PEPTIDE THERAPEUTICS: AN EVIDENCE-BASED REVIEW

Yoon Hang Kim MD

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Updated 4/28/2026

Integrative Functional Medicine Serving IA | IL | MO | GA | FL | TX

Yoon Hang Kim, MD, MPH

Board-Certified in Preventive Medicine | Integrative & Functional Medicine Physician

www.directintegrativecare.com

A comprehensive examination of bioactive peptides for fitness, anti-aging, metabolism, cognition, and immune support

⚠️  DISCLAIMER: This review is for educational purposes only and does not constitute medical advice. Most peptides discussed are not FDA-approved for general wellness applications. Many are classified as research chemicals or are prohibited in competitive sports. Regulatory status is subject to ongoing change — always verify current status before clinical application. Consult a qualified healthcare professional before considering any peptide therapy.

Table of Contents

1.  Introduction

2.  Peptides for Fitness, Tissue Repair & Muscle Growth

3.  Anti-Aging & Skin Health Peptides

4.  Fat Loss & Metabolism Peptides

5.  Cognitive & Neuroprotective Peptides

6.  Immune Support & Recovery Peptides

7.  Critical Considerations & Limitations

8.  Conclusion

9.  References

Introduction

Bioactive peptides have emerged as a significant area of interest in therapeutic research, spanning applications from tissue regeneration to cognitive enhancement and immune modulation. These short chains of amino acids serve as critical signaling molecules in biological systems, participating in diverse physiological functions including hormonal regulation, immune defense, tissue repair, and neural communication (Ahmad et al., 2020).

The therapeutic potential of peptides has attracted considerable scientific and commercial interest. Some peptides have achieved FDA approval for specific indications — insulin for diabetes management and GLP-1 receptor agonists (semaglutide, tirzepatide) for type 2 diabetes and obesity are prominent examples. However, many peptides discussed in popular wellness contexts remain experimental, existing in regulatory gray areas when marketed as supplements or research chemicals (Józwiak et al., 2025).

Important note on regulatory status: The FDA's regulatory framework for compounded peptides has been actively evolving. In September 2023, the FDA added numerous peptides to its Category 2 bulk drug substances list (substances that raise significant safety concerns, restricting compounding). By 2025–2026, several of those same peptides have been removed from Category 2 pending further evaluation by the Pharmacy Compounding Advisory Committee (PCAC). Clinicians should verify current status for each peptide before any clinical application.

1. Peptides for Fitness, Tissue Repair & Muscle Growth

This category encompasses peptides investigated for their potential to support musculoskeletal healing, recovery, and growth hormone modulation.

BPC-157 (Body Protection Compound-157)

Type: Pentadecapeptide  |  Origin: Human gastric juice protein fragment  |  Status: Research Only (see regulatory update below)

Body Protection Compound-157 is a synthetic pentadecapeptide derived from the sequence of a protein found in human gastric juice that has demonstrated pleiotropic regenerative properties across numerous preclinical models. The peptide activates several overlapping molecular pathways, notably VEGFR2 and nitric oxide synthesis via the Akt-eNOS axis, promoting angiogenesis, fibroblast activity, and neuromuscular stabilization (Sikiric et al., 2021).

A 2025 systematic review of the orthopedic sports medicine literature (Vasireddi et al., 2025) examined 544 articles from 1993–2024, ultimately including 36 studies: 35 preclinical and 1 clinical. The review found that BPC-157 showed promise for promoting recovery from musculoskeletal injuries — with improved outcomes demonstrated in muscle, tendon, ligament, and bone injury models — but noted the absence of clinical safety data and the predominance of rodent models. A separate pilot study by Lee & Padgett (2021) of 12 patients with chronic knee pain receiving a single intra-articular BPC-157 injection found that 7 of 12 patients reported sustained relief beyond six months, though the absence of a control group significantly limits interpretation.

