Peptides and hyaluronic acid often occur together in facial serums, moisturizing creams, and other cosmetic formulations. However, these are chemically distinct ingredients that can perform different functions in the finished product. Hyaluronic acid is a water-binding carbohydrate polymer, whereas peptides consist of amino acids linked by peptide bonds. The effects attributed to a specific cosmetic peptide depend, among other things, on its precise amino acid sequence, chemical modifications, concentration, stability, method of delivery, and the formulation in which it is contained.
Combining peptides with hyaluronic acid can therefore be a rational formulation solution, especially when the goal is to moisturize and improve the appearance of the skin. However, the presence of both categories of ingredients in a single product does not necessarily mean that their combination stimulates collagen production, transports peptides deeper into the skin, permanently remodels tissues, or reduces wrinkles more effectively than any of these ingredients evaluated in a proper comparison.
Research on peptides and hyaluronic acid also covers very different types of interventions. Some involve traditional serums or creams applied topically, others evaluate multi-stage skincare regimens, and still others utilize specially designed delivery systems or micro-needle patches containing hyaluronic acid. These display methods should not be treated as equivalent.
For example, a study in which participants use a serum containing hyaluronic acid together with a cream rich in peptides is evaluating just this specific regimen.[1] It does not automatically constitute evidence regarding any serum available on the market labeled „multi-peptide + HA”.
Therefore, when interpreting claims about combined products, it is crucial to understand what each component contributes, how hydration and the appearance of wrinkles are measured, and what conclusions can actually be drawn from a specific study design.
Peptides and hyaluronic acid
Two different types of molecules
A peptide consists of amino acid residues linked by peptide bonds. A change in even a portion of the amino acid sequence can affect the chemical properties and biological behavior of the molecule. Chemical modifications, including the attachment of lipid or other molecular structures, can further alter properties such as stability or retention in formulation.
Therefore, the term „peptide” describes a broad category of molecules, not a single standardized cosmetic ingredient.
For example, a study involving humans on palmitylated pentapeptide in a moisturizing formulation provides data related to that particular peptide and the formulation in which it was tested.[2] It does not prove that any other peptide will produce the same effect just because it is also a member of the peptide family.
Hyaluronic acid, also known as Hyaluronic acid, It belongs to a completely different chemical class. It is a polysaccharide made up of repeating sugar units, not amino acids.
Hyaluronic acid itself also does not exist in cosmetics as a single, always identical material.
Its molecular mass can vary significantly, and chemical processes can lead to the formation of materials with different properties. Sodium hyaluronate it is a form of salt commonly found on lists of cosmetic ingredients, whereas hydrolyzed and crosslinked forms introduce further differences in structure and behavior.
Controlled studies comparing hyaluronic acid with different molecular weights show why the exact material characteristics matter. [3]
For someone comparing products, the practical conclusion is simple: the claim regarding the peptide should, as far as possible, indicate the peptide. specific peptide and the evidence related to it, However, the claim regarding HA should take into account the type of hyaluronic acid used and the formulation in which it is found.
The very name of any of these ingredients does not yet tell us about the concentration, stability, method of delivery, tolerance, or clinical effectiveness of the finished product.
Does hyaluronic acid help peptides penetrate through the skin?
Hyaluronic acid should not be automatically presented as a universal carrier that transports every peptide present in the formula through the skin barrier.
Delivery of substances through the skin is a much more complex process.
In one of the experimental studies on HA-related transport, the observed effects depended, among other things, on the molecular mass of hyaluronic acid and whether the skin barrier was intact or damaged. [4] Importantly, the model substance transported was bovine serum albumin, a protein, not a typical cosmetic peptide.
The study therefore shows that transport associated with HA may depend on the molecular properties and the state of the skin barrier.
However, it does not support the much broader claim that adding hyaluronic acid to any peptide serum automatically transfers the peptide to the living layers of the skin.
Another study approached the issue of transportation from the opposite side. Scientists developed a specially designed a carrier system that uses the SPACE peptide to deliver hyaluronic acid. [5] This was a specialized technology for delivering assessments, evaluated in skin experiments and in an animal model, rather than a standard clinical study of facial serum.
This is an important distinction.
A specially designed peptide system designed to change the transport of substances cannot be considered proof that a regular cosmetic product containing both HA and a peptide behaves in the same way.
