hi…
actually, most anti oxidant products are not stable upon exposure to light and oxygen…the same goes for all retinol products for the same reasons…but i came across this research on vit c…it says, in a nutshell, that u gotta rotate ur anto ixidants as research has not proven a single one to be totally effective…and anyways, all research is preliminary…who knows, 40 years down the line they will be feeding us some other shipiel!!!
Vitamin C
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Vitamin C became a celebrated cause in the world of skin after Dr. Sheldon Pinnell from Duke University published a paper in 1992 showing how L-ascorbic acid (a form of vitamin C) reduced UVB damage when applied to the backs of hairless pigs. That was big news and it generated product lines either based on L-ascorbic acid or other forms of vitamin C. Each company said the version of vitamin C they used was best (and most stable) for skin, which created more confusion than helpful information. With the passing years an impressive body of research has evolved proving the benefits, stability requirements, and usage levels for many forms of vitamin C.
Before I get to the benefits vitamin C can bestow on skin, it needs to be stated up front that vitamin C is not the answer to your skin care concerns and it is not the be-all, end-all antioxidant cosmetic companies often purport it to be. There is no conclusive or even vaguely convincing research indicating which antioxidant is best amongst the hundreds and potentially thousands that exist. In fact, there are lots and lots of potent antioxidants, of which vitamin C is just one (Sources: International Journal of Pharmaceutics, July 14, 2005, pages 153-163; Journal of Pharmaceutical Biomedical Analysis, February 2005, pages 287-295; and Journal of Molecular Medicine, August 2000, pages 333-336).
But back to vitamin C. When it comes to applying this vitamin topically at levels ranging from 0.3-10%, the benefits are:
Potent antioxidant, particularly in regard to protecting skin cells from UV-induced damage
Delays tumor formation after (animal) skin is exposed to extensive UV damage
Has a low risk of skin sensitization at concentrations up to 10% in the form of ascorbic acid
Reduces transepidermal water loss, thus strengthening skin’s barrier response
Promotes collagen production and has the potential to thicken the dermis
Reduces inflammation
Ascorbic acid at levels of 5% and above has a positive effect on hyperpigmentation (though the results are not as impressive as hydroquinone, suggesting a combination of the two would be optimal)
Improves the appearance of sun-damaged skin by strengthening skin’s repair mechanisms
Enhances the effectiveness of dermatologist-performed procedures such as peels and microdermabrasion
(Sources for the above statements: International Journal of Toxicology, Volume 24, Supplement 2, 2005, pages 51-111; Experimental Dermatology, September 2005, pages 684-691 and June 2003, pages 237-244; Dermatologic Surgery, July 2005, pages 814-817; Nutrition Reviews, March 2005, pages 81-90; Skin Pharmacology and Physiology, November-December 2004, pages 298-303; BMC Dermatology, September 2004, page 13; International Journal of Dermatology, August 2004, pages 604-607; and Archives of Facial Plastic Surgery, Volume 5, Issue 2m March-April 2003, pages 145-149.)
An article in Plastic and Reconstructive Surgery (January 2000, pages 464–465) nicely summed up the positive effects of vitamin C stating that it “…is a valuable antioxidant and protectant against photodamage that is created by sunlight in both the UVB and UVA bands… . Although oral supplementation may also be useful, topical preparations are able to deliver a higher dosage to the needed area. Topical vitamin C…augments the skin’s ability to neutralize reactive oxygen singlets [free-radical damage] that are created by the ultraviolet radiation, thereby preventing photodamage to the skin…Used appropriately, topical vitamin C is an important adjunct to the use of sunscreens, an adjunctive treatment to lessen erythema [redness] in skin resurfacing, a helpful adjunct or an alternative to Retin-A in the treatment of fine wrinkles, and a stimulant to wound healing.”
