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Randomized Controlled Trial
. 2025 Jan;24(1):e16626.
doi: 10.1111/jocd.16626. Epub 2024 Oct 4.

The Effects of an Oral Supplementation of a Natural Keratin Hydrolysate on Skin Aging: A Randomized, Double-Blind, Placebo-Controlled Clinical Study in Healthy Women

Francesco Tursi  1 , Vincenzo Nobile  2 , Enza Cestone  1 , Ileana De Ponti  1 , Anne Lepoudere  3 , Renaud Sergheraert  3 , Jean-Philippe Soulard  3
Affiliations
Randomized Controlled Trial

The Effects of an Oral Supplementation of a Natural Keratin Hydrolysate on Skin Aging: A Randomized, Double-Blind, Placebo-Controlled Clinical Study in Healthy Women

Francesco Tursi et al. J Cosmet Dermatol. 2025 Jan.

Abstract

Background: Keratin hydrolysates are active components used in food supplements to alleviate aging signs on skin, hair, and nails.

Aims: This randomized, double-blind, placebo-controlled study evaluates a novel keratin hydrolysate obtained from poultry feathers. This feather keratin hydrolysate (FKH) results in a characteristic mix of free L-amino acids (≥ 83.5%). FKH was administered as a food supplement to a panel of adult women showing aging physiological signs.

Methods: Participants were randomly assigned in three groups to receive daily dosages of 500 or 1000 mg of FKH or placebo for 90 days. Parameters of skin roughness, wrinkle features, deep skin moisturization, skin maximum elongation and elasticity, skin thickness, skin anisotropy, skin density, gloss of skin, hair and nails, and nail hardness were evaluated. Subjects also answered a questionnaire related to the treatment efficacy perception.

Results: Both FKH treatments showed a significant improvement of all parameters compared to day 0 and to placebo, with an exception for fiber anisotropy and fiber density which showed a significant improvement compared to day 0 and a tendency to improve compared to placebo. These measurements were bolstered by the results of a self-assessment questionnaire, showing an overall set of positive answers for both treatments compared to placebo.

Conclusions: Oral supplementation of FKH for 90 days is associated with an improvement in the appearance of facial skin, hair, and nails. This study highlights the benefits of free L-amino acids mix as potential aminobiotics and not just as building blocks of proteins, suggesting a new perspective of nutricosmetic food.

Keywords: aminobiotics; anti‐aging; extensive hydrolysis; free amino acids; keratin hydrolysates.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Amino acids profile expressed in amino acid content (in % w/w) of FKH product.
FIGURE 2
FIGURE 2
Participant flow chart.
FIGURE 3
FIGURE 3
Effect of treatments on wrinkle depth (A), wrinkle length (B), and wrinkle area (C). Results are expressed as mean ± SEM of the respective parameters and as % of variation versus D0 (Δ%45 or Δ%90). Intragroup* and intergroup# (actives vs. placebo as Δ%45 or Δ%90) statistical analyses are reported as *,# p < 0.05, **,## p < 0.01, and ***,### p < 0.001.
FIGURE 4
FIGURE 4
Effect of treatments on epidermis thickness (A), fiber anisotropy (B), and fiber density (C). Results are expressed as mean ± SEM of the respective parameters and as % of variation D90 versus D0 intragroup* and intergroup# (actives vs. placebo as Δ%90); statistical analyses are reported as *,# p < 0.05, **,## p < 0.01, and ***,### p < 0.001.
FIGURE 5
FIGURE 5
Self‐assessment questionnaire to questions referring to the hair: Mean percentage of positive answers (completely agree + agree).
FIGURE 6
FIGURE 6
Self‐assessment questionnaire to questions referring to the nails: Mean percentage of positive answers (completely agree + agree).
FIGURE 7
FIGURE 7
Self‐assessment questionnaire to questions referring to the product satisfaction: Mean percentage of positive answers (completely agree + agree).
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References

    1. Bai H. and Graham C., “Introduction: Skin,” Yale Journal of Biology and Medicine 93, no. 1 (2020): 1–2.
    1. Binic I., Lazarevic V., Ljubenovic M., Mojsa J., and Sokolovic D., “Skin Ageing: Natural Weapons and Strategies,” Evidence‐Based Complementary and Alternative Medicine 2013 (2013): 1–10. - PMC - PubMed
    1. Cao C., Xiao Z., Wu Y., and Ge C., “Diet and Skin Aging From the Perspective of Food Nutrition,” Nutrients 12 (2020): 870. - PMC - PubMed
    1. Strasser B., Volaklis K., Fuchs D., and Burtscher M., “Role of Dietary Protein and Muscular Fitness on Longevity and Aging,” Aging and Disease 9 (2018): 119–132. - PMC - PubMed
    1. Thompson K. G. and Kim N., “Dietary Supplements in Dermatology: A Review of the Evidence for Zinc, Biotin, Vitamin D, Nicotinamide, and Polypodium,” Journal of the American Academy of Dermatology 84, no. 4 (2021): 1042–1050, 10.1016/j.jaad.2020.04.123. - DOI - PubMed

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