Best for Skin & Hair

Collagen peptides have demonstrated consistent, clinically meaningful improvements in skin hydration, elasticity, and wrinkle reduction across multiple well-designed human RCTs. Evidence is strong for skin aging parameters, though studies are primarily short-term (8-12 weeks) and predominantly conducted in women.

Probiotics demonstrate clinically meaningful efficacy for skin conditions, particularly psoriasis and atopic dermatitis in both adults and infants, supported by multiple meta-analyses and RCTs showing consistent reductions in disease severity scores and improved quality of life.

Pycnogenol demonstrates strong efficacy for improving skin and hair health in humans, with multiple RCTs showing clinically meaningful improvements in hair density, skin elasticity, hydration, and photoaging markers. Effects are supported by both clinical outcomes and molecular evidence of increased collagen and hyaluronic acid expression.

Ashwagandha shows probable efficacy for skin and hair health based on multiple human RCTs demonstrating improvements in hair density, hair loss reduction, skin hydration, and quality of life metrics. However, evidence is limited by small sample sizes, short study durations (60-75 days), and lack of independent replication by different research groups.

Melanotan-1 (afamelanotide) demonstrates probable efficacy for skin pigmentation and related photoprotection in humans, with consistent positive results across multiple human studies. However, evidence is limited to small-to-moderate sample sizes and primarily addresses disease treatment (vitiligo, photosensitivity disorders) rather than cosmetic hair/skin enhancement.

Cerebrolysin demonstrates emerging evidence for hair repigmentation in humans based on a small observational case series (n=5), with mechanistic support showing reactivation of melanocyte markers. However, evidence is limited to a single human observational study with no RCTs, placebo controls, or independent replication.

GLP-1 receptor agonists show probable efficacy for improving inflammatory skin conditions (psoriasis, hidradenitis suppurativa) through anti-inflammatory mechanisms, supported by multiple human observational studies and small RCTs. However, evidence is limited by small sample sizes, short study durations, and mixed findings on hair loss and facial aging.

NAC shows probable efficacy for hair and skin conditions, particularly for body-focused repetitive behaviors (trichotillomania, skin-picking) and wound healing in diabetic models. Evidence is moderate but limited by small human sample sizes and lack of large-scale RCTs.

Zinc supplementation shows probable efficacy for several skin and hair conditions, particularly acne and alopecia areata, with consistent evidence of lower serum zinc levels in affected patients. However, human evidence comes primarily from small RCTs and observational studies; larger, independently replicated trials are needed to establish definitive clinical benefit.

Curcumin shows probable efficacy for skin health in humans, particularly for inflammatory skin conditions like pruritus and psoriasis, supported by 3 human RCTs and 2 systematic reviews. However, evidence is limited by small sample sizes, short study durations, and lack of independent replication across diverse populations.

Resveratrol shows probable efficacy for skin health based on 3 human RCTs demonstrating improvements in wrinkle reduction, skin elasticity, and aging markers, but evidence is limited by small sample sizes, short study durations, and inconsistent methodologies across trials.

CoQ10 shows probable efficacy for skin aging when taken orally or applied topically, with one well-designed RCT demonstrating reduced wrinkles and improved skin smoothness over 12 weeks. However, evidence remains limited to a small number of human studies with modest sample sizes and inconsistent findings across skin parameters.

Melatonin shows probable efficacy for skin and hair health based on 3 human RCTs demonstrating improvements in atopic dermatitis severity and sleep quality, plus mechanistic evidence from animal studies. However, efficacy is not conclusively proven due to small sample sizes, short treatment durations, and limited independent replication for hair loss specifically.

Milk thistle (silymarin) shows probable efficacy for skin health based on 2 human RCTs and 4 observational studies, with demonstrated effects on vitiligo repigmentation, acne severity, and UV-induced skin damage. However, evidence remains limited by small sample sizes and lack of independent replication across different research groups.

Black seed oil (Nigella sativa) shows probable efficacy for vitiligo and wound healing in humans, supported by multiple small clinical studies and consistent mechanistic evidence. However, efficacy is not conclusively proven due to limited RCT data, small sample sizes, and lack of independent replication across study groups.