The co-presence of the ingredients in a formulation and the proven delivery of them to the skin are two separate scientific claims.
Moisturizing and acting on the surface of the skin
What can provide moisture to the skin surface?
Formulations containing hyaluronic acid can affect the water-binding properties of the outer layers of the skin and contribute to the formation of a film on its surface. These effects can make the skin appear softer and smoother, and fine surface lines become less visible.
These are significant cosmetic effects.
It is not necessary to present them as a lasting structural transformation to consider them valuable.
At the same time, the hydration of the skin surface should not be equated with evidence of the formation of new collagen in the epidermis. A slight line may temporarily become less visible due to better hydration of the outer layers of the skin without any evidence that deeper tissue has been permanently remodeled.
In a six-week study involving 40 women, locally applied HA serum was evaluated. An increase in instrumentally measured hydration was noted, along with improvements in selected skin appearance parameters. [6] The participants also used sunscreen cream, and the abstract of the publication did not describe a control group receiving the base product alone.
The study therefore provides information regarding the observed pattern of care and the course of changes over time, However, it provides less certainty as to which part of the improvement was specifically due to HA, and which part was due to the serum formulation, additional skincare, or other factors.
Such terms as "incompatible with" should be interpreted with equal caution. „immediate” or „long-lasting”.
Instrumental measurements performed shortly after applying the serum can record the immediate hydration of the surface and the effect of the film formed on the skin. Measurements performed after several weeks of regular use answer another question.
None of these measurements alone determines how long the effect persists after the product is discontinued.
Demonstrating durability would require an appropriately planned observation period or withdrawal phase during which measurements would be performed after the product has been used under conditions allowing a reliable comparison.
Molecular mass matters, but it does not create a universal ranking
The molecular mass of hyaluronic acid can affect its physical properties and stability in the formulation, which is why the particle size is scientifically important.
However, this issue should not be reduced to a simple principle that the smaller the HA molecule, the better.
In a controlled study involving 76 women, creams containing HA preparations with different molecular weights were compared with a backing applied to the opposite area around the eye. [3] The HA-containing formulations improved hydration and elasticity, while significant improvement in wrinkle depth was described for specific preparations with lower molecular weight.
These results support the hypothesis that The properties of the material can influence the specific measured effects.
However, this does not mean that the HA product with the lowest available molecular weight will always be the best for every formulation, site on the skin, or population.
In another randomized study involving 36 elderly individuals with dry skin, HA with a low molecular weight, HA with a high molecular weight, and a base applied to different areas of the legs were compared.[7]
The product with a low molecular weight achieved better results in terms of Electrical capacitance of the skin, which is a measure related to hydration. However, no significant differences were found between the groups in terms of TEWL or the evaluated symptoms.
This is a particularly instructive example, because it shows that one formulation can achieve a better result for a specific parameter without showing an advantage in all other measurements.
The molecular mass is therefore important, but it must be interpreted in relation to the specific formulation and the effect being examined.
Moistening is not the same as limiting water loss
Measurements of moisture and transcutaneous water loss are sometimes discussed together, but they describe different properties of the skin.
Techniques such as electrical capacitance measurement or corneometry allow for estimating properties related to the water content in the outer layers of the skin.
Transcutaneous water loss, or TEWL, It determines the amount of water that passes through the skin into the surrounding environment under specific measurement conditions.
A moisturizing product can improve skin hydration results without causing a statistically detectable change in TEWL.
A good example is the aforementioned randomized HA study in people with dry skin. The low molecular weight formulation achieved better results in the hydration-related measure, but this advantage did not translate into a significant difference between the groups in the TEWL measure. [7]
This distinction is particularly important when assessing the definition. „support for skin barrier”.
A higher level of hydration may be important for the comfort, softness, and appearance of the skin surface, but it should not automatically be presented as proof of complete barrier repair if the appropriate parameters related to the barrier's function do not confirm this.
The inverse relationship also applies.
The change in TEWL does not prove that the peptide has penetrated the living layers of the skin, activated a specific signaling pathway, or increased collagen synthesis.
Different measurements answer different questions.
Multicomponent serum
What does „multi-peptide + HA” really mean?
Term „multi-peptide + HA” It usually informs the consumer that the formulation contains more than one peptide component together with hyaluronic acid or another material belonging to the group of hyaluronic acids.
This is not a standardized scientific category or a scale of effectiveness.