As with most vitamins, there are many forms of vitamin C but the ones primarily found in skin-care products are ascorbic acid, L-ascorbic acid, tetrahexyldecyl ascorbate, ascorbyl palmitate, ascorbyl phosphate, ascorbyl glucoside, retinyl ascorbate, ascorbyl stearate, sodium ascorbyl phosphate, and magnesium ascorbyl phosphate (Source: International Cosmetic and Ingredient Dictionary and Handbook, 10th Edition, 2004). So is there a best form of vitamin C for your skin? The simple answer is no, though many seem to be reliable and beneficial for skin.
L-ascorbic acid is a good option in terms of its potential bioavailability on skin, but Pinnell’s own research about his prized form of vitamin C shows it is highly sensitive to formulary concerns, including concentration and the pH needed for it to remain stable (Source: Dermatologic Surgery, February 2001, pages 137–142). Current research has demonstrated that adding magnesium sulfate with L-ascorbic acid can make this form of vitamin C stable much longer without acidic pH concerns (Source: Journal of Cosmetic Science, January-February 2004, pages 1-12).
Ascorbyl palmitate is considered stable and there is research showing it to be effective as an antioxidant (Sources: Photochemistry and Photobiology, June 1998, pages 669–675; and Journal of Pharmaceutical and Biomedical Analysis, March 1997, pages 795–801).
In terms of stability, magnesium ascorbyl phosphate is reliable for skin as well (Source: Journal of Pharmaceutical and Biomedical Analysis, Volume 15, Issue 6, March 1997, pages 795-801). A single study demonstrated that it can also be effective for skin lightening when used at a 10% concentration (Source: Journal of the American Academy of Dermatology, January 1996, pages 29–33). That’s good to know, but, to the best of my knowledge, there are no products with that amount of magnesium ascorbyl phosphate available and no other research has duplicated those results (or compared it to other effective antioxidants).
Ascorbic acid (Sources: Skin Pharmacology and Physiology, July-August 2004, pages 200-206 and Experimental Dermatology, June 2003, pages 237-244) and retinyl ascorbate (Source: Free Radical Research, May 2005, pages 491-498) have also been shown to be potent and effective forms of vitamin C (with ascorbic acid being the entire vitamin C molecule). Rounding out the list is sodium ascorbyl phosphate. Research has shown it to be a stable form of vitamin C (Source: International Journal of Pharmaceutics, April 30, 2003, pages 65-73).
IMPORTANT NOTE: All forms of antioxidants are extremely vulnerable to the presence of light and oxygen. When antioxidants are exposed to sunlight or air they quickly break down and deteriorate, losing their benefit for skin. This means the type of packaging used for formulations containing antioxidants (as well as other types of ingredients) is critical. As a general rule it is best to completely avoid products packaged in jar containers or any other container that exposes the product to air or light.
REMINDER: Despite the benefits topical vitamin C provides, it is important not to get hung up on any one antioxidant, regardless of its history. Aging is more complicated than just the loss or need for vitamin C—or any other vitamin, enzyme, protein, peptide, fatty acid, amino acid, or lipid in the skin. Although vitamin C is clearly an effective ingredient for skin, there are many antioxidants that are as good, including beta-glucan, vitamin E, vitamin A, green tea, grape extract, selenium, curcumin, lycopene, superoxide dismutase, and on and on. Furthermore, many researchers studying antioxidants and their effects on the human body feel the best plan of attack is to use multiple antioxidants rather than narrowing your choices to a few well-publicized options or the mistaken belief that there is a single “best” antioxidant to apply and consume (Sources: Archives of Dermatologic Research, April 2005, pages 473-481; Plastic and Reconstructive Surgery, February 2005, pages 515-528; Photochemistry and Photobiology, January-February 2005, pages 38-45; and Mutation Research, April 2005, pages 153-173).
Vitamin C: Real Benefits of Topical Treatment Cosmetics Cop: Skin Care & Makeup Tips & Reviews : Cosmetics Cop: Skin Care & Makeup Tips & Reviews