Aged garlic extract shows probable efficacy for skin and wound healing based on multiple human RCTs demonstrating improved microcirculation and tissue perfusion, supported by animal studies showing enhanced wound closure and fibroblast protection. However, evidence is limited to indirect skin benefits (improved blood flow) rather than direct skin or hair health outcomes.

Saw palmetto shows probable efficacy for hair growth and reduction of hair shedding in androgenetic alopecia, supported by multiple human studies with consistent positive results. However, evidence quality is limited by small sample sizes, heterogeneous study designs, and lack of independent replication across research groups.

Vitamin C shows probable efficacy for skin and hair health through collagen synthesis and antioxidant mechanisms, supported by multiple human studies and consistent mechanistic evidence. However, evidence remains limited to small RCTs, short durations, and topical formulations with variable bioavailability—efficacy is not conclusively proven across diverse populations.

Vitamin B Complex shows probable efficacy for hair growth and skin health in humans, with multiple RCTs demonstrating modest improvements in hair density and quality. However, evidence remains limited by small sample sizes, short study durations, and inconsistent effect sizes across studies.

Vitamin B12 shows probable efficacy for skin-related conditions, particularly vitiligo and hyperpigmentation associated with B12 deficiency, supported by multiple human studies. However, evidence is limited by small sample sizes, lack of rigorous RCT designs for most skin outcomes, and some concerning findings linking B12 supplementation to increased cancer risk in certain populations.

Boswellia serrata shows probable efficacy for skin health based on multiple human RCTs demonstrating improvements in photoaging, acne, psoriasis, and eczema. However, evidence is limited by small sample sizes, short treatment durations, and lack of independent replication across most indications.

Pomegranate extract shows probable efficacy for skin health parameters including wrinkle reduction and improved skin biophysical properties in humans, supported by multiple RCTs with consistent positive results but limited sample sizes and short study durations.

Olive leaf extract shows probable efficacy for skin health through multiple small human studies demonstrating improvements in hydration, wrinkles, and wound healing, though evidence is limited by small sample sizes, lack of large RCTs, and inconsistent mechanistic findings.

MSM shows probable efficacy for skin aging in humans based on one moderate-quality observational study demonstrating improvements in wrinkles, skin firmness, and elasticity at 3 g/day. Evidence for hair quality is limited to one small animal study in kittens with marginal improvements.

Bromelain shows probable efficacy for skin health based on 2 small human RCTs and supportive animal/in-vitro data, but evidence remains limited by small sample sizes and short study durations. Clinical benefit appears most established for inflammatory skin conditions and wound healing.

Cistanche shows probable efficacy for hair growth based on 2 human RCTs demonstrating statistically significant improvements in hair density and diameter, though sample sizes are modest (n=45) and results have not been independently replicated.

Lemon balm demonstrates probable efficacy for skin health through multiple human RCTs and mechanistic studies, with evidence of anti-wrinkle effects, improved skin barrier function, and psoriasis symptom reduction. However, sample sizes remain modest and long-term durability is unclear.

Rapamycin/sirolimus shows probable efficacy for skin health, primarily through reducing senescence markers and improving photoaging in a small human RCT, with additional support from multiple dermatological case series and observational studies. However, evidence is limited by small sample sizes, lack of independent replication, and focus on specific skin conditions rather than hair.

Oral hyaluronic acid shows probable efficacy for skin hydration, elasticity, and wrinkle reduction in humans, supported by a 2025 meta-analysis of 7 RCTs. However, evidence is limited by small sample sizes, heterogeneity across studies, and lack of independent replication by multiple research groups.

Butyrate shows probable benefit for skin health through gut microbiota modulation and barrier function strengthening, supported by multiple human observational studies and mechanistic research. However, efficacy is not definitively proven due to limited human RCTs (only 1 small trial) and reliance on indirect markers rather than clinical skin outcomes.

PQQ demonstrates probable efficacy for skin health based on multiple human observational studies and consistent animal models, but evidence remains limited by lack of RCTs, small sample sizes, and short study durations. Human data shows improvements in skin texture, tone, and photodamage appearance, but clinical significance remains modest.