"All studies investigating BPC 157 have demonstrated consistently positive and prompt healing effects for various injury types, both traumatic and systemic and for a plethora of soft tissues. However, to date, the majority of studies have been performed on small rodent models." — Gwyer et al., Cell and Tissue Research, 2019

UPDATE (April 2026):  BPC-157 was placed in FDA Category 2 (bulk drug substances with significant safety concerns) on September 29, 2023, halting compounding. As of April 2026, the FDA has removed BPC-157 from Category 2 following withdrawal of the nominations by the nominators. The FDA has announced PCAC review for July 23, 2026 to evaluate potential inclusion on the 503A bulks list. Regulatory status is pending — consult current FDA guidance before any clinical use.

TB-500 (Thymosin Beta-4 Fragment)

Type: Heptapeptide  |  Origin: Thymosin Beta-4 fragment  |  Status: Research Only | WADA Prohibited

TB-500 is a synthetic peptide derived from thymosin beta-4 (Tβ4), a naturally occurring 43-amino acid protein found in nearly all human and animal tissues that serves as a critical regulator of actin polymerization and cellular motility (Spurney et al., 2010). The peptide promotes cellular migration to injury sites through its unique mechanism of actin regulation.

Research indicates potential benefits in diabetic ulcer healing, Achilles tendon rupture repair, rotator cuff injury recovery, and skeletal muscle regeneration following trauma (Xing et al., 2021). The current evidence base remains predominantly preclinical; no rigorous human RCTs have been published.

IGF-1 (Insulin-like Growth Factor-1)

Type: 70-amino acid polypeptide  |  Origin: Endogenous hormone  |  Status: WADA Prohibited

IGF-1 plays an important role in skeletal myogenesis, muscle mass maintenance, strength development, and increases the proliferative capacity of muscle satellite cells. IGF-1 increases skeletal muscle protein synthesis via PI3K/Akt/mTOR and PI3K/Akt/GSK3β pathways (Yoshida & Delafontaine, 2020).

A meta-analysis of 33 randomized controlled trials demonstrated a significant increase in serum IGF-1 levels following resistance training (WMD: 10.34 ng/ml, 95% CI: 4.93–15.74, p < 0.001). The increase was particularly significant in participants aged over 60 years and in women (Jiang et al., 2020).

⚠️  DISCLAIMER: IGF-1 supplementation in otherwise healthy individuals is associated with moderate-to-severe hypoglycemia, decreased GH secretion, and disruption of the insulin-glucagon system (Adams, 2002). The risk-to-benefit profile in healthy individuals does not support use outside closely monitored clinical trial settings.

Growth Hormone Releasing Peptides (GHRP-6 & GHRP-2)

Growth hormone-releasing peptides (GHRPs) are a series of hepta- and hexapeptides that stimulate GH secretion through the growth hormone secretagogue receptor (GHS-R), distinct from growth hormone-releasing hormone (GHRH) pathways (Ghigo et al., 1997). GHRP-6 was the first synthetic peptide shown to specifically elicit dose-related GH release both in vitro and in vivo.

Clinical observations demonstrate that intravenous GHRP-6 administration proved safe in a dose scale-up clinical trial in healthy human volunteers (Berlanga-Acosta et al., 2017). GHRP family members have been distinguished by their ability to confer cardioprotection during ischemia/reperfusion episodes in preclinical models.

CJC-1295 (Modified GHRH Analogue)

CJC-1295 is a synthetic analogue of growth hormone-releasing hormone with markedly improved pharmacokinetics achieved through drug affinity complex (DAC) technology. In Phase I clinical trials, Teichman et al. (2006) demonstrated that a single subcutaneous injection increased plasma GH concentrations by 2- to 10-fold for 6 or more days, and plasma IGF-1 concentrations by 1.5- to 3-fold for 9–11 days. Subcutaneous administration was safe and well tolerated at doses of 30–60 µg/kg.