Two products that use almost identical terms on the label can contain completely different peptide sequences, different molecular weights or HA derivatives, different peptide concentrations, and very different excipients.
They can also differ in the delivery system.
The mere term „multi-peptide + HA” therefore does not indicate which component would be responsible for the potential measured effect.
Scientifically useful product description should as accurately as possible identify the finished formulation, specify the expected cosmetic effect, and distinguish between different types of cosmetics. evidence obtained for the complete product from data regarding the individual components.
The number of peptides in the formulation does not replace a comparative clinical study.
Similarly, separate studies concerning several individual components cannot simply be mathematically or conceptually summed up to predict the magnitude of the effect of the finished product.
Direct data regarding the combined care plan
In a 12-week study, the evaluation was carried out serum based on hyaluronic acid used together with a cream rich in peptides in people with features of photodamage of the skin of the face and neck. The study included 17 participants. The researchers described improvements in several parameters related to the appearance of the skin and favorable tolerability, as well as the absence of adverse effects attributed to the products being studied. [1]
This is directly relevant evidence regarding the scheme used exactly in the way it was used in the study.
However, the research project imposes significant limitations on the ability to attribute the effect to individual components.
Without separate groups using the HA serum alone, the rich peptide-rich cream and the appropriate control product cannot be determined whether the combination worked better than any of the products used separately.
It also cannot be concluded that a specific peptide was responsible for the observed change.
This is the fundamental difference between demonstrating that The use of the entire scheme was associated with an improvement, and proof that one of its ingredients provided an additional benefit.
The small number of the study is also important for interpreting tolerance. The absence of reported adverse reactions associated with the product in this group is useful information, but it does not allow the exclusion of rare reactions that could occur in a much larger population.
A stronger study of the additional component should maintain the basic formulation as unchanged as possible, modifying primarily the component under analysis.
A stronger claim regarding synergy would require an experimental design and analysis that would demonstrate that the combination produces an effect greater than the corresponding defined expectation resulting from the action of the individual components.
The same positive results before and after the use of the product cannot confirm any of these claims.
What do the biopsies show, and what can they not prove?
Some studies of multi-ingredient products analyzed, in addition to the appearance of the skin, also biological markers.
In a multicenter study, serum containing peptides containing HA was evaluated over an eight-week period. The researchers described the clinical observations and collected biopsies from seven participants. In this small subgroup, the increased levels of HA were observed in the serum samples of all participants. CD44 expression in staining six people were noted, along with an improvement in the parameters of the solar elastosis. [8]
These results are more biologically specific than the satisfaction survey, but they still require precise interpretation.
CD44 is a receptor associated with the biology of hyaluronic acid. However, increased CD44 staining is not the same as direct evidence of increased synthesis of new hyaluronic acid.
It also does not prove independently that the peptide was responsible for the change.
The group in which biopsies were performed was very small, and the entire study was open-label. Without appropriate controls to isolate the effects of individual components, the causal mechanism remains uncertain.
The most reasonable conclusion therefore is that The formulated substance under study yielded biologically interesting results that require further research.
Much stronger and unsupported by this study would be the statement that all serums containing HA and peptides regenerate or repair the skin.
When the delivery method changes the research question
The way in which a cosmetic ingredient or research material reaches the skin can be just as important as the list of ingredients itself.
In a randomized controlled trial, the evaluation was conducted micro-needle patches with cross-linked hyaluronic acid, containing acetyl hexapeptide-8 or epidermal growth factor. The study included 50 participants, and patches with additional active ingredients resulted in greater improvement in selected wrinkle parameters than the base patch under the study conditions. [9]
This constitutes evidence regarding a specific micro-needle platform.
It should not be directly applied to traditional surface-applied serums.
Microneedles physically change the delivery environment and can create exposure conditions that conventional application to intact skin does not replicate.
The manufacturer of a classic serum cannot simply transfer the results of the micro-needle test just because his product also contains hyaluronic acid and a peptide.
The delivery route, the design of the device, the formulation and the nature of the display are integral elements of the intervention being studied.
These are not secondary technical details.
Humidity measurement and assessment of the appearance of wrinkles
What do the most important endpoints mean?
Different skin testing methods provide different information, and no single parameter describes all aspects of skin appearance or skin biology.
Electrical capacitance measurements or corneometry help assess the properties related to the water content in the outer layers of the skin. However, they do not in themselves indicate the formation of new collagen, peptide penetration, or permanent structural remodeling.