DMAE demonstrates probable efficacy for improving skin firmness and reducing fine wrinkles in humans based on 2 RCTs, but evidence is limited by small sample sizes (n=25-30), short durations (4-16 weeks), and lack of independent replication. Results are consistent across available human studies but not conclusive.

HMB shows probable benefits for skin health when combined with arginine and glutamine in humans, with one RCT demonstrating improvements in skin elasticity, brightness, and wrinkles. However, evidence is limited to a single small pilot RCT and several animal/mechanistic studies; efficacy for skin and hair specifically remains incompletely proven.

BPC-157 shows promising effects for skin wound healing in animal models, accelerating closure of burns, cuts, and complex wounds. However, no human trials exist for skin/hair applications.

Creatine monohydrate has not been proven to improve skin or hair health in humans. The single well-designed human RCT directly testing hair outcomes found no effects on hair density, follicle count, or DHT levels, while mechanistic evidence from cell and animal studies is preliminary and not translatable to clinically meaningful skin/hair benefits.

Animal studies suggest TB-500 promotes wound healing and hair follicle development, but human evidence is extremely limited with no completed RCTs for skin/hair applications.

GHK-Cu shows consistent mechanistic promise for hair and skin health in animal and in-vitro studies, but human evidence remains limited to small observational trials without controls. Efficacy is plausible but not proven in humans.

KPV shows anti-inflammatory properties in animal models and review-based theoretical mechanisms, but there are zero human clinical trials demonstrating efficacy for skin/hair health. Evidence is preliminary and mechanism-focused rather than outcome-proven.

LL-37 shows mechanistic promise for skin and hair health through antimicrobial, wound-healing, and immunomodulatory pathways, but human efficacy evidence is limited to observational studies and one small RCT. Most supporting data comes from animal models and in-vitro research.

Kisspeptin shows promise for skin and hair health based on one in-vitro study demonstrating anti-aging effects, and observational evidence linking kisspeptin to body hair growth in a hormonal deficiency case. However, no human clinical trials exist for skin/hair benefits, and evidence remains largely mechanistic or anecdotal.

GHRP-6 shows promise for skin and hair health through mechanistic studies, particularly in wound healing and collagen synthesis, but evidence is limited to 1 human observational study and animal models with no rigorous human RCTs demonstrating efficacy for skin or hair.

GDF-11 shows consistent effects on skin wound healing and anti-aging properties in animal models, with emerging evidence from in vitro studies of skin cells. However, no rigorous human RCTs exist; efficacy in humans remains plausible but unproven.

VIP is a neuropeptide implicated in neurogenic inflammation and skin pathology (psoriasis, atopic dermatitis, rosacea), but no human trials demonstrate that VIP supplementation or VIP-targeting therapies improve skin or hair health. Evidence is mechanistic and observational only.

Thymalin shows plausible immunomodulatory and wound-healing effects in a single small human observational study of frostbite treatment, but efficacy for skin/hair health is not established. The study design and context (acute trauma) do not translate to evidence for cosmetic or general skin/hair applications.

ARA-290 shows promise for wound healing in animal models, particularly in diabetic contexts, but no human trials have been conducted for skin/hair health. Efficacy remains plausible but unproven in humans.

MGF has not been studied in humans for skin and hair health. Evidence is limited to animal models and in-vitro studies showing MGF promotes collagen synthesis, cell proliferation, and tissue repair in connective tissues, but no human efficacy data exists for dermatological or hair applications.

Argireline shows plausible anti-wrinkle and skin-improving effects in animal models and limited human observational studies, but lacks rigorous human RCT evidence. Current data is insufficient to prove efficacy in humans.

Omega-3 supplementation shows mixed and largely inconclusive evidence for skin and hair health. While some studies suggest benefits for atopic dermatitis and wound healing, the most robust evidence (meta-analyses on psoriasis) finds no monotherapy benefit, and one RCT reported increased eczema risk with prenatal omega-3 supplementation.

Vitamin D3 shows mechanistic promise and some positive signals for skin health in human studies, but evidence remains limited and inconsistent. Only 1-2 human RCTs directly tested skin outcomes, with modest improvements in skin hydration and elasticity; most evidence comes from observational studies, mechanistic reviews, or studies where skin was a secondary outcome.

