Astaxanthin: what should we know about this pigment?

Due to its unique molecular structure, astaxanthin possesses chemical properties that provide benefits for skin care.

• Astaxanthin to combat oxidative stress.

  Oxidative stress is a phenomenon directly linked to the overproduction of free radicals by the body. These compounds are highly unstable due to their unpaired electron. They degrade various components essential for maintaining firm and elastic skin, such as collagen and elastin, thereby accelerating skin sagging and the appearance of wrinkles. It's worth noting that the production of free radicals is significantly amplified by certain external factors, such as the sun's UV rays (this is referred to as photoaging), pollution, smoking, stress, and so on.

  Thanks to its 13 conjugated polyunsaturated double bonds, astaxanthin is capable of neutralising free radicals. Moreover, its amphiphilic structure allows it to insert itself into the bilayers of cell membranes and limit the damage caused by lipid peroxidation. This phenomenon, triggered by oxidative stress, is responsible for tissue damage and affects not only the membranes of cells, but also the overall barrier function of the skin. By capturing and neutralising free radicals, astaxanthin therefore has a significant protective effect on the skin.

• Astaxanthin safeguards collagen from degradation.

  A study also revealed that astaxanthine is capable of protecting the collagen from degradation. Indeed, astaxanthine works by increasing the release of TIMP-1, a matrix metalloproteinase inhibitor. These are enzymes that degrade collagen and thus disrupt the extracellular matrix. Astaxanthine therefore has a dual protective effect on collagen, by eliminating free radicals and inhibiting matrix metalloproteinases.

• Astaxanthin to combat skin dehydration.

  Dehydrated skin is characterised by a loss of radiance and feelings of discomfort. In some cases, it may flake and present a rough texture. Therefore, it is important to care for your skin and hydrate it regularly. A study has shown that astaxanthin can help to improve skin hydration. Over three weeks, eleven volunteers used a cream formulated with astaxanthin. The results showed a significant increase in the hydration levels of the stratum corneum in all participants, as evidenced by instrumental measurements.

  While the exact mechanism of action for astaxanthin has not been specified, the following hypothesis can be proposed: by stabilising cellular membranes and limiting lipid peroxidation, astaxanthin could potentially contribute to strengthening the skin barrier, thereby reducing transepidermal water loss. Further studies, conducted on larger panels, are still required to confirm whether astaxanthin's moisturising effect is direct or indirect.

• Astaxanthin to soothe skin inflammations.

  Astaxanthin also has anti-inflammatory activity that could help soothe skin irritations. It has been shown that astaxanthin inhibits the activity of IκB kinase, a complex controlling the activation of the transcription factor NF-κB. The latter is involved in the regulation of many pro-inflammatory cytokines, such as IL-1β, IL-6 or TNF-α. Astaxanthin also reduces the expression of matrix metalloproteinases, enzymes not only involved in collagen degradation, but also in the propagation of inflammation in skin tissues. These various actions of astaxanthin suggest that it could help soothe mild skin irritations, a hypothesis that would be interesting to verify in clinical studies.

  Note : Numerous studies have highlighted the anti-inflammatory properties of astaxanthin in humans, but they all involved oral administration.

While astaxanthin is most commonly found in skincare products, it may also have potential benefits for hair, particularly in limiting hair loss. Indeed, this pigment is a natural inhibitor of 5-alpha-reductase, an enzyme that converts testosterone into dihydrotestosterone (DHT). DHT is involved in the miniaturisation of hair follicles found in alopecia. An in vitro study showed that astaxanthin, at a concentration of 300 µg/mL, inhibited the activity of 5-alpha-reductase by 98%. However, caution is advised as these results are limited to cellular models and no clinical studies have yet evaluated the effects of astaxanthin on hair loss in humans.

Furthermore, the antioxidant activity of astaxanthin could also help to prevent the greying of hair. Indeed, by neutralising free radicals, astaxanthin could contribute to protecting the cells of the hair follicle, whose oxidative stress accelerates degeneration. This stress is also involved in the gradual discolouration of hair by affecting melanocytes, the cells responsible for pigmentation. Thus, it can be extrapolated that astaxanthin, due to its strong antioxidant potential, could potentially help slow down the onset of grey hair, although this has not yet been experimentally confirmed.

When applied topically, the astaxanthin is an active ingredient generally well tolerated and does not present any particular risk.

However, even though astaxanthin is suitable for all skin types, there is no such thing as zero risk and it is possible to be allergic to astaxanthin. Indeed, some skin types may naturally be sensitive to the Hematococcus pluvialis, the unicellular algae that is a primary natural source of astaxanthin. Therefore, when first using a product containing it, as with any new product, it is recommended to conduct a test to ensure that the skin tolerates this active ingredient well. Apply a small amount of the product to the inside of your elbow or wrist and wait 24 to 48 hours. If no redness, irritation or itching appears, you can begin to incorporate it into your skincare routine.