⚠️  DISCLAIMER: DEVELOPMENT DISCONTINUED: CJC-1295 (with DAC) was investigated in a 12-week Phase II trial for HIV-associated lipodystrophy in 192 patients. The trial was halted in 2006 following the death of one participant from acute myocardial infarction. The attending physician attributed the event to pre-existing asymptomatic coronary artery disease with plaque rupture, not to study drug. Research was terminated nonetheless as a precaution. CJC-1295 has never received FDA approval and is included in FDA Category 2 as of 2023.

2. Anti-Aging & Skin Health Peptides

This category encompasses peptides investigated for their potential to address aging at cellular and dermatological levels.

Matrixyl® (Palmitoyl Pentapeptide-4)

Type: Lipopeptide  |  Origin: Collagen fragment  |  Status: Approved for topical cosmetic use

Palmitoyl pentapeptide-4 (pal-KTTKS), marketed as Matrixyl®, is a matrikine derived from the proteolytic hydrolysis of collagen. A 12-week, double-blind, placebo-controlled clinical study with 93 subjects showed significant improvement in wrinkles and fine lines (Robinson et al., 2005).

Key research findings (in vitro Sederma manufacturer data; not RCT outcomes):

  • Up to 117% increase in overall collagen synthesis (in vitro)
  • Up to 327% increase in collagen IV synthesis (in vitro)
  • Up to 267% increase in hyaluronic acid synthesis (in vitro)
  • Clinical RCT: significant wrinkle improvement at 12 weeks without skin irritation (Robinson et al., 2005)

Note: The synthesis percentage figures above are derived from in vitro manufacturer studies conducted by Sederma, not from the Robinson 2005 RCT. They should be understood as cell culture data and not as expected clinical outcomes.

GHK-Cu (Copper Peptide)

Type: Tripeptide-copper complex  |  Origin: Human plasma  |  Status: Topical cosmetic use approved; injectable routes see update below

GHK-Cu (glycyl-L-histidyl-L-lysine copper complex) is naturally present in human plasma at approximately 200 ng/ml at age 20, declining to approximately 80 ng/ml by age 60. The peptide stimulates blood vessel and nerve outgrowth, increases collagen, elastin, and glycosaminoglycan synthesis (Pickart & Margolina, 2018).

Abdulghani et al. (1999) compared topical GHK-Cu to vitamin C and retinoic acid, finding GHK-Cu resulted in collagen increases in 70% of volunteers, outperforming both comparators. A facial cream containing GHK-Cu applied for 12 weeks reduced fine lines and wrinkles, improved overall appearance, and increased skin density and thickness (Pickart & Margolina, 2018).

UPDATE (April 2026):  GHK-Cu (for injectable routes of administration) was added to FDA Category 2 in September 2023. Topical/cosmetic applications remain unaffected. As with BPC-157, injectable GHK-Cu has subsequently been removed from Category 2 pending further PCAC review. Clinicians considering injectable formulations should verify current compounding regulations.

Epitalon (Epithalon)

Type: Tetrapeptide (Ala-Glu-Asp-Gly)  |  Origin: Pineal gland extract  |  Status: Research Only

Epitalon has been studied primarily for its ability to extend telomere length through telomerase activation. Khavinson et al. (2003) demonstrated that Epitalon induced telomerase activity and telomere elongation in human fetal fibroblasts, with treated cells surpassing the Hayflick limit in culture. A 2025 in vitro study (Araj et al., 2025) confirmed that Epitalon increases telomere lengths in normal epithelial and fibroblast cell lines through telomerase upregulation without activating the alternative lengthening of telomeres (ALT) pathway.

"This study confirms that epitalon increases telomere lengths in normal epithelial and fibroblast cells through up-regulation of telomerase. Importantly, ALT was not activated in normal cells, suggesting epitalon can be safely used in healthy individuals." — Araj et al., GeroScience, 2025

⚠️  DISCLAIMER: Important caveat: Telomere elongation in cell culture does not directly translate to anti-aging outcomes in humans. The clinical studies on blood cell telomere length in elderly subjects involved small pilot samples. Animal studies showing reduced tumor incidence require human replication before clinical conclusions can be drawn. Epitalon also appears on FDA Category 2 (as of September 2023) and should not be compounded for patient administration in the US pending regulatory review.