TEWL allows the assessment of water loss through the skin under controlled conditions, but the result itself does not indicate which component of the formulation was responsible for the observed change.
Clinical assessment of wrinkles can determine their apparent severity according to a defined scale, but it does not automatically identify the molecular mechanism responsible for the difference.
Surface imaging or profilometry can analyze the surface shape, roughness, or line dimensions, but they do not indicate whether the improvement will persist after the product is discontinued.
The participant's assessment provides information regarding perceived softness, comfort, or appearance, but does not replace the blind, objective assessment of effectiveness.
Biopsies and tissue markers, however, allow the analysis of selected biological properties of the extracted tissue, but without appropriate controls they do not prove the benefits for the entire face or the action of a specific component.
These measurements can complement each other, but they should not be used interchangeably.
HA studies illustrate this well. Moisture measurements, wrinkle assessments, and tissue markers can describe different aspects of the skin's response.[3][7][8]
Better interpretation shows how the individual results complement each other, rather than replacing them with a broad term such as „skin rejuvenation”.
Why do photographs require proper inspection?
Photographic documentation can be useful in skin care research, but the way the photographs are taken should be standardized.
Lighting, camera distance, angle, facial expression, head position, and image processing can all affect how visible wrinkles, shadows, and skin texture are.
A convincing „before and after” photo can document the visible difference, but by itself it does not allow determining which component caused it.
For multicomponent formulations, stronger evidence therefore includes appropriate control groups, standardized supportive care, and, if possible, blinded evaluation.
Administration the magnitude of the observed difference along with its uncertainty it is also more informative than the mere statement that the result achieved statistical significance.
A very small difference can sometimes be statistically significant, but at the same time it is difficult for participants or independent observers to notice it.
Statistical detectability and the apparent significance of the effect are not always the same thing.
Claims of structural changes require structural evidence.
Statement „the skin looks more filled in” it is not equivalent to a statement „the skin has rebuilt its structural support”.
The first claim can be reasonably examined through measurements of moisture, imaging of the skin surface, or evaluation of appearance.
The second requires evidence relating to the specific structural change claimed, an appropriate period of observation, and a study design that allows the effect to be attributed to a specific cause.
Moistening alone does not fill this gap in the evidence.
Even measurements performed at the tissue level must be interpreted in accordance with what they actually measure.
A good example is the results regarding CD44.[8] Increased expression of a biologically relevant receptor in staining is an interesting scientific observation, but directly converting it into a broad claim about the regeneration of native skin would go beyond the scope of the measurement itself.
The scientific description should therefore to actually call a measured parameter instead of replacing it with a broader marketing interpretation.
Limitations of evidence and formulations
The formulation and the studied population determine the scope of application of the results
The significance of a cosmetic study depends, among other things, on how closely the tested population, the area of the body, the formulation and method resemble the product and the method of use that we want to draw conclusions from.
Data obtained on dry skin of the ankles in older adults may provide valuable information about hydration, but they are not automatically equivalent to the peptide serum study used on the face in younger participants.
Similarly, eye cream, a full facial skincare regimen, classic serums, and a micro-needle patch cover different application sites, exposure conditions, and delivery mechanisms.
Therefore, when evaluating the study, attention should be paid to the exact formulation, the comparator product, the characteristics of the participants, the duration of the intervention, and the definition of each endpoint.
It is also worth determining whether all participants included in the study were included in the analysis, whether they used additional cosmetics, and whether the finished product was evaluated or only the experimental model component.
If only an abstract is available and the important methodological details are not provided therein, they should remain unknown.
They should not be supplemented with assumptions.
Method of administration and tolerance
There is no scientifically established, universal order of application that can be deduced solely from words. „peptide” and „hyaluronic acid”.
Water-based serum, emulsion, moisturizing cream, and micro-needle patch are essentially different formulations and may have different instructions for use.
Research on a single product does not prove that every cosmetic containing peptides and HA requires a specific order of application, waiting time, or application on wet skin.
The method of use should therefore remain the same a ready-made formulation that has actually been developed and tested, Instead of being presented as a universal property of the entire category of components.
Tolerance also depends on the complete composition of the product.
A study indicating good tolerability in a small group does not prove that every other formulation containing HA and peptides will be equally well tolerated, especially when it comes to the elderly.