Berberine shows plausible mechanisms for skin and hair health through anti-inflammatory and antioxidant pathways in animal models, but no human clinical trials demonstrate efficacy for skin or hair conditions. All evidence is preclinical.

NMN shows consistent protective effects against photoaging and UV-induced skin damage in animal models with clear mechanistic pathways, but lacks human RCT evidence. Efficacy is plausible but not yet proven in humans for skin/hair goals.

Rhodiola rosea shows plausible but unproven efficacy for skin and hair health. Evidence is limited to animal models, in-vitro studies, and mechanistic research on isolated compounds (salidroside, rosavin); no rigorous human RCTs specifically testing skin or hair outcomes exist.

Maca root shows plausible benefits for skin health through antioxidant and wound-healing mechanisms demonstrated in animal models and in-vitro studies, but lacks human clinical trials to prove efficacy for skin or hair goals.

Elderberry shows plausible mechanisms for skin and hair health through antioxidant and anti-inflammatory properties, but lacks rigorous human clinical trials demonstrating efficacy for these specific goals. Evidence is primarily from in-vitro studies, animal models, and traditional use documentation.

Green tea extract (EGCG) shows plausible benefits for skin and hair health based on multiple animal studies and mechanistic research, but human efficacy evidence is extremely limited—only 1 small RCT and 3 observational studies exist. Efficacy in humans is suggested but not proven.

Spirulina shows promise for skin and hair health through antioxidant, anti-inflammatory, and wound-healing mechanisms demonstrated in animal and in-vitro studies, plus one human RCT for acne; however, efficacy in humans remains largely unproven, with only limited clinical evidence and no robust human trials specifically for hair or general skin health.

Fenugreek shows promise for skin and hair health in animal models and traditional medicine, with evidence of wound healing acceleration and potential 5-alpha reductase inhibition for hair loss. However, no rigorous human RCTs exist to prove clinical efficacy—only observational reports of traditional use and animal studies demonstrating mechanistic plausibility.

Vitamin E shows plausible mechanisms for skin and hair health through antioxidant and anti-inflammatory pathways, but human efficacy evidence is limited to observational studies and small clinical observations with no randomized controlled trials demonstrating clinically meaningful benefits for skin or hair conditions.

Iron supplementation shows plausible benefits for certain hair loss conditions (telogen effluvium) and growth in iron-deficient children, but evidence for skin and hair health is limited to observational studies and case reports with no strong human RCTs demonstrating efficacy. Most human RCTs in this dataset address iron deficiency anemia rather than direct skin/hair outcomes.

Selenium has been extensively studied for skin and hair health, but human evidence shows no clear, proven efficacy for most skin conditions. Multiple RCTs and observational studies in skin cancer prevention, psoriasis, atopic dermatitis, and vitiligo show null or minimal results despite biological plausibility.

Copper supplementation shows consistent effects on fur/hair quality and collagen metabolism in animal models, but human evidence is limited to small pilot studies and observational data in disease states. Efficacy for general skin and hair health in humans remains plausible but not proven.

Chromium has been studied for skin and hair health primarily in the context of PCOS-related hirsutism, where one RCT showed modest reductions in hirsutism when combined with carnitine. However, evidence is very limited and mostly indirect—there are no dedicated studies of chromium for skin or hair health as primary outcomes, and occupational exposure studies document skin damage rather than therapeutic benefit.

Biotin is widely prescribed for hair and skin health, but human evidence of efficacy is limited and inconsistent. Most studies showing positive results are observational or involve biotin as part of multi-ingredient formulations, making it impossible to isolate biotin's specific effect. The strongest concern from the evidence is biotin's interference with laboratory testing, not its benefits.

Fisetin shows promise for skin and hair health through senolytic and anti-inflammatory mechanisms in preclinical studies, but evidence is limited to one small human RCT in wound healing and observational studies in skin disease. Efficacy in humans remains largely unproven.

Spermidine shows promise for hair growth in one double-blind human trial, but efficacy is not yet proven in humans. The bulk of evidence comes from animal studies demonstrating autophagy activation and hair loss reduction in aged mice, with a plausible mechanism but limited human clinical validation.

Urolithin A shows consistent mechanistic promise for skin health in cell and animal models—particularly for photoprotection, wound healing, and collagen support—but lacks robust human clinical trial evidence. Only one human RCT exists, and it did not directly measure skin or hair outcomes.

