Here are some studies about dietary astaxanthin and photoaging prevention
Conclusion: Technical article explaining how astaxanthin protects against photodamage by reducing expression of matrix metalloproteinases, the enzymes responsible for post-UV exposure skin collagen breakdown.
Conclusion: Randomized control trial tested the effectiveness of oral astaxanthin for skin photoprotection. 65 women were split into three groups where they were given either a placebo, 6mg astaxanthin supplement (low dose), or 12mg astaxanthin supplement (high dose) daily for 4 months. Skin samples were taken from the participants and studied in vitro for changes in UV-response. The skin sample observations found that astaxanthin was effective for reducing expression of matrix-metalloproteinases (MMPs, the enzymes responsible for skin collagen breakdown).
Enriched Astaxanthin Extract from Haematococcus pluvialis Augments Growth Factor Secretions to Increase Cell Proliferation and Induces MMP1 Degradation to Enhance Collagen Production in Human Dermal Fibroblasts (2016)
Conclusion: In vitro study found that application of astaxanthin to human skin samples reduces expression of matrix metalloproteinases, the enzymes responsible for post-UV exposure skin collagen breakdown.
Conclusion: Two studies. First, a study of 30 women found that consuming an astaxanthin supplement daily for 8 weeks effectively reduced facial skin wrinkles. Second, a randomized placebo-controlled trial of 36 men found that daily supplementation of astaxanthin for 6 weeks effectively reduced facial skin wrinkles. Subjects in both studies also enjoyed an improvement in facial skin elasticity and reduction of transepidermal water loss.
Conclusion: Randomized, placebo-controlled trial split a group of 49 middle-aged women to receive either a 4mg dietary astaxanthin supplement or placebo daily for 6 weeks to test for efficacy at improving skin elasticity and wrinkles. At the end of the study, changes in skin health were determined using subjective questionnaires, dermatologist evaluation, dermal phase meter, and micro-photography. More than half of those in the astaxanthin group reported improvements in their skin dryness, skin moisture, roughness, elasticity, and wrinkles – whereas the placebo group did not. These positive effects in the treatment group were also observed by dermatologist evaluation, with instrument measuring, and photography observation.
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