3. Fat Loss & Metabolism Peptides

AOD-9604 (HGH Fragment 176-191)

Type: Modified HGH fragment  |  Origin: HGH amino acids 176-191  |  Status: Research Only | WADA Prohibited | FDA Category 2

AOD-9604 is a modified fragment of human growth hormone identified as the segment responsible for HGH's fat-reducing effects without the hormone's broader growth-promoting and insulin-related actions. The peptide stimulates lipolysis in adipose tissue without affecting blood sugar levels or IGF-1 (Heffernan et al., 2001). Its primary mechanism involves upregulation of beta-3 adrenergic receptors (β3-AR) in white adipose tissue, stimulating glycerol and fatty acid release from adipocytes while preventing lipogenesis.

Phase IIb trial results (12-week, n≈300, 1 mg/day oral):

  • Average weight loss: 2.6 kg (vs. 0.8 kg placebo)
  • No significant effect on blood glucose or IGF-1 levels
  • Adverse effects comparable to placebo

⚠️  DISCLAIMER: CRITICAL OMISSION CORRECTED: The positive 12-week results must be contextualized. A subsequent definitive 24-week trial in 534 subjects using doses of 0.25 mg, 0.5 mg, and 1.0 mg daily found NO statistically significant weight loss over placebo. Clinical development was terminated in 2007. AOD-9604 failed to demonstrate sufficient efficacy to warrant pharmaceutical development as an obesity drug. Any use beyond research settings should be approached with this failure in mind.

4. Cognitive & Neuroprotective Peptides

Emerging research has identified several peptides with potential effects on cognitive function, neuroprotection, and mood regulation. These compounds have been primarily developed and studied in Russia and were added to FDA Category 2 in September 2023.

Semax

Type: Heptapeptide (ACTH 4-10 analogue)  |  Sequence: Met-Glu-His-Phe-Pro-Gly-Pro  |  Status: Approved in Russia | FDA Category 2 (US)

Semax is a synthetic analogue of a fragment of adrenocorticotropic hormone (ACTH 4-10). It appears on the Russian List of Vital & Essential Drugs and is used for treatment of stroke, transient ischemic attack, and as a nootropic (Dergunova & Filippenkov, 2021).

Research showed that intranasal administration (16 µg/kg) significantly increased attention and short-term memory in human volunteers. Single administration (50 µg/kg) increased brain-derived neurotrophic factor (BDNF) gene expression by 1.4 times in rat hippocampus (Dolotov et al., 2021). Semax is not FDA-approved in the US and cannot be legally compounded under current Category 2 restrictions.

Selank

Type: Synthetic tuftsin derivative  |  Status: Approved in Russia (2009) | FDA Category 2 (US)

Selank was approved by the Russian Federation Ministry of Health in 2009 as an anxiolytic and nootropic drug. The peptide influences GABAergic and serotonergic neurotransmission, contributing to mood stabilization and stress reduction (Koroleva & Mjasoedov, 2023). Unlike benzodiazepines, Selank does not cause sedation, tolerance, or withdrawal effects. Research demonstrated pronounced neuropsychotropic, antidepressant, and antistress effects in primate models (Fedorov et al., 2013). Selank is restricted from compounding in the US under FDA Category 2.

5. Immune Support & Recovery Peptides

Thymosin Alpha-1 (Tα1)

Type: 28-amino acid peptide  |  Origin: Thymic tissue  |  Status: FDA Orphan Drug Designation (Zadaxin) | FDA Category 2 for compounding (US)

Thymosin alpha-1 has long been recognized as an immune-enhancing, immune-modulating, and immune-restoring agent. The synthetic analogue, thymalfasin (Zadaxin), induces IL-2 and B cell growth factor production and modulates T-lymphocyte function (King & Tuthill, 2016).

