AHK-Cu vs GHK-Cu: Which Peptide Is Better for Skin?
GHK-Cu wins this on evidence. It has human wound and skin data behind it. AHK-Cu has one unreplicated dish study and no human trial at all. Use GHK-Cu…
- AHK-Cu
- GHK-Cu
Best Interventions for Hair and Nail Health, Ranked by Evidence
Every intervention Outliyr has scored for hair and nail health, ranked by its BioHarmony score for this use case rather than its overall rating. The number beside each name is how well that one thing works for hair and nail health; the tier beside it is what it is worth once safety, cost and effort are counted across everything else.
19 of 92 evaluated interventions score 3.0+ out of 10 for hair and nail health · 4 comparisons
Ranked for Hair and Nail Health
Category
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Red Light Therapy
Lanzafame 2013 reported a 35% hair-count increase versus 2% sham after 16 weeks in androgenetic alopecia. Red Light Therapy fits hair better than nails because follicles are living targets with mitochondrial and…
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Spermidine
Schwarz 2022 supports direction more than certainty. The existing rationale points to this narrower claim: this verified source randomized 100 participants and found a spermidine-based supplement improved hair follicle cycling markers over…
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Glycine
Holecek 2025 anchors the most relevant signal. Glycine fits hair nail because glycine participates in sleep signaling, glutathione, collagen, methylation, and nervous-system balance, depending on the endpoint. The score stays bounded because…
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Essential Amino Acids
Wittholz 2024 reports Systematic review found heterogeneity high enough that planned meta-analysis was not possible. Hughes 2024 points in the same direction, but route, dose, baseline status, and outcome tracking decide whether…
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TB-500 (Thymosin Beta-4 Fragment)
Hair-follicle support rests mainly on animal and mechanistic evidence. Philp 2004 title-matches thymosin beta-4 effects on hair-follicle development, but the audit flagged the old PMID as unrelated, so no PubMed identifier is…
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Collagen Peptides
Hexsel 2017 reported improved brittle nails in an open-label trial. Hair evidence is much thinner and should not be inferred from nail or skin outcomes. That makes Collagen Peptides more defensible when…
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Metformin
Metformin is not recognized as a primary agent for stimulating hair growth or strengthening nails, and the evidence rests on secondary outcomes rather than dedicated trials. The mechanism involves lowering circulating insulin,…
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Ca-AKG (Calcium Alpha-Ketoglutarate)
Shahmirzadi 2020 anchors the strongest signal. The existing rationale points to this narrower claim: No hair or nail evidence. Keep neutral unless dermatology trials emerge. That does not make Ca-AKG (Calcium Alpha-Ketoglutarate)…
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GHK-Cu
GHK-Cu is common in hair products and has follicle-adjacent mechanisms, but direct human hair-regrowth trial support is much weaker than minoxidil or red light therapy. Pickart 2018 reviews follicle and skin regeneration…
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Rapamycin
INSUFFICIENT_EVIDENCE for hair or nail benefit; use mainly as an adverse-change watch item rather than a target.
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NAC (N-Acetylcysteine)
The trichotillomania (hair-pulling) data per Grant 2009 is about compulsive behavior, not hair growth; there is no evidence NAC improves hair or nail quality directly.
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Whole-Body Vibration
No evidence. Whole-body vibration should not be marketed for hair or nail growth.
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Thymosin Beta-4 (Tβ4)
Hair growth claims for Tβ4 are entirely preclinical, with rodent and in vitro evidence that Tβ4 activates hair-follicle stem cells, per Gao 2015. No peer-reviewed human clinical trial of native Tβ4 for…
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Semaglutide
Hair shedding can occur from rapid weight loss, caloric deficit, or micronutrient gaps, so hair and nail effects skew negative.
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Tongkat Ali
The androgenic mechanism cuts both ways. Tongkat Ali may support body-hair androgen tone but could worsen androgenetic alopecia in DHT-sensitive men.
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Vitamin C (Ascorbic Acid)
Through its collagen-cofactor role, adequate vitamin C supports the connective tissue underlying hair follicles and nail beds, and deficiency produces corkscrew hairs and brittle, fragile tissue that reverse on repletion. Beyond correcting…
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Astaxanthin
Skin and microcirculation overlap may help appearance indirectly. No strong hair or nail endpoint evidence.
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Hyaluronic Acid
Scalp and skin hydration overlap may help appearance indirectly, but there is no strong hair-growth or nail-strength endpoint evidence for oral or topical HA.
