Vitamin C is one thing that has made a significant impact on my skin. Read on for more info.
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There's a ton of information and misinformation on using topical vitamin C - collagen boosting, scar fading and healing, wrinkle busting etc. And then there's the debate on what form of vitamin C is best - water soluble ascorbic acid, or fat soluble ascorbyl palmitate? Here's a reasonable article on vitamin C. But in the end, the proof of the pudding is in the eating. Does it do what is claimed?
Short answer, it fades scars, brightens up the skin. I can only show you proof of the first as the 2nd claim requires precise photography at similar exposure etc. to demonstrate.
Above is a close up shot of my cheek - I apologize for the gory details of all the imperfections. The picture on the right is the before picture with a little scar from a blackhead in the center. The picture on the left is the after picture - the scar is very visibly diminished, (though there's a new one below). I had had the scar (that's faded) for at least 6 months. I started using my vitamin C serum late August and I think it took about three months to fade completely. So I think the serum definitely helped.
However not all vitamin C serums are created equal. Ascorbic acid is notoriously unstable in the presence of water and oxygen. It also needs to be highly concentrated (at least 20%) to work. This means one needs to be very careful when choosing a vitamin C serum. How do you do that? For starters look at the ingredients and make sure ascorbic acid is listed right after water. If it's somewhere in the bottom of the ingredient list, don't waste your money. Secondly, if you want to be nerdy, check the pH (pH paper is pretty inexpensive and can be used to test a variety of things at home). However this can only be done after you've bought the serum. The pH should be lower than 4 to be effective. Just for laughs, I measured the pH of things with some acids that are good for skin - ascorbic, citric, lactic acid.
Lemon and my vitamin C serum have the lowest pH at 3. Fresh orange juice has a pH of 5 and yogurt a pH between 5 and 6. So clearly lemon and my vitamin C serum are most potent.
After using the serum now for more than 4 months pretty much every night, below are my conclusions.
1) It fades scars - takes a couple months to disappear.
2) Acts as a good cleanser - I can visibly see the dirt on the cotton ball even after I've washed my face with soap.
3) Brightens face. This does NOT mean whiten. It makes it look less dull than it used to be. This is because acids are good exfoliators.
Regarding stimulating collagen production - don't know as I can't test for that. One last thing - if you are using a concentrated vitamin C serum, use it only at night as increased levels of ascorbic acid can make your skin extremely photosensitive.