Men's Skin Clock Report

A Free Report From Burton Kimball

The Men’s Skin Clock

What 30 years of peer-reviewed peptide research reveals about aging male skin — and why every day you wait is written on your face.

A note before you read. This is an educational report about the scientific literature surrounding five peptides that appear in Burton Kimball Age Defense Men’s Multi-Peptide Face Cream. The research cited in this report was conducted on the ingredients themselves, in laboratory, ex vivo, and clinical settings, and is reported here as it appears in the peer-reviewed literature.

Burton Kimball Age Defense is a cosmetic product. Like all cosmetics, it is intended to beautify and improve the appearance of the skin. Nothing in this report should be read as a claim that this product diagnoses, treats, cures, or prevents any disease, or that it alters the structure or function of the human body. What the research shows about the ingredients is a separate question from what a finished cosmetic product does, and we are careful throughout this report to keep that distinction clean.

With that said — we don’t think the science needs to be watered down. Men deserve to know what real laboratories, using real instruments, have actually measured. So that’s what this report is about.

Part One

The Clock No One Tells Men About

There is a number in the dermatology literature that almost no man hears until it’s too late.

Starting in the mid-twenties, skin collagen declines at approximately 1% per year, every year, for the rest of your life. This figure comes from a landmark study by Shuster and colleagues, who measured forearm skin collagen density in 148 men and women aged 15 to 93. The rate of loss was found to be essentially the same in both sexes. It is linear. It does not pause. It does not reverse on its own.

Do the math on your own face:

If you are 35, you have lost roughly 10% of the collagen you had at 25.
If you are 45, you have lost roughly 20%.
If you are 55, you have lost roughly 30%.
If you are 65, you have lost roughly 40%.

And this is only the baseline decline — the number before you factor in sun exposure, smoking, alcohol, poor sleep, chronic stress, and the accumulated damage of decades of shaving, weather, and neglect.

Published research indicates that for men specifically, epidermal thickness declines at approximately 7.2% per decade, which is actually steeper than the 5.7% per decade documented in women. Men start with thicker, more collagen-dense skin than women do — but once the decline begins, men’s skin thins faster. The result is that the visible signs of aging in men, when they finally arrive, tend to arrive all at once: deeper lines, coarser texture, looser jawlines, and the gaunt, hollow look that men recognize in the mirror the morning they suddenly look like their father.

There is another concept in the recent literature that every man over 30 should understand. It is called inflammaging.

Inflammaging refers to the persistent, low-grade, subclinical inflammatory state that accumulates in skin and other tissues with age. It is driven by senescent cells, UV-damaged keratinocytes, glycation end-products, and other sources of chronic cellular stress. The significance of inflammaging is that it accelerates collagen breakdown. It is not a passive background process. It is actively degrading the protein scaffolding of your face every day, silently, whether you feel anything or not.

And here is the part that most men get wrong:

You cannot feel any of this happening.

You do not feel your collagen dropping 1% a year. You do not feel your epidermis thinning 7.2% a decade. You do not feel inflammaging chewing through your dermal matrix. By the time you see the result in the mirror, the underlying structural change has already been in progress, compounding, for 10, 20, or 30 years.

This is the single most important thing to understand about men’s skin aging. The visible wrinkle, the sag, the crease, the hollow — these are not the damage. These are the symptom of damage that has already occurred and has been occurring for decades.

Which brings us to the reason for this report.

Part Two

Why Every Day You Wait Is Written on Your Face

Most men, in our experience, fall into one of three buckets.

The 30-something man looks in the mirror, sees a few fine lines around the eyes, and tells himself there’s plenty of time. “I’ll deal with it in a few years.” He doesn’t realize that the dermal fibroblasts responsible for manufacturing new collagen in his face are already producing less than they did a decade ago. He doesn’t realize that the years between 30 and 40 are the years with the highest return on investment for skincare — because the raw material is still responsive.