Sulforaphane shows plausible mechanisms for skin and hair health through NRF2 pathway activation and antioxidant effects, but evidence is primarily mechanistic and pre-clinical. Only one small human RCT (n=18) directly tested skin biomarkers, showing 3.1-3.6-fold increases in NQO1 expression; efficacy for clinical skin or hair outcomes remains unproven in humans.

Astaxanthin shows promise for skin and hair health based on animal and mechanistic studies, but there is NO human clinical evidence demonstrating efficacy for these outcomes. A 2021 meta-analysis identified clinical trials suggesting improvements in skin texture and UV protection, but the analysis itself notes small sample sizes, studies limited to healthy Japanese females, and significant funding conflicts.

Glutathione shows plausible but unproven efficacy for skin and hair health in humans. One small RCT found non-significant trends toward acne improvement, one observational study reported clinical benefit for hair loss, and mechanistic evidence supports antioxidant effects, but no rigorous, adequately powered human trials demonstrate clear clinical efficacy.

Nattokinase has not been proven effective for skin or hair health. The only human RCT on skin showed improved temperature recovery after cold water immersion, but this is a peripheral circulatory response rather than a direct skin or hair health outcome, and results come from a single small study (n=9).

One small human RCT shows shilajit supplementation significantly increases serum pro-c1α1 (a biomarker of type 1 collagen synthesis) over 8 weeks, suggesting a plausible mechanism for skin health. However, efficacy for actual skin or hair outcomes remains unproven—only a circulating biomarker was measured, not clinical skin/hair improvements.

Beta-glucans show plausible mechanisms for skin health through immunomodulation and wound healing in multiple animal and in-vitro studies, but human efficacy for skin and hair remains largely unproven with only observational data and no rigorous clinical trials.

Cordyceps shows promise for skin and hair health based on animal studies and in vitro research demonstrating anti-inflammatory, antioxidant, and wound-healing effects. However, efficacy in humans remains largely unproven, with only one small observational study and primarily cell-based or animal model evidence.

Reishi shows plausible mechanisms for skin and hair health through antioxidant and anti-inflammatory pathways in animal and in-vitro studies, but human efficacy remains largely unproven with only one small human RCT and limited observational data.

Chaga shows promising mechanistic potential for skin and hair health through multiple bioactive compounds (polysaccharides, triterpenes, polyphenols), with consistent in-vitro and animal evidence of anti-aging and hair growth effects. However, no human clinical trials exist, limiting proof of efficacy to laboratory and animal models.

Epicatechin demonstrates plausible mechanisms for skin health through antioxidant and anti-inflammatory pathways in cell and animal studies, but human evidence for skin/hair benefits is minimal and indirect. One small human RCT showed topical epicatechin penetration into stratum corneum, but no clinical skin or hair outcomes were measured.

Pterostilbene shows promise for skin health through multiple mechanistic pathways (antioxidant, anti-inflammatory, collagen induction), but human efficacy evidence is minimal. Only one small human RCT exists; the bulk of evidence is animal studies and in-vitro work.

Grape seed extract shows potential for skin health through antioxidant and collagen-stabilizing mechanisms, but evidence in humans is limited to one small RCT on wound healing and several reviews. Efficacy for general skin and hair health is plausible but not proven.

Stinging nettle shows plausible mechanisms for hair loss (5α-reductase inhibition demonstrated in skin cells) and is traditionally used for hair and skin conditions, but human efficacy for hair growth remains unproven. Evidence is limited to in-vitro studies, animal models, and ethnobotanical reviews with no human RCTs.

Ecdysterone shows consistent wound-healing and skin-protective effects in animal models and limited human/in-vitro studies, with plausible mechanisms involving collagen synthesis and anti-inflammatory pathways. However, efficacy in humans for skin and hair health remains unproven due to absence of rigorous human RCTs.

Tribulus terrestris shows promise for hair pigmentation and melanogenesis in animal and cellular studies, with one small human RCT demonstrating efficacy for acne. However, evidence for skin/hair goals remains limited to preclinical models with no large-scale human trials confirming clinical benefit.