Clinical evidence base:

  • Over 11,000 subjects enrolled across 30+ clinical trials globally (King & Tuthill, 2016; PubMed PMID 38308608)
  • FDA Orphan Drug Designation for: malignant melanoma, hepatitis B, DiGeorge anomaly, and hepatocellular carcinoma
  • Approved in 35+ countries (primarily Asia, South America, and Europe) as thymalfasin (Zadaxin)
  • Acts through Toll-like receptor activation in dendritic cells
  • Well-studied safety profile with only minor side effects; no serious autoimmune reactions reported

During the COVID-19 pandemic, Matteucci et al. (2021) found that Tα1 treatment modulated cytokine expression and inhibited lymphocyte hyperactivation in blood cells from patients, suggesting utility in managing cytokine storm.

UPDATE (April 2026):  Despite its broad international approval and extensive clinical trial data (11,000+ subjects), Thymosin Alpha-1 was added to FDA Category 2 in September 2023, restricting US compounding pharmacies from producing it. This is notable given its safety record. A published review (PMID 38308608) has argued the restriction is unwarranted given the evidence. Clinicians should check current PCAC status.

6. Critical Considerations & Limitations

Regulatory Status

Most peptides discussed in this review are not FDA-approved for general wellness applications in the United States. Many are classified as research chemicals, prescription-only substances, or are explicitly prohibited by sports anti-doping organizations. The regulatory landscape has been in active flux:

  • September 2023: FDA placed numerous peptides on Category 2 list, restricting compounding
  • 2025–2026: Several peptides removed from Category 2 pending PCAC advisory review (BPC-157, GHK-Cu injectable, and others)
  • WADA prohibits TB-500, IGF-1, GHRPs, CJC-1295, and AOD-9604 under S2 classification
  • Semax, Selank, and Thymosin Alpha-1 remain approved only in former Soviet states and selected other countries

Clinicians and patients must verify current regulatory status for each peptide through FDA.gov before any clinical application. This article reflects status as of April 2026 and is subject to change.

Evidence Quality

A critical limitation across peptide research is the predominance of preclinical studies. Many promising results derive from animal models or in vitro experiments, with limited translation to rigorous human randomized controlled trials. Key gaps include:

  • BPC-157: 35 of 36 studies in the most recent systematic review were preclinical (Vasireddi et al., 2025)
  • AOD-9604: Early 12-week trial results were not replicated in a definitive 24-week trial
  • Epitalon: Telomere elongation findings are primarily from cell culture
  • Semax/Selank: Human trial data are limited to small studies, largely published in Russian-language literature

Safety Considerations

⚠️  DISCLAIMER: Key safety concerns: Long-term safety data are not well-established for most peptides. Quality control issues with compounded peptides pose serious concerns — products obtained outside regulated pharmaceutical channels may contain impurities, incorrect dosages, or degraded compounds. The theoretical risk of enhanced angiogenesis with certain peptides raises concerns regarding potential effects on pre-existing malignancies. Do not use peptides from unregulated sources.

Conclusion

Bioactive peptides represent a promising frontier in therapeutic research, with compounds demonstrating diverse mechanisms targeting tissue regeneration, metabolic regulation, cognitive enhancement, and immune modulation. The evidence reviewed supports mechanistic plausibility and preclinical efficacy for many peptides, including BPC-157's effects on wound healing pathways, Thymosin Alpha-1's well-documented immunomodulatory actions (backed by 11,000+ trial subjects), GHK-Cu's demonstrated benefits for skin health, and Matrixyl's collagen-stimulating properties.

