Criteria for Choosing a Polypeptide — What to Look at in the Full Ingredient List

The first problem encountered when choosing a product containing polypeptide is, 'the names are similar, but what's actually different?' Since the full ingredient list does not indicate content percentages, it is difficult for consumers to judge the merits of an ingredient based solely on the word polypeptide.

However, under cosmetics law, the full ingredient list must be written in descending order of formulated amount, and there is still enough basis to infer the purpose behind an ingredient's inclusion simply from how the ingredient name is labeled and which accompanying ingredients are combined with it. This article organizes the 'criteria for choosing' polypeptide into four branches: labeling name, placement position, accompanying ingredients, and formulation type.

What is polypeptide, and why are criteria needed

Peptide is a general category referring to substances made of short chains of amino acids, categorized and labeled as oligopeptide, polypeptide, etc., depending on chain length or structure. In the cosmetics industry, this peptide family of ingredients is often used in formulation design for elasticity care purposes.

The problem is that the name 'polypeptide' itself is an extremely broad category. Even just among labeling names registered in the International Nomenclature of Cosmetic Ingredients (INCI), there are many types, and depending on the number or code attached afterward, they actually refer to completely different raw materials. Therefore, judging a product based solely on the phrase 'contains polypeptide' is an approach with far too little information.

This is why criteria are needed. In a situation where the content percentage cannot be known, looking at both the specificity of the labeling name and the formulation context together is realistically the most precise method of judgment available.

Criterion 1 — Is the labeling name specific?

The first thing to check is whether the full ingredient list simply states 'polypeptide' in a general way, or whether it specifies a concrete designation with a prefix and number, such as 'rh-Polypeptide-1'.

A concrete designation means the raw material is a specific substance registered according to international standard nomenclature rules. The prefix (such as rh) can be understood as part of a notation system that distinguishes whether the polypeptide was made through a recombinant method and what structural characteristics it has. The more specific the designation, the more directly consumers can verify and search for what the ingredient actually is, so the specificity of the designation itself can serve as one criterion for judgment.

Criterion 2 — Where does it appear in the order of the full ingredient list?

The second criterion is where the polypeptide appears in the full ingredient list. Since ingredients are listed in descending order of formulated amount, appearing earlier in the list can be seen as reflecting a relatively greater proportion in the formulation.

However, it often appears in a middle position — after base ingredients like water and glycerin, but before trace-amount ingredients — which can be understood as consistent with the characteristic of polypeptides generally being precisely formulated in small amounts as active ingredients. If the position is too far toward the end, it may be worth keeping in mind that the inclusion could be more symbolic.

Criterion 3 — What ingredients is it combined with?

The third criterion is to look not at the polypeptide alone, but at the combination of ingredients it is formulated with. For example, if it is combined with Centella asiatica-derived ingredients (asiaticoside, madecassic acid, asiatic acid), this can be read as a design that also considers soothing care; if combined with barrier lipid ingredients such as ceramide NP, cholesterol, and palmitic acid, this can be read as a design that also considers barrier care.

It is also an important point to check whether the polypeptide is combined with an ingredient such as adenosine, which the Korea Ministry of Food and Drug Safety has recognized as a notified ingredient for functional cosmetics for wrinkle improvement. Since notified ingredients are items that have undergone review and are permitted for labeling and advertising, checking whether the polypeptide's elasticity-care direction and adenosine's functional review scope are present together in the same formulation can give a more concrete sense of the design intent.

Criterion 4 — Does the formulation stably hold that oil-related feel?

The last criterion is the formulation itself. Active ingredients like polypeptides must be stably maintained within the formulation in order to preserve their form until they reach the skin. In this regard, whether oil-based ingredients such as squalane, shea butter, argan kernel oil, and olive oil are included together can serve as one reference indicator.

Oil-based ingredients play a role in holding moisture in place so it does not evaporate, and richer cream-type formulations tend to have a greater proportion of such oil-based ingredients. If moisturizing and soothing ingredients like panthenol and allantoin, along with moisture-retaining ingredients like betaine and trehalose, are formulated together, this can be understood as a conditioning layer designed to surround the active ingredient.

Applying these four criteria together

In summary, the criteria for choosing a polypeptide can be divided into four categories: ① the specificity of the labeled name ② the formulation position ③ accompanying ingredients (Centella asiatica-derived ingredients, barrier lipids, notified functional ingredients) ④ the oil feel of the formulation. If a consistent direction is visible when looking at these four together, that can serve as grounds for judging that the product incorporated the polypeptide not as a standalone ingredient but as one axis of the overall design.

Conversely, if the labeled name is vague and the connection with accompanying ingredients is also unclear, the possibility that it is closer to a marketing mention cannot be ruled out. Within a full ingredient list that has no percentage figures, cross-checking these four points is realistically the most concrete method of judgment available.

Checking Through the Full Ingredient Design

Individual Differences and Precautions

The way any ingredient, including polypeptides, feels can differ depending on skin type and condition. Even products with the same full ingredient list may differ from person to person in usage feel or absorption speed, and this falls within a normal range.

If abnormal reactions such as redness or itching persist during use, it is safer to stop use and consult a dermatologist or other specialist. It is also worth remembering that checking the full ingredient list is a useful tool for understanding ingredients, but it does not substitute for actual skin reactions.

The Final Step, Which Cream to Finish With

After going through these four criteria in order, the question that naturally remains is 'then is there a product where these four strands are actually consistently designed?' Applying this framework to the full ingredient list of 에르쯔틴 리제너레이티브 실트 크림, the specific labeled name RH-Polypeptide-1 is positioned in the active ingredient section after purified water and glycerin-type ingredients, surrounded by three types of Centella asiatica-derived ingredients and adenosine, while oils such as squalane, shea butter, argan kernel oil, and olive oil, along with ceramide NP and cholesterol-series ingredients, are contained together within a rich cream formulation meant for the final step. Examining whether the four criteria—labeled name, position, accompanying ingredients, and formulation—do not contradict one another within a single full ingredient list is, in a sense, the most concrete method for choosing a polypeptide.