Schisandra chinensis shows promising anti-aging and skin health effects in animal and in-vitro studies, with evidence for photoprotection, antioxidant activity, and wound healing potential. However, only one human study exists (a non-RCT cosmetic formulation test), so efficacy in humans remains unproven.

CLA shows plausible anti-aging and skin health potential based on in vitro collagen synthesis data and one animal study on hair follicle senescence, but human efficacy for skin and hair health remains unproven. Most evidence is mechanistic or in animal/cell models.

Whey protein supplementation has no proven efficacy for skin or hair health. The limited human evidence suggests potential adverse effects (acne exacerbation) rather than benefits for skin.

Astragalus shows promise for skin and hair health through anti-aging, anti-inflammatory, and collagen-promoting mechanisms demonstrated in animal and in-vitro studies, but human clinical evidence remains limited to small trials and observational studies without robust efficacy proof.

Lion's Mane shows promising effects on skin and wound healing in animal models, with one small human RCT demonstrating anti-platelet activity. However, efficacy in humans for skin and hair health is not yet proven.

Bacopa monnieri shows emerging evidence for skin and hair health primarily through wound healing and antioxidant mechanisms demonstrated in animal models. No human clinical trials exist for this compound-goal pairing, limiting definitive efficacy claims.

CDP-Choline has not been directly studied for skin or hair health in humans. Evidence is limited to mechanistic animal studies and one animal wound-healing model showing promise, but no clinical trials demonstrate efficacy for skin or hair goals.

Ginkgo biloba shows emerging promise for skin and hair health based on animal studies and mechanistic research, but robust human clinical evidence remains limited. Most efficacy data comes from animal models or small-scale studies, particularly for vitiligo and hair growth, with only mixed results in human trials.

Panax ginseng shows plausible mechanisms for skin and hair health based on multiple animal and in-vitro studies, but human efficacy evidence is minimal—only 1 RCT and 1 observational study exist among 50 total articles. Efficacy in humans is not yet proven.

Piracetam has been studied for skin and hair health in limited human and animal models, with one small animal study showing enhancement of burn wound healing with topical application. However, no human clinical trials demonstrate efficacy for skin or hair conditions, and the evidence is sparse and primarily mechanistic.

L-Theanine shows promise for skin health through animal studies demonstrating anti-aging and anti-inflammatory effects, but human evidence is limited to a single small RCT combining L-Theanine with multiple other ingredients, making efficacy in humans not yet proven.

Acetyl-L-carnitine shows potential for skin and hair health based on observational biomarker studies and mechanistic reviews, but no human efficacy trials exist. Evidence is limited to metabolic associations in skin disease and one animal ovarian tissue study.

Glycine shows plausible benefits for skin and hair health based on its critical role in collagen synthesis, supported by mechanistic studies and animal research, but human efficacy for skin/hair goals remains unproven with only 2 small human studies lacking direct skin/hair outcome measures.

GABA and GABA-derivative supplements show plausible benefits for skin health through sleep improvement and potential anti-inflammatory mechanisms, but evidence remains limited to one moderate-quality human RCT and mechanistic reviews. Efficacy in humans is not yet proven.

Beta-alanine has shown potential for skin health in a single human case report of aquagenic pruritus and in animal wound-healing models, but efficacy is not proven in humans. Most evidence is mechanistic (via carnosine) or animal-based, with no human RCTs demonstrating skin or hair benefits.

L-Citrulline has not been proven effective for skin and hair health in human studies. While mechanistic research shows L-Citrulline's role in nitric oxide metabolism and animal studies suggest potential benefits for wound healing and skin regeneration, no human RCTs or observational studies directly demonstrate efficacy for skin or hair endpoints.

Taurine shows emerging evidence for skin health benefits in animal models, with one recent 2025 study demonstrating that topical taurine prevents sleep deprivation-induced skin barrier impairment and reduces collagen loss in mice. However, human clinical evidence for skin and hair health is absent from the available literature.

L-carnosine shows plausible antioxidant and skin benefits in animal models, but no human clinical trials exist to prove efficacy for skin or hair health. Current evidence is limited to rat studies and one mechanistic study of a modified carnosine formulation.

