Vitamin C is often regarded as a wrinkle fighter or an anti-aging agent. The main objective of Vitamin C skin care, in scientific terms, is to increase the synthesis of collagen (a structural protein that is found in skin). The additional benefit of Vitamin C skin care is related to its capability of countering free radicals which cause damage to the skin.
Vitamin C skin care, however, faces a major challenge today. This is related to the oxidation tendency of Vitamin C skin care products. On coming in contact with any oxidising agent (e.g. air), the Vitamin C in the Vitamin C skin care products, gets oxidised; thus making the Vitamin C skin care product useless (in fact counter-effective). The oxidised Vitamin C imparts a yellowish-brown colour to the Vitamin C skin care product. This is something that you need to check before buying a Vitamin C skin care product. Even after you buy a Vitamin C skin care product, you need to store it properly and keep checking that its still good to use (i.e. it hasnt attained a yellowish-brown texture).
The manufacturers of Vitamin C skin care products have tried to deal with this (oxidation) problem in multiple ways (and research on Vitamin C skin care products is on the top of their list). One such method of retaining effectiveness of Vitamin C skin care products for a long term is to keep a high concentration (say 10%) of Vitamin C. However, this makes the Vitamin C skin care products even more expensive. The Vitamin C skin care products are already pretty inexpensive and making them even more expensive will throw the product manufacturers out of business. The other way is to use Vitamin C derivatives (like ascorbyl palmitate and magnesium ascorbyl phosphate). These are not only more stable but also inexpensive. Even though the derivatives based products are not as effective as the Vitamin C skin care products, their stability against oxidation is a very desirable feature that makes them very attractive. Moreover, these are known to be less irritating too.
Talking of effectiveness of Vitamin C skin care products, its important to mention that not everyone responds to Vitamin C treatments. So its not a magic potion in any way. If you dont see a noticeable difference in your skin, it might be because of your skin not responding to Vitamin C treatment (and the Vitamin C skin care products might not be at fault, at all).
As more research goes on, one can only keep our fingers crossed and wait for a complete solution to the challenges faced by Vitamin C skin care today.