Peptides: Small Molecules with Specific Jobs — in Skin and Hair

In recent years, the word peptides appears almost everywhere in the world of skincare. In serums, in creams, in hair products, and even in nutritional supplements. We are promised firmer skin, fewer wrinkles, stronger hair, and sometimes even renewed hair growth.

But what are peptides, actually? How do they act in the body? Can they really encourage collagen production and improve the condition of the hair? And is every product that contains peptides able to provide the results promised to us?

To understand their benefits, we first need to understand the role they play in our body.

What are peptides?

Peptides are short chains of amino acids, which are the building blocks of the proteins in the body.

When amino acids join one another, they create chains of different lengths. Short chains are usually called peptides, and longer, more complex chains may create proteins.

Our body produces peptides naturally. Some of them take part in communication between cells, others are involved in hormonal processes, in the immune response, and in regulating various biological activities.

The skin and the hair follicles are also influenced by these signaling systems.

In the cosmetics industry, certain peptides are used with the aim of influencing processes related to the appearance of the skin, its protective barrier, and the function of the hair follicles.

But it is important to understand that not all peptides act in the same way.

How do peptides affect the skin?

Our skin is built from a complex system of cells, proteins, lipids, and molecules that support its structure and function.

In the dermis layer are found, among other things, collagen and elastin, two proteins with a central role in the structure of the skin and its elasticity.

Over the years, changes occur in the production and breakdown of these proteins. Exposure to UV radiation, smoking, and natural aging processes contribute to changes in the appearance of the skin.

Certain peptides are studied for their ability to influence the activity of cells involved in maintaining the tissue.

Some of them act as signaling molecules, meaning they may pass messages to the cells related to repair processes and protein production.

Others are intended to influence processes related to the movement of superficial muscles or to the transport of minerals important for enzyme activity.

However, activity observed in a laboratory does not guarantee that the same peptide will act with the same strength when it is applied to the skin.

The common types of peptides in skincare products

1. Signal peptides

These are peptides studied for their ability to influence processes related to protein production in the skin's extracellular matrix.

One of the well-known ones is Palmitoyl Pentapeptide-4, also known by the name Matrixyl.

Additional peptides, such as Palmitoyl Tripeptide-1 and Palmitoyl Tetrapeptide-7, appear in formulas intended to improve the appearance of mature skin.

Certain studies point to an improvement in fine lines and in skin texture, but the clinical evidence is still limited and depends on the product's composition.

2. Carrier peptides

One of the well-known ones in the group is GHK-Cu, a peptide bound to copper.

Copper takes part in various enzymatic processes in the body, including processes related to connective tissue.

Copper peptides are studied in the context of tissue repair, fibroblast activity, and changes in the appearance of the skin.

Despite the scientific interest, there are still not enough large clinical studies to determine the degree of effectiveness of every preparation containing copper peptides.

3. Peptides that affect neural signaling pathways

In this group is found, for example, Acetyl Hexapeptide-8, also known by the name Argireline.

It is sometimes marketed as an ingredient that helps reduce the appearance of expression lines.

But it is important to clarify: cosmetic peptides do not act like an injection of botulinum toxin, and there is no proof that they are able to reach the same effect on the muscles.

4. Enzyme-inhibiting peptides

Some peptides are studied for their ability to influence enzymes involved in the breakdown of proteins or in other processes in the skin.

Here too, the effect depends on the structure of the peptide, its concentration, and its ability to reach the area where it is supposed to act.

Do peptides really encourage collagen production?

This is one of the most common promises in the field of cosmetics.

There is a biological basis for the idea that certain peptides may influence processes related to collagen production. Laboratory studies and a number of small clinical studies point to a potential for improving the appearance of the skin.

But there is a difference between encouraging cellular activity under laboratory conditions and proof of increased collagen production in human skin following the use of a cream.

In addition, collagen is found mainly in the dermis, while skincare products are applied to the outer layer of the skin.

For a peptide to influence deeper cells, it must penetrate through the skin barrier or act through another suitable mechanism.

Not every peptide is able to do that.

Therefore, the quality of the formula, the stability of the substance, the concentration, and the way it is delivered are no less important than the name that appears on the packaging.

Peptides and hair – can they encourage growth?

The hair follicles are also active biological structures influenced by signaling pathways, by hormones, by nutrition, and by the general state of health.

The hair cycle includes periods of growth, transition, and rest, and it is influenced by many factors.

Certain peptides are studied for the possibility of influencing the activity of the cells in the follicle and processes related to the growth cycle.

But here it is important to distinguish between three different things:

Strengthening the hair fiber: Peptides and hydrolyzed proteins may be included in hair products intended to improve the feel of the hair, reduce friction, and minimize breakage. This is mainly a cosmetic effect on the existing hair fiber.

Scalp support: Preparations containing peptides may be part of formulas intended for scalp care, but not every peptide has been proven to improve the health of the hair follicles.

Encouraging hair growth: There are peptides being studied in the context of hair growth, but the clinical evidence for most cosmetic preparations is still limited.

Which peptides are common in hair products?

One of the well-known ingredients is Copper Tripeptide-1, related to the copper peptide GHK-Cu.

There are also ingredients such as Biotinoyl Tripeptide-1 and Acetyl Tetrapeptide-3, sometimes combined in preparations intended for thinning hair.

Some of the studies presented for them were performed on mixtures of several ingredients, and therefore it is difficult to know what the contribution of each peptide was on its own.

As of today, there is no sufficient scientific basis to determine that cosmetic peptides are able to regrow hair that was lost in all types of baldness.