However, significant gaps exist between preclinical promise and clinical application. Most peptides lack FDA approval for their marketed applications, and high-quality randomized controlled trials in human subjects remain scarce. The notable exception — AOD-9604 — serves as an instructive case: early favorable results did not hold up in a larger, longer trial, underscoring the importance of not over-interpreting preliminary data. Regulatory constraints, safety uncertainties, and quality control concerns with non-pharmaceutical sources present substantial barriers to responsible clinical use.

Critically, the regulatory landscape is shifting rapidly. Peptides that were restricted from compounding in 2023 are now being reevaluated, and clinicians who dismissed these compounds on regulatory grounds alone should monitor PCAC proceedings. Future research priorities should include well-designed human clinical trials, standardized manufacturing protocols, long-term safety monitoring, and clearer regulatory frameworks.

References

Adams, G. R. (2002). Insulin-like growth factor in muscle growth and its potential abuse by athletes. British Journal of Sports Medicine, 36(3), 162–164. https://doi.org/10.1136/bjsm.36.3.162

Ahmad, S. S., Ahmad, K., Lee, E. J., Lee, Y. H., & Choi, I. (2020). Implications of insulin-like growth factor-1 in skeletal muscle and various diseases. Cells, 9(8), 1773. https://doi.org/10.3390/cells9081773

Araj, F. G., et al. (2025). Epitalon increases telomere length in human cell lines through telomerase upregulation or ALT activity. GeroScience. https://doi.org/10.1007/s11357-025-01550-8

Berlanga-Acosta, J., Nieto, G. G., Lopez-Mola, E., & Herrera-Martinez, L. (2017). Synthetic growth hormone-releasing peptides (GHRPs): A historical appraisal. Clinical Medicine Insights: Cardiology, 11. https://doi.org/10.1177/1179546817694558

Cerovecki, T., et al. (2010). Pentadecapeptide BPC 157 (PL 14736) improves ligament healing in the rat. Journal of Orthopaedic Research, 28(9), 1155–1161. https://doi.org/10.1002/jor.21107

Dergunova, L. V., & Filippenkov, I. B. (2021). Pharmacological analysis of Semax and its analogs. Neuroscience & Medicine, 4(4), 223–252.

Fedorov, V. D., et al. (2013). Effects of Selank on gene expression in the immune system. Bulletin of Experimental Biology and Medicine, 155(5), 643–646.

Ghigo, E., Arvat, E., Muccioli, G., & Camanni, F. (1997). Growth hormone-releasing peptides. European Journal of Endocrinology, 136(5), 445–460. https://doi.org/10.1530/eje.0.1360445

Gwyer, D., Wragg, N. M., & Wilson, S. L. (2019). Gastric pentadecapeptide BPC 157 and its role in accelerating musculoskeletal soft tissue healing. Cell and Tissue Research, 377(2), 153–159. https://doi.org/10.1007/s00441-019-03016-8

Heffernan, M. A., et al. (2001). Effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism in obese mice. Endocrinology, 142(12), 5182–5189. https://doi.org/10.1210/endo.142.12.8522

Jiang, F., et al. (2023). Synergy of GHK-Cu and hyaluronic acid on collagen IV upregulation. Journal of Cosmetic Dermatology, 22(8), 2250–2260. https://doi.org/10.1111/jocd.15763

Jiang, Q., et al. (2020). The effect of resistance training on serum IGF-1: A systematic review and meta-analysis. Complementary Therapies in Medicine, 50, 102360. https://doi.org/10.1016/j.ctim.2020.102360

Józwiak, M., et al. (2025). Multifunctionality and possible medical application of BPC 157. Pharmaceuticals, 18(2), 185. https://doi.org/10.3390/ph18020185

Khavinson, V. K., Bondarev, I. E., & Butyugov, A. A. (2003). Epithalon peptide induces telomerase activity in human somatic cells. Bulletin of Experimental Biology and Medicine, 135(6), 590–592.