The 40-something man looks in the mirror and sees that the lines have deepened. He notices the skin under his eyes is beginning to crepe. He tells himself he “should probably start using something” — and does nothing. Meanwhile, published research has documented that by the 40s, the skin is showing measurable reductions in collagen I, loss of dermal density, and the first clinical signs of elastic fiber fragmentation.

The 50-something (or 60-something) man looks in the mirror and sees a face that surprises him. The jaw is softer. The texture is rougher. The hollows under the eyes have set in. And his instinct is the most dangerous instinct of all: “It’s too late.”

It is not too late.

The peer-reviewed research on the specific peptides we are about to discuss does not stop being interesting at 50, or 60, or 70. In fact, many of the published clinical studies on these ingredients have been conducted specifically in older skin, because older skin is where the underlying mechanisms — reduced fibroblast activity, elevated MMP expression, chronic low-grade inflammation — are most pronounced and most measurable. The starting point is worse, yes. But the research signal in older skin is often clearer, not weaker.

Here is the principle we want every man reading this to internalize:

The worst day to start taking care of your skin was ten years ago.
The second worst day is tomorrow.

If you are 32, the research is clear that the dermal environment you are working with today will not exist in this form in five years. Every month you wait is a month of 1%-per-year decline compounding against you.

If you are 52, the research is equally clear that the collagen-stimulating and anti-inflammatory signaling pathways documented in the peptide literature do not require young skin to respond. In many of the studies we are about to discuss, the subjects were women and men well into their 50s, 60s, and beyond.

The only wrong move is to keep waiting.

Part Three

The Five Peptides — And What the Literature Actually Shows

This is the section we’ve been building toward. We want to be very precise in how we discuss this material.

What follows is a summary of what has been reported in the peer-reviewed scientific literature about five specific peptides — the same five peptides that appear in Burton Kimball Age Defense. We are going to describe what researchers have measured, in their own terminology, in laboratory and clinical settings. This is not a product claim. This is a literature review.

The five peptides are:

Tripeptide-1
Palmitoyl Tetrapeptide-7
Palmitoyl Tripeptide-5
Hexapeptide-9
Palmitoyl Pentapeptide-4

Most peptide creams on the market contain one peptide. Some contain two, or three, or four. Burton Kimball was formulated with all five because the published literature shows that these peptides work through different and complementary mechanisms. One stimulates collagen through one pathway. Another stimulates it through a second, independent pathway. A third modulates inflammation. A fourth interacts with the basement membrane. A fifth addresses the extracellular matrix through yet another mechanism. A man over 30 is not dealing with one problem — he is dealing with a stack of overlapping problems, each requiring a different signaling intervention.

Now to the research.

Peptide 1 of 5

Tripeptide-1 (Glycyl-Histidyl-Lysine, or “GHK”)

Tripeptide-1 is the peptide sequence Glycine–Histidine–Lysine, more commonly known in the research literature as GHK. It was originally isolated from human plasma in 1973 by Dr. Loren Pickart, who discovered that older human liver tissue, when exposed to GHK, began producing proteins more characteristic of younger tissue.

Since then, GHK has accumulated one of the largest and most-cited peer-reviewed bodies of evidence of any cosmetic peptide.

What the published literature reports about GHK:

Declining endogenous levels with age. GHK occurs naturally in human plasma, saliva, and urine. Published research indicates that standard levels drop by more than half by age 60. In other words, your body makes less of this peptide as you get older — which is itself part of the aging process.
Collagen and extracellular matrix activity. Multiple studies, including the work of Maquart and colleagues, have documented that GHK-copper complex at very low concentrations stimulates both synthesis and remodeling of collagen and glycosaminoglycans in cultured human fibroblasts. The researchers found modulation of both matrix metalloproteinases (MMPs, which break down collagen) and their inhibitors (TIMPs, which protect collagen).
Clinical facial studies. A series of facial studies published in the peer-reviewed literature have reported improvements in the appearance of wrinkles, skin density, and skin thickness following topical application of GHK-containing formulations. In one frequently cited study, 41 women with mild to advanced photodamage applied a GHK-containing eye cream for three months and demonstrated reductions in the appearance of lines and wrinkles compared with both placebo and a vitamin K cream.
Wound-remodeling and elastin research. Research has documented that GHK, particularly in its copper-bound form, inhibits elastase activity (the enzyme that degrades elastin) and has been associated with tissue repair in multiple in vivo models.
Review literature. A 2023 review in Frontiers in Pharmacology describes GHK as a carrier peptide with documented effects on skin rejuvenation, and notes its widespread use in cosmetic products for this reason.

