The Nutra Harmony "Biotin, Collagen and Keratin Beauty Complex" is an oral food/dietary supplement specifically designed to Promote hair growth for people suffering from temporary thinning hair. The main goal of this clinical trial is to evaluate the efficacy of two different doses of the study supplement (with 5,000 mcg vs 10,000 mcg biotin). A product formula with 10,000 mcg of biotin per serving was clinically tested and demonstrated results in strengthening hair and increasing hair thickness by promoting the growth of terminal hairs in subjects aged 21 to 50 years, with self-perceived thinning hair associated with poor diet, stress, and hormonal influences, compared with the placebo tablet.

This study is a two-arm, parallel-group, randomized, single-blind, dose-comparison trial designed to evaluate the efficacy of two doses of the study supplement (5,000 mcg vs 10,000 mcg biotin) in adults with self-perceived temporary hair thinning. The trial is powered to detect meaningful differences in hair growth between the two dose groups over a 3-month treatment period. Total trial duration for participants is approximately 3 months, with the treatment period lasting 90 days following randomization. Approximately 40 males and females, aged 21 to 50, who met all eligibility criteria, were randomized in a 1:1 ratio to receive either the 5,000 mcg or 10,000 mcg biotin dose of the study supplement.

Within the study, there were a total of 4 site visits for each participant, during which the following procedures were performed:

Visit 1: Screening/Randomization (Day -1 / Day 0) Screening assessments will be performed on Day -1. Hematology results required for eligibility evaluation will be obtained on the following day. Randomization and study drug dispensing will occur on Day 0, only after all inclusion/exclusion criteria are confirmed, including availability of laboratory results. No additional assessments will be performed on Day 0.

The following procedures will take place:

1. Signing the informed consent form (ICF);
2. Demographics recording;
3. Height and weight assessment;
4. Vital signs: pulse, systolic blood pressure (SBP), and diastolic blood pressure (DBP) after 10 minutes of rest;
5. Medical history and current medications;
6. Hematology sample collection;
7. Urine pregnancy test (for women of childbearing potential);
8. Basic physical examination: general appearance; skin, hair, nails; cardiovascular; respiratory; abdomen;
9. Dermoscopic photographs of the target scalp area (for hair count and follicle evaluation);
10. Standardized digital photographs of the target scalp area (for overall hair appearance and coverage);
11. Quality of Life Questionnaire (QoL);
12. Instruction for Hair Shedding Diary (participant-reported for the period since last visit);
13. Randomization (Day 0): participants will be randomized in a 1:1 ratio to receive one of two doses of the study product;
14. Study product dispensing (Pack 1).

Visit 2: (Day 30±3), Visit 3: (Day 60±3)

The following procedures will take place:

1. Update medical history and concomitant medications;
2. Adverse events review;
3. Hair shedding diary review (overall for the previous period);
4. Hair count in defined control points of the scalp;
5. Study product dispensing (Pack 2 at Day 30, Pack 3 at Day 60).

Visit 4: (Day 90, End of Study)

The following procedures will take place:

1. Vital signs: pulse, systolic [SBP] and diastolic [DBP] blood pressure (after 10 minutes resting);
2. Hematology;
3. Hair shedding diary review (final period);
4. Dermoscopic photographs of the target scalp area (for hair count and follicle evaluation);
5. Standardized digital photographs of the target scalp area (for overall hair appearance and coverage);
6. Hair count in defined control points;
7. Quality of Life Questionnaire;
8. Self-assessment Questionnaire. No further follow-up is required unless unresolved adverse events (AEs) exist.

The effectiveness of the treatment will be evaluated by comparing the increase in hair growth in study supplement-treated subjects, defined as the change in hair area from baseline and the count of hair at several control points relative to baseline, between the two dosage groups.

Additional effectiveness assessments included hair shedding counts during hair washing (shampooing) in subjects treated with the supplement containing 5,000 mcg of biotin per serving, compared with subjects treated with the supplement containing 10,000 mcg of biotin per serving, as well as changes in quality-of-life and self-assessment questionnaire scores during and after the study.

The tolerability of the studied supplement was assessed on the basis of the patient's subjective complaints, the presence and severity of adverse reactions/side effects, the data of the patient's examination, and laboratory examination.

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).

IPD (Individual Participant Data) will not be shared, as information about each participant is strictly confidential. Only aggregated information regarding the effectiveness and safety of the investigated supplement among all study participants will be shared within the framework of statistical data.