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C15 (Pentadecanoic Acid)
No published C15:0 trial has measured hair count, hair shedding, nail growth, or nail strength. The follicle and nail-matrix extrapolation from cell membranes is speculative and not supported by Robinson 2024 (Robinson…
Nothing matches those filters.
What each one costs
Monthly out-of-pocket cost at the most accessible legitimate channel, at the dose the score was given for. 6 of 19 are not priced yet; those cells are left blank rather than guessed.
| Intervention | Monthly cost | At dose | How you get it |
|---|---|---|---|
| Red Light Therapy | $17–$43 | 10-20 min at 6-12 inches, full chest/face/back rotation | Over the counter |
| Spermidine | $40–$90 | 1-3 mg/day oral WGE | Over the counter |
| Glycine | $2–$3 | 3 g oral glycine | Over the counter |
| Essential Amino Acids | Not priced yet | ||
| TB-500 (Thymosin Beta-4 Fragment) | Not priced yet | ||
| Collagen Peptides | $8–$40 | 2.5-10 g hydrolyzed collagen peptides | Over the counter |
| Metformin | $4–$30 | 500 mg with dinner for 1 week, then 500 mg twice daily for 1 week, then increase by 500 mg/week toward 1000 mg twice daily as tolerated | Prescription |
| Ca-AKG (Calcium Alpha-Ketoglutarate) | $15–$30 | 1 g/day generic Ca-AKG oral | Over the counter |
| GHK-Cu | $30–$100 | 0.5-3% topical serum or cream | Over the counter |
| Rapamycin | $15–$50 | 3 mg | Prescription |
| NAC (N-Acetylcysteine) | $5–$15 | 600 to 1,200 mg/day | Over the counter |
| Whole-Body Vibration | $50–$100 | 30 Hz, roughly 0.3g, 10-20 min standing | Over the counter |
| Thymosin Beta-4 (Tβ4) | Not priced yet | ||
| Semaglutide | $199–$349 | 0.25 mg weeks 1 to 4, 0.5 mg weeks 5 to 8, 1.0 mg weeks 9 to 12, 1.7 mg weeks 13 to 16, 2.4 mg week 17 onward | Prescription |
| Tongkat Ali | $20–$40 | 200 mg/day Physta standardized extract | Over the counter |
| Vitamin C (Ascorbic Acid) | Not priced yet | ||
| Astaxanthin | Not priced yet | ||
| Hyaluronic Acid | Not priced yet | ||
| C15 (Pentadecanoic Acid) | $40–$50 | 200 mg/day | Over the counter |
Comparisons that judge hair and nail health
Head-to-head reports and category rankings that name a winner on this use case.
Colostrum vs Collagen Peptides: Which Should You Buy?
These two get sold as the same thing, a scoop for gut and skin, and they share almost no mechanism. Colostrum is a gut and immune product: gut…
- Colostrum
- Collagen Peptides
HBOT vs Red Light Therapy: Which Is Better for Recovery?
Buy the panel. Red light therapy scores 7.5–8.0/10 against HBOT's 5.5–6.0/10, costs $17 to $43 a month against $3,000 to $6,000, and does not lose a single use…
- Hyperbaric Oxygen Therapy
- Red Light Therapy
Spermidine vs Urolithin A: Which Is Better for Longevity?
Spermidine scores 7.5–8.0/10 and urolithin A 6.5–7.0/10, and they clean up different messes. Spermidine drives broad autophagy: autophagy 8.0/10, cardiovascular 7.8/10, longevity 7.5/10. Urolithin A drives selective mitophagy…
- Spermidine
- Urolithin A
Questions about hair and nail health
What scores highest for hair and nail health?
Red Light Therapy, at 8.0–8.5 out of 10 for hair and nail health. Lanzafame 2013 reported a 35% hair-count increase versus 2% sham after 16 weeks in androgenetic alopecia.
What is the cheapest thing that works for hair and nail health?
Of the top-scoring options, Glycine is the least expensive at about $2 a month, scoring 6.5–7.0 out of 10 for hair and nail health.
What should I be careful with for hair and nail health?
C15 (Pentadecanoic Acid) scores 3.0–3.5 out of 10 for hair and nail health but only 3.0–3.5 overall, landing in the caution tier once safety, side effects, cost and effort are counted.
How many interventions has Outliyr scored for hair and nail health?
19 of the 92 interventions evaluated for hair and nail health score 3.0 out of 10 or better, which is the cut-off for appearing on this page.