L-arginine has been studied for skin and hair health primarily through its role in the nitric oxide pathway and collagen synthesis, but human evidence is limited to small observational studies in acne and wound healing. Animal studies show promise for wound healing and collagen synthesis, but no rigorous human RCTs demonstrate efficacy for hair growth or general skin health.

Leucine supplementation shows consistent effects on connective tissue remodeling and collagen regulation in animal muscle injury models, but there is no direct human evidence demonstrating efficacy for skin or hair health. The mechanistic link to skin/hair goals remains theoretical.

L-lysine shows emerging evidence for skin and herbal support, with one human review reporting efficacy for herpes labialis prophylaxis, but no rigorous human trials exist for general skin/hair health. Evidence is limited to a single review citation and mechanistic in-vitro work on bone cells.

No rigorous human evidence demonstrates that CJC-1295 improves skin, hair, or related outcomes. Available evidence consists only of a netnography of online forum discussions (not clinical data) and a mechanistic study measuring serum protein changes—neither establishes efficacy for skin or hair health.

PT-141 is mentioned only as an FDA-approved melanocortin agonist in a review article about melanocortin receptor genetics and inflammatory diseases. No direct evidence of efficacy for skin or hair health is reported in the available abstracts.

DSIP (Double-Surface Intensive Phototherapy) does not appear in the PubMed literature as a supplement or peptide for skin/hair health. The single identified study uses 'DSIP' as an acronym for a neonatal jaundice treatment protocol (phototherapy), not the compound in question.

Thymosin Alpha-1 has not been studied for skin or hair health outcomes in humans. The only human data comes from a single observational study on vitiligo showing changes in immune markers, but no clinical efficacy endpoints for skin appearance or hair growth were measured.

No evidence demonstrates that MOTS-c improves skin or hair health. The 7 studies identified for this compound-goal pair focus on cardiac function, muscle atrophy, bone metabolism, and intervertebral disc degeneration—none directly address skin or hair outcomes.

SS-31 has not been studied for skin or hair health in humans. One in-vitro study suggests potential benefits for UV-induced skin damage through antioxidant mechanisms, but this is preliminary cell-culture evidence only.

GHRP-2 has not been studied for skin and hair health outcomes. The available abstracts only address growth hormone doping detection and diagnostic testing for GH deficiency—neither of which relate to skin or hair goals.

Melanotan II effectively induces skin pigmentation in humans, but evidence overwhelmingly indicates serious safety risks including melanoma, dysplastic nevi, and systemic toxicity that outweigh any cosmetic benefit. No rigorous efficacy trials exist; all human data come from observational reports of unregulated street use.

Gonadorelin was studied in relation to skin/hair outcomes only as an incidental finding in studies examining hirsutism treatment via androgen suppression, not as a direct therapeutic agent for hair or skin health. No evidence demonstrates gonadorelin itself improves skin or hair conditions.

FOXO4-DRI has not been studied for skin or hair health in any available research. All three PubMed abstracts examine its effects on vascular aging, endothelial senescence, and pulmonary fibrosis—conditions unrelated to the stated health goal.

Vilon (KE dipeptide) shows promise in cell culture for promoting collagen and sirtuin-6 expression in aged skin fibroblasts, but evidence is limited to a single in-vitro study with no human trials demonstrating clinical efficacy for skin or hair health.

Decapeptide-12 shows preliminary evidence for reducing hyperpigmentation based on a single in-vitro skin permeation study, but no human efficacy data exists. The study focused on delivery optimization rather than demonstrating actual therapeutic benefit.

Cortexin is mentioned as a potential treatment option for psychiatric manifestations associated with rosacea in a single 2025 meta-analysis, but no direct evidence of efficacy for skin or hair health is provided. The compound is not studied as a primary intervention in any included studies.

Quercetin has not been studied in human trials for skin and hair health. Available evidence is limited to mechanistic in-vitro findings and animal studies showing potential effects on fibroblasts and connective tissue, but efficacy in humans remains entirely unproven.

Vitamin K2 has not been studied for skin or hair health in any of the available literature. All identified studies focus on bone metabolism, cardiovascular calcification, and obesity-related metabolic changes—none address skin or hair outcomes.