In cases of significant hair loss, it is important first to understand what causes it. Iron deficiency, hormonal changes, scalp diseases, stress, and genetic tendency require different approaches.

Can peptides prevent white hair?

The color of the hair is determined mainly by melanin produced in special cells in the hair follicle.

Over the years, the activity of these cells changes, and the reservoir of stem cells related to pigment production may be depleted.

There is preliminary research on molecules and peptides that influence pigmentation pathways, but there is currently no convincing clinical proof that applying peptides to the scalp can reliably prevent age-related graying or restore white hair to its natural color.

Peptides in cosmetics versus drinkable collagen

It is important to distinguish between peptides applied to the skin and collagen peptides consumed by mouth.

When we eat protein, the digestive system breaks it down into amino acids and small peptides, some of which may be absorbed.

Collagen supplements usually contain collagen that has been broken down into smaller parts, called collagen peptides.

A number of studies found a certain improvement in the skin's moisture and elasticity following consumption of collagen supplements, but the quality of the studies varies, and some of them are funded by the industry. Stricter reviews point to uncertainty regarding the size of the benefit.

Regarding hair growth, there is currently no quality evidence proving that collagen supplements treat hair loss.

It is also important to remember that the body needs a varied diet and a sufficient amount of protein in order to produce and maintain tissues. A supplement does not replace this nutritional basis.

Can we get peptides from food?

We consume proteins and peptides naturally through foods such as eggs, fish, legumes, meat, and dairy products.

In the digestive process, the proteins break down, and the amino acids obtained are used by the body to build new proteins.

But eating food that contains peptides is not the same as applying a specific cosmetic peptide.

Each of the routes has a different mechanism of action, and there is no reason to assume that a peptide that is beneficial under laboratory conditions will reach the skin or the hair follicle intact after being eaten.

Are peptides suitable for all skin types?

Most cosmetic preparations containing peptides are generally considered well tolerated.

They do not act like strong peeling acids, and therefore can suit people who prefer a gentle skincare routine as well.

However, a reaction to a product depends on the whole formula and not only on the peptide.

Fragrance ingredients, preservatives, and additional active ingredients may cause irritation or an allergic reaction in some people.

Therefore, it is advisable to test a new product on a small area of skin before extensive use, especially if the skin is sensitive.

Can peptides be combined with vitamin C, retinol, and hyaluronic acid?

In many cases, yes.

Peptides and hyaluronic acid: A combination suited to a skincare routine intended to support moisture and the appearance of the skin.

Peptides and retinol: They can be combined in a suitable formula or at different stages of the routine. Retinoids are among the well-studied ingredients for improving the signs of skin aging.

Peptides and vitamin C: Many types of peptides can be combined with vitamin C, but the stability and suitability depend on the type of peptide, the vitamin derivative, and the acidity of the formula.

There is no scientific rule stating that all peptides must not be combined with vitamin C. It is advisable to rely on the product's instructions and the specific composition.

How do we recognize peptides in the ingredient list?

In the INCI list of cosmetic products, names such as these can be found:

• Palmitoyl Pentapeptide-4
• Palmitoyl Tripeptide-1
• Palmitoyl Tetrapeptide-7
• Copper Tripeptide-1
• Acetyl Hexapeptide-8
• Biotinoyl Tripeptide-1
• Acetyl Tetrapeptide-3

But the mere appearance of the name in the ingredient list does not prove that the product is effective.

The concentration, the stability, the delivery system, and the studies performed on the final formula also influence the possible result.

A product containing ten types of peptides is not necessarily better than a product containing one carefully chosen peptide.

How long until results can be seen?

If it is a product intended to improve the appearance of the skin, possible results are usually examined after several weeks to several months of consistent use.

An improvement in the feeling of moisture may appear faster, but it may also stem from other moisturizing ingredients in the formula.

Changes in the appearance of fine lines, in elasticity, and in skin texture usually require more time.

In hair products, evaluating a change in hair density usually requires follow-up of at least several months, and even then a result cannot be guaranteed.

And what about peptide injections?

In recent years, a market has developed of injectable treatments and preparations sometimes called Peptide Therapy.

It is important to understand that this is a completely different category from cosmetic peptides.

Some peptide-based drugs are approved drugs for certain medical uses, while other substances are marketed without sufficient evidence for safety and effectiveness.

It should not be concluded from the use of peptides in a face serum that peptide injections are a safe or effective treatment for rejuvenating the skin or growing hair.

So are peptides really worth the investment?

I think peptides are an interesting field in the world of skincare, mainly because they make it possible to develop products based on a deepening understanding of the communication between cells.

But as with every active ingredient, the biological potential must be separated from the results proven in practice.

There are peptides that have been studied more than others, and there are products based mainly on marketing promises.

When I examine a skincare product, it is not enough for me to see an impressive word on the packaging. It is important to me to understand what the ingredient is supposed to do, at what concentration it is used, whether it is stable in the formula, and whether there is evidence that the final product indeed provides a benefit.

In summary

Peptides are a natural part of the body's activity systems, and some of them play important roles in communication between cells and in tissue maintenance and repair processes.

In the field of skincare, certain peptides show potential for improving the appearance of the skin, while their use for encouraging hair growth still requires additional clinical research.

They can be an interesting addition to a skincare routine, but they do not replace sun protection, a balanced diet, good sleep, and treatment of medical factors affecting the skin and the hair.

In my eyes, a good skincare product is not measured by the quantity of innovative ingredients on the packaging, but by its ability to provide the skin with what it truly needs.

And the better we learn to understand the ingredient list, the better we can choose products out of knowledge and not only out of promises.

Nurit Rozenblat

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