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Vitamin C in Skin Care
By: Peter T. Pugliese, MD
Posted: June 2, 2009, from the June 2009 issue of Skin Inc. magazine.
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GSH is a tripeptide containing three amino acids: glycine, cysteine and glutamic acid. It is a critical antioxidant that acts as an electron donor. GSH reduces any disulfide bond, an –S-S- group, within cytoplasmic proteins to cysteine groups, –S-H. Figure 5 shows this reaction in a simple form illustrating the electron transfer, as well as the structure of GSH. The importance of GSH lies not only in it being a critical antioxidant, but also that it is tied in with the regeneration vitamin C.
Other functions of vitamin C
Ascorbic acid is important in the metabolism of diverse amino acids that lead to the formation of norepinephrine, serotonin, homogenistic acid, carnitine, and hydroxyproline and hydroxylysine. It functions in enzymatic reactions and as a transport for the neurotransmitters, such as norepinephrine and serotonin. In fact, ascorbic acid is both in the production and protection of these neurotransmitters. Carnitine is found in the heart, muscles, liver and skin. One of the major functions of carnitine is to carry long-chained fatty acids into the mitochondria from the cytoplasm of the cell. This accounts for the lack of energy and lassitude seen in patients with scurvy.3
The liver serves as a major detoxifier in the body. Drugs and certain metabolites, such as bilirubin, are toxic if they remain in their original configuration. The liver uses many enzymes to modify these potentially dangerous chemicals, and these reactions often require a reducing agent, such as vitamin C. An example of this action can be found in cigarette smokers who usually have lower vitamin C levels than nonsmokers, even though they have the same vitamin intake.4
Perhaps the single most important function of vitamin C is in electron transport. On the molecular level, life is all about the transfer of electrons because when that process stops, it’s all over.
Finally, vitamin C interacts with mineral nutrients. Did you know that vitamin C intake has nutritional consequences on mineral nutrients, both inhibitory and enhancing type reactions. As an example, vitamin C in the diet can increase the absorption of intestinal iron and selenium, and it reduces the absorption of copper, nickel and manganese. Oddly, it has no effect on zinc, calcium and cobalt, or toxic metals, such as cadmium and mercury.5