Vitamin C serums have taken the skincare world by storm and are viewed as some of the best anti-aging, brightening, and skin-protecting actives available. Amidst all of the various products and hype, consumers may not know how to decipher the products that actually do what they claim from the marketing.
In an evidence-based fashion, this article will explore “Vitamin C Serums: What Works and What is Marketing” in terms of the science behind vitamin C, the key ingredients, formulations and what to know when shopping.
The Science behind vitamin C and skin health
Vitamin C (also known as ascorbic acid) is a potent antioxidant that occurs naturally in the skin. The Journal of Cosmetic Dermatology published a systematic review in 2023 which found topical vitamin C was an effective treatment for photoaging (sun damage), hyperpigmentation (uneven skin tone) and melasma. The review further found that a key finding was a smoother skin appearance, and lower wrinkle density with topical treatments, and evidence that topical vitamin C treatments could lead to significant lightening of pigmentation over time.
A report from the National Library of Medicine highlights that vitamin C has been shown to stimulate collagen synthesis, stabilize collagen fibers in the skin, and protect skin from oxidative stress associated with UV exposure. Collagen is critical for skin firmness and elasticity and is a major contributor to wrinkling and sagging of the skin when degraded.
What vitamin C serums actually do
Vitamin C serums work primarily to neutralize free radicals (unstable molecules created by UV damage, pollution, and metabolism) that accelerate skin aging. Additionally, vitamin C serums inhibit melanin production to improve skin brightness and lighten dark spots. Finally, vitamin C is shown to support skin repair by increasing collagen production, improving hydration to the skin and reducing skin inflammation.
Most importantly, while there is much advice on the use of vitamin C orally versus topically, vitamin C is shown to be more effective when applied topically, particularly in regard to photoprotection effects. Vitamin C is taken up by the skin which becomes more effective at delivering antioxidants to the layers of the skin where free radical damage occurs. Topical vitamin C is even more effective when it is combined with other antioxidants such as vitamin E and ferulic acid, where it confers protection against damage from UV exposure more effectively than vitamin C alone.
What consumers need to know about formulation
Vitamin C formulations are not all created equal. The effectiveness of a vitamin C serum is largely determined by formulation, concentration, and packaging:
- Form of Vitamin C: L-ascorbic acid is the most active and studied form of vitamin C, but it is unstable and can oxidize relatively quickly. More stable alternatives are used such as magnesium ascorbyl phosphate and sodium ascorbyl phosphate, but these may not be as potent as L-ascorbic acid.
- Concentration of Vitamin C: Often vitamin C serums are at a concentration between 10-20% vitamin C. Concentrations below 10% do not appear to have the same effectiveness, and concentrations above 20% do not confer any added effectiveness and may lead to skin irritation.
- pH level: Vitamin C is effective in a more acidic environment, a reported pH range of 3.0 to 3.5 appears to be ideal for effectiveness. Formulations outside of this range may be less effective.
- Packaging: The biggest issue with a vitamin C serum is that it will oxidize with exposure to the air. A bottle that is opaque (dark), air-tight (glass with a dropper or pump) will generally prevent oxidation to a greater degree than a pump bottle or a clear bottle.
Common marketing claims: What to watch for
Many serums claim benefits of “anti-aging,” “skin brightening,” or “wrinkle reduction,” often based on client testimonials rather than solid research. There are several marketing traps to be aware of, including:
Concentration confusion: Some products will include derivatives of vitamin C without sharing the active amount.
- Claiming immediate results: It should be noted that effective vitamin C serums often require a few consecutive weeks or months of consistent use to work.
- Celebrity endorsement reliance: Just because a celebrity endorses a product does not mean it works.
- No other antioxidants: Vitamin C works best when combined with vitamin E and ferulic acid, to stabilize the vitamin and improve effectiveness.
- Potential skin irritation: Higher strength serums can irritate sensitive skin and possibly prevent clients from using the product continuously.
How to use a vitamin C serum
Apple’s team of skincare advisors, as well as dermatologists, generally recommend applying vitamin C serums to clean, dry skin once per day, preferably in the morning before sunscreen use. The main reason to apply vitamin C in the morning is to help enhance the effectiveness of sunscreen, as well as to provide added photoprotection.
Be careful not to layer the serum with acids (like glycolic acid or salicylic acid) or retinol, if possible, during the day where the risk of irritation is heightened. It would be best to apply the serum while allowing it to absorb for hydration helper products to follow.
Science-based choices for your skin
In conclusion, vitamin C serum, when formulated correctly and consistently used, is useful for several important skin benefits. There is a relatively wide body of evidence supporting the effectiveness of vitamin C serums in combating photoaging, hyperpigmentation, and uneven skin tone, assuming the concentration of L-ascorbic acid and pH level is in an optimal range (10-20%, low pH) and other antioxidants are included in the formulation. The packaging is also a piece of this puzzle that cannot be ignored.
Finally, and as addressed throughout the article, while marketing can undoubtedly take the science out of the product and can muddy the waters for the consumer, there is substantial evidence to support vitamin C’s role in tackling photoaging, hyperpigmentation, and uneven skin tone – this is not just from a marketing perspective.
With this knowledge and understanding of realistic outcome expectations, considering a good vitamin C serum could be the foundation of a healthy skin routine, backed by science as opposed to an advertisement.