The main objective of this study is, after collecting serum enriched with metabolites of interest resulting from the ingestion of the Kera-Diet® food supplement, to determine the influence of these sera enriched with circulating metabolites (versus naïve sera) on the behavior of human cell cultures, placed under stress conditions or not, in order to evaluate the benefit of these metabolites in maintaining cellular functions.

Main inclusion Criteria:

• Liver function tests within reference norms.
• Kidney function tests within reference norms.
• Complete blood count (CBC) within reference norms.
• C-reactive protein (CRP) within reference norms.
• Blood pressure compatible with study requirements.
• Non-smoker or occasional smoker (max 5 cigarettes/day or max 10 ml per week of e-liquid with a nicotine concentration of 3 mg/ml).
• Max 5 hours of intense sports per week.
• Weight ≥ 60 kg.
• BMI between 20 and 28 kg/m² (exclusive).

Main exclusion Criteria:

• Any type of vaccination within the past month.
• Alcohol consumption exceeding WHO standards (Sup. 3 drinks per day for men).
• Ongoing treatment (medication, dietary supplement, or probiotic) and within the four weeks prior to inclusion.
• Known pathology (including seasonal).
• Allergy to the study product, particularly to keratin or certain amino acids.
• Individuals following a diet unsuitable for the study (e.g., vegetarian, vegan, or plant-based diets).
• Change in eating habits within the 4 weeks prior to inclusion.
• Medical and/or surgical history deemed incompatible with the trial by the investigator or their representative.