In plain English: Tripeptide-1 is one of the best-studied anti-aging peptides in the published literature, and the research reports measurable effects on the specific biological processes — collagen turnover, elastase inhibition, and fibroblast activity — that decline with age in men’s skin.

Peptide 2 of 5

Palmitoyl Tetrapeptide-7

Palmitoyl Tetrapeptide-7 (sequence Pal-Gly-Gln-Pro-Arg) is a synthetic peptide derived from a fragment of immunoglobulin G. It is the less-famous half of a well-known cosmetic ingredient combination called Matrixyl 3000, but it has its own independent published evidence base going back more than two decades.

What the published literature reports:

Interleukin-6 (IL-6) suppression. This is the peptide’s headline finding. Multiple published studies have documented that Palmitoyl Tetrapeptide-7 reduces the secretion of interleukin-6, a pro-inflammatory cytokine, in keratinocytes. IL-6 is one of the principal signaling molecules driving the inflammaging process we discussed earlier. In in vitro experiments, researchers have reported a dose-dependent reduction in cellular interleukin production.
UVB-associated inflammatory response. Published research indicates that Palmitoyl Tetrapeptide-7 inhibits the inflammatory response of skin cells following UVB radiation exposure. UVB is one of the primary drivers of photoaging in men who have spent decades working outdoors, golfing, driving with the window down, or otherwise accumulating sun exposure.
Extracellular matrix support. Research published in connection with this peptide has reported dose-response relationships with collagen I, fibronectin, and hyaluronic acid synthesis in laboratory models. It has also been reported to stimulate laminin IV and VII expression, components of the dermal-epidermal junction.
Recent research. A 2024 publication in Skin Research and Technology by Yang and colleagues evaluated a multi-component topical eye cream containing Palmitoyl Tetrapeptide-7 and reported significant improvements on measured wrinkle parameters in the periorbital area.

In plain English: Palmitoyl Tetrapeptide-7 is the peptide that specifically targets the inflammation-driven collagen breakdown that is silently aging most men over 30. It doesn’t primarily build new collagen — its role is to stop the slow burn that is taking it away.

Peptide 3 of 5

Palmitoyl Tripeptide-5

Palmitoyl Tripeptide-5 (sequence Pal-Lys-Val-Lys), known commercially as Syn-Coll, is a synthetic lipopeptide engineered to mimic the activity of thrombospondin-1 (TSP-1), a naturally occurring extracellular matrix protein that activates transforming growth factor-beta (TGF-β).

TGF-β is one of the most potent endogenous regulators of collagen biosynthesis in human dermal fibroblasts.

What the published literature reports:

TGF-β activation pathway. Published research indicates that Palmitoyl Tripeptide-5 mimics the specific sequence in TSP-1 (Lys-Arg-Phe-Lys) responsible for activating latent TGF-β. Once TGF-β is released from its latent form, it binds receptors on fibroblasts and triggers the Smad signaling cascade that upregulates gene transcription for collagen I, collagen III, and fibronectin. This is a well-characterized pathway with decades of published biochemistry behind it.
Comparative collagen stimulation. In vitro studies have reported that Palmitoyl Tripeptide-5 produces collagen-stimulating activity comparable to or greater than TGF-β itself in cultured fibroblasts. One supplier-published report documents 119% collagen I stimulation at 3 ppm.
MMP inhibition. Published research also reports that Palmitoyl Tripeptide-5 may inhibit matrix metalloproteinases MMP-1 and MMP-3, the enzymes responsible for breaking down existing collagen. This is a two-sided activity — stimulating new collagen while also slowing the breakdown of existing collagen.
Clinical study data. A clinical study with 60 volunteers, reported in the ingredient technical literature, documented significant reductions in the appearance of wrinkles after 84 days of twice-daily application.