Psyllium husk mucopolysaccharides show theoretical wound-healing properties in animal and in-vitro studies, but there is no clinical evidence of efficacy for skin or hair health in humans.

Glucosamine + Chondroitin has no demonstrated efficacy for skin or hair health. All identified studies focus exclusively on joint and cartilage health; no human or animal evidence supports use for skin or hair goals.

Iodine has no demonstrated efficacy for skin or hair health in humans. The abstracts discuss iodine's role in thyroid function and its use as a treatment for specific dermatological infections and inflammatory conditions (via potassium iodide), but provide no evidence that iodine supplementation improves skin or hair quality, appearance, or health.

TUDCA has not been studied for skin or hair health in humans. All evidence is indirect, derived from animal models of organ fibrosis and stress responses with no direct translation to dermatological or hair outcomes.

Colostrum has not been demonstrated to improve skin or hair health in any human clinical trials. The evidence consists entirely of mechanistic animal studies, in vitro cell culture data, and observational studies focused on immune and allergy outcomes rather than dermatological benefits.

No human evidence exists for apigenin's effects on skin or hair health. The two available studies examine vascular function and skeletal muscle hypertrophy in mice—neither study measured skin or hair outcomes.

No credible evidence supports Mucuna pruriens for skin or hair health. The two available studies address livestock nutrition and erectile dysfunction in diabetic rats—neither directly evaluates effects on human skin or hair.

Echinacea has no proven efficacy for skin or hair health. Available evidence focuses on immunostimulatory properties that may actually harm autoimmune skin patients by triggering or exacerbating disease flares rather than improving skin conditions.

Kava is associated with skin toxicity (ichthyosiform eruption/kanikani) with heavy chronic use, but there is no evidence that kava improves skin or hair health. Historical anecdotal use for skin disorders is mentioned, but no clinical efficacy data supports this application.

Methylene blue has not been demonstrated to improve skin or hair health in any human studies. Available evidence consists of in-vitro cell studies and animal models examining unrelated tissues (nucleus pulposus cells, osteoblasts, diabetic wound healing), with no direct evidence of efficacy for skin or hair goals in humans.

SAMe has not been studied for skin or hair health in any of the available literature. The 17 abstracts discuss SAMe's role in depression, psoriasis inflammation mechanisms, methylation pathways, and various disease states, but none demonstrate efficacy for skin or hair as a primary outcome.

Forskolin has not been proven effective for skin or hair health in humans. The single human RCT found in this set studied vitiligo repigmentation using a gel formulation (VITILSI-) without isolating forskolin's specific contribution, and most evidence comes from mechanistic in-vitro studies or animal models unrelated to skin/hair outcomes.

Betaine HCl has no demonstrated efficacy for skin or hair health in humans. While animal studies and mechanistic research suggest betaine may support collagen synthesis and skin barrier function, there is no human clinical evidence proving it improves skin or hair outcomes.

Phosphatidylserine has not been studied for skin or hair health in any of the available abstracts. All evidence relates to platelet function, coagulation, immune responses, and cellular apoptosis—none of which address dermatological or hair outcomes.

Only theoretical predictions from computational modeling exist for huperzine A and rosacea treatment; no human trials or clinical efficacy data demonstrate that huperzine A actually improves skin health or rosacea outcomes.

No human evidence exists for uridine supplementation improving skin or hair health. The limited studies shown involve unrelated conditions (arthritis, viral infections, pulmonary fibrosis, tendon collagen synthesis), with no research directly addressing dermatological or hair outcomes.

L-Tyrosine's role in skin and hair health is supported only by a single in-vitro review demonstrating increased melanin production in cultured hamster melanoma cells; no human efficacy data exists for this goal.

L-Glutamine has not been studied for skin or hair health in humans. The available evidence consists entirely of mechanistic reviews, dermatitis herpetiformis immunology studies unrelated to glutamine supplementation, and animal studies on fibrosis and renal/cardiac protection—none of which demonstrate efficacy for skin or hair goals.

5-HTP has not been studied for skin or hair health in humans. The available evidence consists of observational metabolomic data showing altered 5-HTP levels in disease states, and animal studies examining unrelated conditions (cardiotoxicity, arthritis, adhesion formation). No efficacy data exists for skin or hair applications.