The Effects of the Oral Supplementation with a Natural Keratin Hydrolysate (Kera-Diet®) on Hair and Nails: Randomized, Placebo and Benchmark-Controlled Clinical Trial on Healthy Females

*Corresponding author: Vincenzo Nobile, Francesco Tursi, Enza Cestone, Renaud Sergheraert and Joel Duperray*

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original research


Telogen effluvium (TE) and its acute form (aTE) are two of the commonest occurrences in a trichology clinic, with patients claiming excessive hair shedding. ATE can occur in people of any age and ethnicity and is considered to be a quite common condition in either sex even if women are more likely to have a lowered quality of life and restricted social contacts as compared to men as a result of hair loss. Brittle nail syndrome (BNS) is a common condition affecting up to 20% of the population, especially women over 50 years of age. Nails affected by BNS appear ragged, thin, and dull. The clinical features of BNS include horizontal splits within the nail plate (onychoschizia) and increased longitudinal ridging or splitting (onychorrhexis). In BNS oral supplementation, trace elements and amino acids (especially L-Cystine) have been reported to be useful to ameliorate the nail plate condition.
We hypothesized that a nutritional approach, with nutrients of which the composition is close to the human keratin, could be effective to decrease hair loss during telogen effluvium and to improve brittle nails condition. At this purpose, a clinical study was designed to investigate the efficacy of a natural keratin hydrolysate obtained from a non-human source (feathers) on both aTE and BNS.
The in vivo effects of a natural keratin hydrolysate, Kera-Diet® (KD) upon human hair and nails condition was tested in a randomized, double-blind, parallel-group, benchmark (BE) and placebo (PL) controlled study involving 60 women during 90 days. In all subjects, Anagen/Telogen hair, hair volume and density, pull test, global photography, hair and nails brightness, and nail plate
growth were measured at baseline and after 45 and 90 days of products use. A self-assessment test was carried out at the end of the study.
With the KD treatment group, hair density, percentage of hair in anagen phase, hair and nails brightness, and nails growth were significantly increased compared to PL treatment group. Interestingly, with this same group, the diagnosis of aTE by pull testing was negative from 45 days. The efficacy of KD was equal to or greater than PL treatment group.
In this study, we demonstrated that daily oral administration of 1000 mg during 3 months of a natural extensively keratin hydrolysate, Kera-Diet®, associated to trace elements and specific vitamins was effective to improve both hair and nails condition. Furthermore, it demonstrates the role of nutrients in both aTE and BNS.
Keratin hydrolysate; Oral supplementation; Telogen effluvium; Hair growth; Brittle nail syndrome; Onychoschizia; Clinical study.