# Four Compounds, Unequal Evidence > Compare KPV, NAD+, BPC-157 & GHK-Cu — Research Peptide Fundamentals — Research Peptide Fundamentals research peptides compared by compound type, model, mechanism, evidence maturity, measured signal, and key uncertainty. **EVIDENCE MATRIX / SIDE BY SIDE** A model-first comparison of what each compound is, what researchers measured, and where inference stops. ## In plain English These four entries should not be ranked on one “best peptide” scale. They are different kinds of molecules, studied in different systems for different outcomes. KPV has anti-inflammatory findings in cells and animal models but no published human clinical trial. NAD+ is a cellular coenzyme, and the clearest human trials test precursors that raise a blood biomarker. BPC-157 has extensive animal repair research but only tiny human pilot evidence. GHK-Cu has small topical human studies, plus broader cell and gene-expression work. The useful comparison is therefore methodological. Was the experiment done in cells, animals, ex vivo human tissue, or people? Was the endpoint a pathway, a biomarker, a visible tissue change, or a clinical outcome? Was the material the exact compound, a protected formulation, a precursor, or a combination product? Each answer changes how far a finding can travel. The matrix below keeps measured benefit, adverse or cautionary signals, and unresolved questions in separate columns. ## The evidence matrix | Dimension | KPV | NAD+ | BPC-157 | GHK-Cu | | --- | --- | --- | --- | --- | | Molecule | Three-amino-acid alpha-MSH fragment | Cellular dinucleotide coenzyme; not a peptide | Synthetic fifteen-amino-acid peptide | Three-amino-acid copper complex | | Main research area | Inflammation and tissue repair | Redox metabolism and NAD+-consuming enzymes | Angiogenesis, gastric protection, repair | Skin matrix, copper delivery, hair and wound biology | | Strongest evidence layer | Cells and animal models [1][3][6] | Short human precursor trials and reviews [8][9][10][12] | Animal studies; tiny human safety pilot [13][14][16][17] | Small topical or combination human studies, reviews, ex vivo skin [18][20][22] | | Measured signal | Reduced inflammatory activity; model-specific healing | Increased blood NAD+; selected metabolic endpoints | VEGFR2-linked angiogenesis and animal repair | Collagen-related signals, hair-count result in a combination study, skin penetration | | Key caution | No published human trial | Biomarker gains do not prove longevity or prevention | Human efficacy and long-term safety unknown | Topical evidence does not support systemic claims | | Regulatory frame | Unapproved research compound | Form-dependent supplement and compounded-product context | Unapproved investigational compound | Cosmetic topical ingredient context; systemic use unapproved | ## Mechanism is a starting line KPV’s mechanism links PepT1 uptake to reduced NF-kB and MAP-kinase inflammatory signaling [3]. BPC-157’s best-defined pathway links VEGFR2 internalization to Akt and endothelial nitric-oxide signaling [16]. GHK-Cu connects copper handling with fibroblast matrix production and broad gene-expression patterns [19][21]. NAD+ sits beneath many cellular processes as both a redox carrier and a substrate for enzymes such as sirtuins, PARPs, and CD38 [11]. All four mechanisms are biologically meaningful. None, by itself, gives a clinical effect size. A pathway can explain why a result occurred in a model and guide the next experiment. It cannot replace randomized outcomes, pharmacokinetics, adverse-event tracking, or replication. This is why the desk records mechanism in one row and evidence maturity in another. ## What counts as human evidence NAD+ precursor studies provide the most conventional human intervention data in this group: randomized trials measure blood NAD+ and selected functional or metabolic outcomes [9][10][12]. Even there, the 2025 review finds limited clinical efficacy and sparse tissue-level understanding [8]. GHK-Cu has human-facing evidence, but attribution is complicated. A hair trial used a combination product containing GHK [20], while penetration work used excised human skin [22]. BPC-157’s two-person study was a safety pilot without an efficacy endpoint [13]. KPV has no published human clinical trial. “Human evidence” is therefore not one category: randomized intervention, combination trial, ex vivo tissue, and tiny uncontrolled exposure answer different questions. ## Measured benefit, adverse signal, open question For KPV, measured benefits are reduced inflammatory endpoints and faster repair in models; the open question is essentially the full human translation. For NAD+, measured benefits include precursor-driven blood NAD+ increases and a muscle-insulin-sensitivity result, while unchanged body composition and HbA1c in that study limit a broader claim [10]. For BPC-157, animal repair endpoints coexist with theoretical cautions tied to angiogenesis and a clinical sample too small to characterize safety [13][16]. For GHK-Cu, topical and combination-study signals coexist with skin-delivery limits and no basis for systemic anti-aging claims [18][20][22]. No single score captures those tradeoffs honestly. The calm reading is a set of bounded statements: what changed, what did not, how the study was designed, and what still requires a better experiment. ## How to use the comparison The matrix works as a claim-checking tool. A statement about KPV should trace back to a preclinical inflammation or repair model. A claim about NAD+ should distinguish the intact molecule from NMN or NR and identify whether the endpoint is blood concentration or health outcome. A BPC-157 claim should disclose the animal-heavy evidence base. A GHK-Cu claim should name the topical, ex vivo, or combination context. From there, the individual files add study detail: [KPV](/kpv), [NAD+](/nad), [BPC-157](/bpc-157), and [GHK-Cu](/ghk-cu). The [reference ledger](/references) provides the full source trail. --- An independent evidence ledger for four often-overstated compounds—measured findings and uncertainty, never a prescription.