Vitamin C, also called ascorbic acid, is a popular natural ingredient used in skin care cosmetics. There are two mechanisms by which it can affect your skin.
First, vitamin C is an essential component for collagen synthesis. Without adequate vitamin C, the collagen in your skin would be malformed and your skin and gums would not heal properly. This is obvious in patients who are clinically deficient of vitamin C, a condition called scurvy. Among other problems, scurvy patients have bleeding from their gums and poorly healing wounds.
Secondly, vitamin C is a potent antioxidant. Like other antioxidants, it helps to prevent skin damage and wrinkles by soaking up harmful free radicals.
The problem is how to get the vitamin C into your skin. Your skin is designed to keep things out (on the whole, a good idea), but this makes getting medications and creams below the surface, where they exert their effects, rather difficult.
In order for vitamin C to penetrate the skin, it needs to be in an acidic environment, and it needs to be in a high concentration in the product. Unfortunately products that contain 5-10% ascorbic acid are expensive and it’s unlikely that products with low amounts of ascorbic acid have any measurable impact on your skin.
In addition, topical vitamin C is highly degradable. When exposed to air it oxidizes and its free radical soaking capabilities are muted — it becomes an inert, yet nicely citrus fragranced, cream. This is obvious if you have a vitamin C cream at home; you will see that the cream around the cap turns brown (like an apple slice) indicating that the vitamin C in it has oxidized.
If your are going to purchase a topical vitamin C cream, this is one place where more expensive might be worth the cost. La Roche-Posay makes Active C, a nightly eye cream with 5% vitamin C.
If you are trying to save a few dollars this year, I recommend just eating a citrus fruit everyday. You need only 90 mg of vitamin C daily which can be found in a couple of orange slices. Eating a whole orange or other citrus fruit will easily give you many times the amount of vitamin C you need.
There is no evidence that taking vitamin C supplements or consuming huge amounts of vitamin C will have any impact on your skin. Once you have an adequate supply of vitamin C to make collagen, having a huge oversupply is not likely to lead to more collagen production. But it certainly will lead to lots more vitamin C in your urine — it’s simply eliminated by your kidneys.
Other foods high in vitamin C can be found here.
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