Can a beauty supplement make hair thicker? new study investigates

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Participants must meet all of the following criteria: 1. Adults aged 21-50 years. 2. Generally healthy, as determined by medical history, physical exam, and available laboratory results from Visit 1 (Day -1/Day 0). 3. Self-perceived thinning hair associated with diet, stress, or hormonal influences. 4. Willingness to maintain the usual hair care routine, including shampoo frequency, and consistent haircut/color during the study. 5. Willingness to take the study supplement daily as instructed. 6. Willingness to avoid major changes in diet, medications, or exercise during the study and to notify the clinic of any changes. 7. Willingness to undergo all required assessments, including physical exam, vital signs, hematology, urine pregnancy test (if applicable), scalp exam, hair photography, and completion of the Hair Shedding Diary. 8. Fitzpatrick skin types I-IV. 9. Ability and willingness to provide written informed consent. Exclusion Criteria: Participants will be excluded if they meet any of the following: 1. Known allergy or intolerance to any component of the study supplement (e.g., biotin, keratin, collagen, fish/seafood, acerola). 2. Known allergy or sensitivity to hair care products specified for use in the study. 3. Pregnant, breastfeeding, or planning to become pregnant during the study period. 4. Significant stress event (e.g., death in family, miscarriage) within the past 6 months. 5. Participation in another clinical study concurrently. 6. Initiation of hormonal therapy within the past 6 months (stable use for at least 6 months allowed). 7. Current use of light therapy for hair loss. 8. Use of minoxidil or other hair growth medications within the last 3 months. 9. Current use of biotin, keratin, collagen, or similar supplements. 10. Use of prescription medications known to affect hair growth within the last 6 months. 11. Hair disorders other than self-perceived thinning hair (e.g., alopecia areata, scarring alopecia, androgenetic alopecia, telogen effluvium). 12. Uncontrolled chronic diseases (e.g., diabetes, hypertension, thyroid disorders). Stable, well-controlled conditions may be allowed at the investigator's discretion. 13. Active hepatitis, immune deficiency, human immunodeficiency virus (HIV) infection, or autoimmune disease. 14. Active dermatologic conditions that may interfere with assessments or increase risk (e.g., severe seborrheic dermatitis, psoriasis, advanced skin cancer).