation is one of the strongest triggers of oxidative processes in human tissue. Cell membranes, collagen structures, and mitochondrial processes within skin cells are particularly affected. It is precisely in these areas that free radicals are generated, which in the long term are associated with moisture loss, loss of elasticity, and photoaging of the skin.[1]
Interestingly, the skin has its own protective mechanisms. Melanin is not produced randomly. It is a direct reaction of the body to UV exposure. From a biological perspective, a tan is therefore not purely a cosmetic effect, but part of a complex protective system.
In this context, particular attention receives special attention. Astaxanthin.
What exactly is astaxanthin?
Astaxanthin is a deep red carotenoid from microalgae. Haematococcus pluvialis. The algae produce this substance under intense sunlight as a natural protection mechanism against oxidative stress.[2]
The crucial factor here is the special molecular structure of astaxanthin.
Unlike many other antioxidant substances, astaxanthin can be directly incorporated into cell membranes and stabilize different areas of the membrane structure there.[3]
This allows astaxanthin to be scientifically investigated particularly in areas where free radicals and oxidative processes play a special role – such as in skin, retina and other metabolically active tissues.
Skin, UV radiation and light-induced cell stress
The role of astaxanthin in light-induced skin aging and UV-induced cell stress is currently being researched particularly intensively.
In a study with healthy volunteers, various skin parameters were examined after several weeks of astaxanthin intake, including skin hydration and elasticity.[4]
Also of interest is the so-called minimal erythema dose. This refers to the amount of UV radiation needed to cause visible skin reddening.
A randomized, double-blind, placebo-controlled human study investigated the effects of astaxanthin supplementation over several weeks on the skin's response to UV radiation. Changes in the minimal erythema dose and skin hydration were among the parameters measured.[5]
Astaxanthin interacts with the lipid layers of biological membranes due to its fat-soluble structure. This property is one reason why the carotenoid is of scientific interest in the context of oxidative stress on the skin.[2,3]
Retina, light and visual strain
Besides the skin, the retina is increasingly coming into focus.
The retina is one of the most metabolically active tissues in the body and is sensitive to light-induced oxidative stress.
Experimental studies therefore investigate the question of what influence astaxanthin might have on oxidative processes in retinal cells.[7]
Astaxanthin has also been studied in humans in connection with visual strain. The focus has been on visual fatigue and accommodation – the eye's ability to switch between different focal distances.[8]
This area of research is particularly interesting because our eyes are often subjected to long periods of visual strain in everyday life, for example through screen work and continuous close-up focusing.
Stress, regeneration and physical performance
The formation of reactive oxygen species also increases significantly during intense physical activity.
Muscles and mitochondria are particularly sensitive to persistent oxidative stress, as they constantly process high amounts of energy.
Astaxanthin is coming into focus because oxidative stress in muscle cells is closely linked to the membranes of the mitochondria and thus to processes of cellular energy production.
Therefore, a study with young football players analyzed how astaxanthin supplementation affects various markers of muscle damage and oxidative stress.[9]
This expands astaxanthin research beyond the skin to other areas where high metabolic activity and oxidative processes coincide.
Why astaxanthin intake plays a role
Astaxanthin is a fat-soluble carotenoid.
Therefore, what is crucial is not only the amount of astaxanthin ingested, but also the form in which it is made available to the body.
Human studies on the uptake of astaxanthin show that the carotenoid is detectable in the blood after oral administration and is transported via lipoproteins.[11]
As with other fat-soluble carotenoids, bioavailability therefore plays an important role in the scientific evaluation of astaxanthin.
Astaxanthin in the context of oxidative stress
The different research areas appear very different at first glance: skin and UV radiation, retina and visual strain, and muscles and physical activity.
However, the common denominator lies in the underlying biological processes.
In all three areas, tissues that are particularly metabolically active or exposed to external stresses experience an increased formation of reactive oxygen species.
That is precisely why astaxanthin appears in such diverse fields of research.
Its unique molecular structure and ability to interact with lipid-rich cell membranes make the carotenoid an interesting subject of research in connection with oxidative stress.
Assessment of the current state of research
Current research is primarily investigating astaxanthin in connection with:
- UV-induced processes and skin parameters
- oxidative stress in cell membranes
- retinal and visual strain processes
- physical stress and regeneration
- Bioavailability and absorption of fat-soluble carotenoids
In addition to experimental studies, initial human studies are also available.
At the same time, study designs, dosages, study periods, and parameters considered differ, sometimes significantly. The clinical significance of individual results and potential long-term effects therefore remain the subject of further research.
Conclusion
Astaxanthin is of particular scientific interest because its special molecular structure is closely associated with lipid-rich cell membranes.
From the skin to the retina and the muscles, research focuses on tissues in which oxidative processes play a special role.
UV radiation, in particular, makes visible how closely environmental pollution, cell membranes, and the body's own protective mechanisms are interconnected.
Current research on astaxanthin is therefore increasingly trying to understand what role the carotenoid can play within these complex processes.
Sources
[1] Pillai S. et al. (2005). Ultraviolet radiation and skin aging: roles of reactive oxygen species, inflammation and protease activation. Free Radical Biology and Medicine, 40(9), 1603–1616.
[2] Ambati R.R. et al. (2014). Astaxanthin: sources, extraction, stability, biological activities and its commercial applications. Marine Drugs, 12(1), 128-152.
[3] Guerin M. et al. (2003). Haematococcus astaxanthin: applications for human health and nutrition. Trends in Biotechnology, 21(5), 210-216.
[4] Tominaga K. et al. (2012). Cosmetic benefits of astaxanthin on human subjects. Acta Biochimica Polonica, 59(1), 43–47.
[5] Ito N. et al. (2018). The protective role of astaxanthin for UV-induced skin deterioration in healthy people – a randomized, double-blind, placebo-controlled trial. Nutrients, 10(7), 817.
[7] Nakajima Y. et al. (2008). Astaxanthin, a dietary carotenoid, protects retinal cells against oxidative stress. British Journal of Nutrition, 100(2), 389-395.
[8] Nagaki Y. et al. (2002). Suppression of human accommodation fatigue by astaxanthin. Journal of Clinical Therapeutics and Medicines, 18(1), 73-79.
[9] Djordjevic B. et al. (2012). Effect of astaxanthin supplementation on muscle damage and oxidative stress markers in elite young soccer players. Journal of Sports Medicine and Physical Fitness, 52(4), 382-392.
[11] Østerlie M. et al. (2000). Plasma appearance and distribution of astaxanthin E/Z and R/S isomers in plasma lipoproteins of men after single dose administration. Journal of Nutritional Biochemistry, 11(10), 482-490.