In plain English: If Tripeptide-1 is the all-rounder and Palmitoyl Tetrapeptide-7 is the anti-inflammatory, Palmitoyl Tripeptide-5 is the collagen-focused specialist — hitting the single biggest signaling pathway the body uses to rebuild its own structural proteins.

Peptide 4 of 5

Hexapeptide-9

Hexapeptide-9 (sequence Gly-Pro-Gln-Gly-Pro-Gln) is a synthetic six-amino-acid peptide that mimics a fragment of collagen IV and XVII — key collagens of the basement membrane, which is the structural interface between the epidermis and the dermis.

This is the peptide that targets a part of the skin almost nobody thinks about: the foundation.

What the published literature reports:

Basement membrane collagens. Published research characterizes Hexapeptide-9 as a collagen peptide that promotes dermal collagen synthesis, supports the dermal-epidermal junction, and contributes to epidermal differentiation.
Supplier-published efficacy data. Manufacturer-published clinical research on Hexapeptide-9 has reported increases in overall collagen production of up to 117%, with collagen IV (the basement membrane collagen) reported to increase by up to 357%, and hyaluronic acid production reported to increase by up to 267%, at tested concentrations in laboratory models. Pictorial comparative analyses reported reductions in the appearance of deep wrinkled surface area averaging 68%.
Head-to-head clinical trial vs. retinol. Here is one of the most striking pieces of recent research. A 2025 randomized, double-blinded, active- and vehicle-controlled clinical trial, published in the peer-reviewed literature, compared a cyclized form of Hexapeptide-9 against retinol — the long-standing gold-standard cosmetic anti-aging ingredient. The published results reported that the hexapeptide-9 formulation significantly decreased the number, area, and roughness of crow’s feet and forehead wrinkles, and that for several of these measures it demonstrated a significantly larger effect than retinol. The study concluded that hexapeptide-9, in this form, was more potent than retinol in improving skin-aging-related measures, particularly with long-term use.
Safety profile. The published literature consistently reports that Hexapeptide-9 is well-tolerated, without the irritation profile comparable to retinoids.

In plain English: Hexapeptide-9 is, by the published clinical evidence, one of the most promising anti-aging peptides in the modern cosmetic science literature — and it is gentle enough that it does not produce the redness, flaking, or sensitivity that many men abandon retinol over.

Peptide 5 of 5

Palmitoyl Pentapeptide-4

Palmitoyl Pentapeptide-4 (sequence Pal-Lys-Thr-Thr-Lys-Ser, or Pal-KTTKS), known commercially as Matrixyl, is one of the most rigorously studied peptides in all of cosmetic science. It was established as a topical anti-aging active around the year 2000 and has been the subject of continuous research ever since.

What the published literature reports:

Procollagen I fragment origin. The KTTKS sequence is derived from the C-terminal of human type I procollagen. Published biochemistry describes this sequence as a signaling fragment that fibroblasts interpret as feedback about collagen breakdown — essentially, the body’s own internal “rebuild” signal.
Collagen and extracellular matrix synthesis. Published research reports that Palmitoyl Pentapeptide-4 stimulates collagen synthesis and other dermal matrix components in vitro and in vivo. Additional studies have documented inhibition of excess dermal glycosaminoglycan production associated with aged skin, and induction of epidermal thickening.
Multiple chronic human studies. Multiple peer-reviewed human studies of topical Pal-KTTKS have reported improvements in the appearance of facial wrinkles, without the irritation, redness, or barrier damage associated with retinol-based technologies. In self-assessments reported in the published literature, subjects reported significant improvements in facial wrinkles and smaller but statistically significant improvements in the appearance of age spots, dark circles, and firmness.
Randomized double-blind trial. A published double-blind, randomized controlled trial compared Palmitoyl Pentapeptide-4 cream against placebo for periorbital (crow’s feet) wrinkles over eight weeks in subjects aged 26–55. Improvements were measured by Corneometer, Tewameter, Cutometer, digital photography, and the Crow’s Feet Grading Scale.
Comparable to retinol without the irritation. This is the practical bottom line of the published Matrixyl literature. Multiple sources in the peer-reviewed and industry literature have characterized Palmitoyl Pentapeptide-4 as producing anti-aging measurement outcomes comparable to retinoic acid, without the irritation that leads so many users to discontinue retinol within weeks.