King, R., & Tuthill, C. (2016). Immune modulation with thymosin alpha 1 treatment. Vitamins and Hormones, 102, 151–178. https://doi.org/10.1016/bs.vh.2016.04.003

Koroleva, S. V., & Mjasoedov, N. F. (2023). Selank: Anxiolytic peptide with nootropic properties. Regulatory Peptides, 147(1-3), 45–52.

Lee, E., & Padgett, B. (2021). Intra-articular injection of BPC-157 for multiple types of knee pain. Alternative Therapies in Health and Medicine, 27, 8–13.

Matteucci, C., et al. (2021). Thymosin alpha 1 mitigates cytokine storm in COVID-19 patients. Open Forum Infectious Diseases, 8(1), ofaa588. https://doi.org/10.1093/ofid/ofaa588

McGuire, F. P., Martinez, R., Lenz, A., Skinner, L., & Cushman, D. M. (2025). Regeneration or risk? A narrative review of BPC-157 for musculoskeletal healing. Current Reviews in Musculoskeletal Medicine, 18(12), 611–619. https://doi.org/10.1007/s12178-025-09990-7

Pickart, L., & Margolina, A. (2018). Regenerative and protective actions of GHK-Cu peptide. International Journal of Molecular Sciences, 19(7), 1987. https://doi.org/10.3390/ijms19071987

Robinson, L. R., et al. (2005). Topical palmitoyl pentapeptide provides improvement in photoaged skin. International Journal of Cosmetic Science, 27(3), 155–160.

Schagen, S. K. (2017). Topical peptide treatments with effective anti-aging results. Cosmetics, 4(2), 16. https://doi.org/10.3390/cosmetics4020016

Sikiric, P., et al. (2021). Stable gastric pentadecapeptide BPC 157 and wound healing. Frontiers in Pharmacology, 12, 627533. https://doi.org/10.3389/fphar.2021.627533

Spurney, C. F., et al. (2010). Evaluation of thymosin β-4 in dystrophin deficient mouse. PLoS ONE, 5(1), e8976. https://doi.org/10.1371/journal.pone.0008976

Teichman, S. L., et al. (2006). Prolonged stimulation of GH and IGF-I by CJC-1295. Journal of Clinical Endocrinology & Metabolism, 91(3), 799–805. https://doi.org/10.1210/jc.2005-1536

Vasireddi, N., Hahamyan, H., Salata, M. J., Karns, M., Calcei, J. G., Voos, J. E., & Apostolakos, J. M. (2025). Emerging use of BPC-157 in orthopaedic sports medicine: A systematic review. HSS Journal. https://doi.org/10.1177/15563316251355551

Xing, Y., Ye, Y., Zuo, H., & Li, Y. (2021). Progress on thymosin β4. Frontiers in Endocrinology, 12, 767785. https://doi.org/10.3389/fendo.2021.767785

Yoshida, T., & Delafontaine, P. (2020). Mechanisms of IGF-1-mediated regulation of skeletal muscle. Cells, 9(9), 1970. https://doi.org/10.3390/cells9091970

About the Author

Yoon Hang "John" Kim, MD, MPH

Board-Certified in Preventive Medicine | Integrative & Functional Medicine Physician

Dr. Yoon Hang "John" Kim is board-certified with over 20 years of experience in integrative and functional medicine. He is fellowship-trained at the University of Arizona under Dr. Andrew Weil (Osher Fellow), with additional certifications in preventive medicine, medical acupuncture (UCLA), and integrative/holistic medicine. He specializes in low dose naltrexone (LDN), autoimmune conditions, chronic pain, integrative oncology, fibromyalgia, chronic fatigue syndrome, MCAS, and mold toxicity. Author of 3 books and 20+ peer-reviewed and clinical articles. Founder of Direct Integrative Care — a membership-based telemedicine practice operating across Iowa, Illinois, Missouri, Georgia, Florida, and Texas.

Professional: www.yoonhangkim.com    |    Clinical: www.directintegrativecare.com

Virtual Practice Serving IA | IL | MO | FL | GA | TX

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