Vitamin C Serum: Benefits for the Face, Mechanism of Action, and Stability Testing
Vitamin C serum is one of the most popular skincare products because it is often associated with brighter looking skin, reduced dullness, and added protection against environmental exposure. However, behind these product claims, skincare brands need to pay attention to one important factor: formula stability.
Vitamin C is an active ingredient that can be sensitive to light, air, temperature, and storage time. That is why understanding the benefits, how it works, and the importance of vitamin C serum stability testing can help brands ensure their products remain high quality until they reach consumers.
Table of content:
- Vitamin C and Its Popularity in the Skincare Industry
- Stability of Vitamin C in Skincare Formulations
- Measurement of Vitamin C Antioxidant Activity
- Why Vitamin C Remains a Leading Choice
- Selection and Use of Vitamin C Serum
Vitamin C and Its Popularity in the Skincare Industry
Vitamin C is one of the most popular active compounds in modern skincare. It was first recognized as an essential nutrient for preventing scurvy caused by vitamin C deficiency in the body.
In dermatology and cosmetics, vitamin C later became a leading active ingredient due to its ability to maintain skin health and improve skin appearance. In topical skincare formulations, vitamin C functions as an antioxidant that helps protect the skin from damage caused by free radicals, pollution, and ultraviolet (UV) exposure.
In addition, vitamin C is well known for its skin brightening effects because it can inhibit the activity of the tyrosinase enzyme involved in melanin formation. Therefore, the use of vitamin C serums is often associated with improvements in hyperpigmentation, reduction of dark spots, and enhanced skin radiance.
Another important function of vitamin C is its role in supporting collagen synthesis in the skin. Collagen is a structural protein responsible for maintaining skin elasticity and firmness. By increasing collagen production, the skin can appear healthier, while signs of premature aging such as fine lines may become less visible.
Stability of Vitamin C in Skincare Formulations
Despite its wide range of benefits, vitamin C is considered a relatively unstable compound. This characteristic is closely related to its antioxidant nature. Antioxidants work by donating electrons to neutralize free radicals, making the compounds themselves more susceptible to oxidation.
The most commonly used form of vitamin C in skincare is ascorbic acid, also known as L ascorbic acid. This form is considered the most biologically active, but it is also the most prone to degradation when exposed to light, air, high temperatures, and pH changes.
When oxidized, vitamin C serums typically change color from pale yellow to dark yellow or brownish tones. This color change is often an indicator that the activity of vitamin C has decreased.
To address stability issues, the cosmetic industry has developed various chemically modified vitamin C derivatives, such as sodium ascorbyl phosphate, magnesium ascorbyl phosphate, and ascorbyl glucoside. These derivatives offer greater stability against heat and light compared to pure ascorbic acid.
Although their activity may act slightly more slowly, vitamin C derivatives are generally more stable during storage and are often more suitable for sensitive skin.
Read also:
Understanding Vitamin Benefits: Ensuring Efficacy, Safety, and Market Strategies
Measurement of Vitamin C Antioxidant Activity
The antioxidant activity of vitamin C can be evaluated using several scientific methods. One of the most commonly used parameters is the IC50 value. IC50 refers to the concentration of a compound required to inhibit 50% of free radical activity.
The lower the IC50 value, the stronger the antioxidant activity. For example, compounds with IC50 values below 50 ppm are generally categorized as having very strong antioxidant activity. Values between 50–100 ppm are considered strong, while higher values indicate weaker antioxidant activity.
IC50 testing is commonly performed using the DPPH method, which measures the ability of a compound to neutralize purple colored free radicals. In addition to the DPPH method, other analytical methods include the ABTS assay, FRAP assay, and ORAC assay.
The ABTS method measures antioxidant capacity against radical cations, while FRAP evaluates the ability of antioxidants to reduce metal ions. ORAC focuses more on assessing antioxidant protection against biological oxidation. These various methods are used to ensure the effectiveness of active ingredients in skincare formulations.
Why Vitamin C Remains a Leading Choice
Many other compounds also provide skin brightening benefits, such as niacinamide, arbutin, kojic acid, and tranexamic acid. However, vitamin C continues to be one of the most widely used active ingredients today.
Based on numerous dermatological publications, the popularity of vitamin C is influenced by several factors. First, vitamin C has a broad mechanism of action because it functions not only as a skin brightening agent, but also as an antioxidant and collagen stimulator.
Second, vitamin C molecules are relatively small, allowing them to penetrate the skin effectively, especially in serum formulations with appropriate pH levels. Additionally, vitamin C has a strong scientific reputation because it has been extensively studied in dermatology journals for decades.
From an economic perspective, vitamin C raw materials are also relatively easier to produce compared to several other more complex active compounds.
Selection and Use of Vitamin C Serum
As consumers, selecting the appropriate type of vitamin C should be adjusted according to skin condition. Pure ascorbic acid is more suitable for users seeking high effectiveness in brightening the skin.
However, for sensitive skin, more stable vitamin C derivatives may provide a safer option. Vitamin C serum is generally applied in the morning or evening after cleansing the face. For morning use, vitamin C is often combined with sunscreen because it can help enhance skin protection against free radicals generated by sun exposure.
The stability of vitamin C serum is evaluated not only through antioxidant activity but also by observing color, odor, pH, and active ingredient content during storage. Oxidized vitamin C serum usually changes color to dark yellow or brown and shows reduced effectiveness.
Therefore, storing the product in airtight containers protected from light is essential to maintaining product quality. With the advancement of cosmetic formulation technology, vitamin C continues to remain a leading active ingredient widely used in modern skincare due to its broad range of benefits for skin health.
Bright Claims Need Proof
If your brand is developing a vitamin C serum, do not focus only on claims such as “brightening” or “antioxidant” on the packaging. Make sure the formula remains stable, safe, and consistent throughout its shelf life.
With IML Testing and Research, you can conduct professional product stability testing to support product quality, claims, and consumer trust in your skincare brand.
Author: Delfia
Editor: Alphi
References
Al-Niaimi, F., & Chiang, N. Y. Z. (2017). Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. The Journal of clinical and aesthetic dermatology, 10(7), 14–17.
Sasidharan, O., Gholap, A., & Rastogi, R. (2023). A Review of Clinical Efficacy of Topical Vitamin C and Its Derivatives. Pharmaceutical Science and Technology.