In plain English: Palmitoyl Pentapeptide-4 is the workhorse. Twenty-plus years of research, dozens of studies, clinical outcomes, and one of the most consistent safety records in the literature.

Part Four

Why Five Peptides, Not One

Here is a question we get often:

“If one peptide works, why do I need five?”

The answer is in the literature itself. Each of the five peptides operates on a different biological pathway:

Tripeptide-1 (GHK) — modulates fibroblast activity, MMP/TIMP balance, elastase, and the copper-dependent components of collagen and elastin metabolism.
Palmitoyl Tetrapeptide-7 — targets the IL-6 inflammatory cascade and the UVB-associated inflammatory response.
Palmitoyl Tripeptide-5 — activates the TGF-β / Smad collagen synthesis cascade and inhibits MMP-1 and MMP-3.
Hexapeptide-9 — supports basement membrane collagens (collagen IV and XVII) and hyaluronic acid synthesis.
Palmitoyl Pentapeptide-4 — signals through the procollagen-I feedback pathway and addresses dermal glycosaminoglycan balance.

These are five different mechanisms. Targeting only one of them is like hiring a contractor to work on only one wall of a five-wall renovation. The published literature — particularly research on combination formulations — has consistently pointed toward synergistic effects when multiple peptide pathways are addressed together.

This is why Burton Kimball Age Defense was formulated with all five.

Part Five

The Men’s Skin Question No One Asks

Here is something the cosmetic industry rarely talks about: almost all of the peptide research was conducted on women.

This matters, because men’s skin is structurally different. Men start with thicker dermis. Men have higher collagen density early in life. Men have more active sebaceous glands. And — as we noted earlier — men’s epidermal thinning accelerates at a steeper per-decade rate than women’s once the decline begins.

Translation: the mechanisms the research documents are, if anything, likely to be more relevant to men over 30 than to the women the studies were conducted on, because men have further to fall once the biological clock turns over. And yet the industry has spent thirty years marketing peptide creams at women while quietly watching men age into mirrors they don’t recognize.

We think that’s backwards. Men care how they look. Men care how they are perceived at work, in relationships, and in the simple morning ritual of looking at their own face and feeling like the person looking back is still them. We just haven’t been given a product that speaks to us, with the research actually laid out, without being told we should be using our wife’s lavender-scented moisturizer.

Burton Kimball Age Defense is our answer to that.

Part Six

What to Do Next

If you’ve read this far, you already know more about the peer-reviewed peptide literature than 99% of men your age.

Here is our simple recommendation:

Don’t wait. The 1%-per-year collagen decline doesn’t take weekends off. Every day you delay is a day of compounding loss that cannot be undone.
Don’t overcomplicate. You do not need a 12-step regimen. A single, well-formulated, multi-peptide cream applied consistently twice a day, morning and night, after washing your face, is a meaningful intervention.
Be consistent. The published clinical studies that measured meaningful changes in the appearance of wrinkles generally did so over 28 days, 56 days, 84 days, or longer. This is not an overnight product category. Nothing real is. But consistency for 60 to 90 days is what the research suggests produces visible results.
Protect what you have. Daily sunscreen is non-negotiable. UV is the single largest external accelerator of everything we’ve discussed in this report.

Try Burton Kimball

Age Defense Men's Multi-Peptide Face Cream

All five peptides. One jar. Built for men who've read the research and aren't willing to keep waiting.

Shop Burton Kimball

Appendix

The Full Ingredient List

Burton Kimball Age Defense Men’s Multi-Peptide Face Cream contains:

Aqua, Helianthus Annuus (Sunflower) Seed Oil, Caprylic/Capric Triglyceride, Aloe Barbadensis Leaf Juice, Glyceryl Stearate Citrate, Cetyl Alcohol, Glycerin, Stearic Acid, Isopropyl Myristate, Persea Gratissima (Avocado) Oil, Simmondsia Chinensis (Jojoba) Seed Oil, Panthenol, Proline, Sodium Hyaluronate, PCA, Tripeptide-1, Palmitoyl Tetrapeptide-7, Palmitoyl Tripeptide-5, Hexapeptide-9, Sodium PCA, Camellia Sinensis Leaf Extract, Isoleucine, Histidine, Centella Asiatica Extract, Threonine, Glycine, Sodium Lactate, Butyrospermum Parkii (Shea) Butter, Phenylalanine, Arginine, Aspartic Acid, Alanine, Serine, Valine, Palmitoyl Pentapeptide-4, Tocopherol, Carbomer, Sodium Benzoate, Phenoxyethanol, Ethylhexylglycerin, Potassium Sorbate, Polysorbate 20, Parfum (0.25%).

Selected References

For the Reader Who Wants to Go Deeper

Shuster S, Black MM, McVitie E. The influence of age and sex on skin thickness, skin collagen and density. British Journal of Dermatology.

Pickart L. The human tri-peptide GHK and tissue remodeling. Journal of Biomaterials Science, Polymer Edition, 2008; 19(8):969–988.

Pickart L, Margolina A. Regenerative and protective actions of the GHK-Cu peptide. Various peer-reviewed publications, 2015 and following.

Maquart F, Bellon G, Chaqour B, Wegrowski J, et al. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex GHK-Cu in rat experimental wounds.

Varga J, Rosenbloom J, Jimenez SA. Transforming growth factor beta (TGF-beta) causes a persistent increase in steady-state amounts of type I and type III collagen and fibronectin mRNAs in normal human dermal fibroblasts. Biochemical Journal, 1987; 247:597–604.

Murphy-Ullrich JE, Poczatek M. Activation of latent TGF-beta by thrombospondin-1: mechanisms and physiology. Cytokine & Growth Factor Reviews, 2000; 11:59–69.

Yang F, Zhang X, Wang H, Guo M, et al. Comprehensive evaluation of the efficacy and safety of a new multi-component anti-aging topical eye cream. Skin Research and Technology, 2024.

Novel Cyclized Hexapeptide-9 Outperforms Retinol Against Skin Aging: A Randomized, Double-Blinded, Active- and Vehicle-Controlled Clinical Trial. PubMed ID 40586182, 2025.

Double-blind, Randomized Trial on the Effectiveness of Acetylhexapeptide-3 Cream and Palmitoyl Pentapeptide-4 Cream for Crow’s Feet. PMC10005804.

Jeong S, et al. Topical Peptide Treatments with Effective Anti-Aging Results. Cosmetics, MDPI, 2017; 4(2):16.

Exploring the Role of Tripeptides in Wound Healing and Skin Regeneration: A Comprehensive Review. International Journal of Medical Sciences.

Peptides: Emerging Candidates for the Prevention and Treatment of Skin Senescence: A Review. PMC11762834.

Biochemical, structural and physical changes in aging human skin, and their relationship to mechanical function. PMC10316705.

Skin Aging and Type I Collagen: A Systematic Review of Interventions with Potential Collagen-Related Effects. Cosmetics, MDPI, 2025.

U.S. Food and Drug Administration. Cosmetics Labeling Claims.

Disclaimers. Burton Kimball Age Defense Men’s Multi-Peptide Face Cream is a cosmetic product intended to beautify and improve the appearance of the skin. It is not intended to diagnose, treat, cure, or prevent any disease.

The research summarized in this report was conducted on the individual ingredients, typically in laboratory, ex vivo, and clinical research settings. Results from ingredient-level research do not constitute claims about the performance of any finished product. Individual results will vary.

Patch test any new product before regular use. Discontinue use if irritation occurs. Avoid contact with eyes. Keep out of reach of children. For external use only.